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View Full Version : Bathtub installation -- order of installation (end pony wall, tub, heated floor)?



jch
07-10-2011, 01:00 PM
Here is my gutted bathroom. I have a left-hand-drain Kohler Villager cast iron tub (with apron) that I want to install along the far wall (i.e. along the wall that has exposed insulation):

13500

The tub is 60" long and the available space is 78" (with a downward-sloping ceiling).

Questions:
1) Do I install the tub (on a ledger board) *before* building a pony wall along the non-drain end of the tub? Or do I build the short (20" 2x6) pony wall first?

2) I plan on installing a heated tile floor. Because the room has some funny angles (not visible in the picture), I was going to run my own heating cables and then pour Self-Leveling Cement. Do I run the cables and pour the whole floor *before* installing the tub? Or do I put in the tub first and then pour SLC on the remaining area? (The heating cable would only be under the exposed tiles, not the tub). My concern is the joint between the tub & SLC, and the reduction of tub-height -- it's only 14" to start with.

This is my first bathroom reno, so I'd appreciate any tips.

Thanks!
.../j

Terry
07-10-2011, 01:08 PM
In this case you could do it either way, either set the tub first or install the pony wall first.

When we install a tub, we put a 2x4 flat; if that is the right height of the concrete pour, and then pour up to that. I don't like setting a heavy tub on concrete if it's that thin. The 2x4 makes a nice resting place for the apron.

Then you can finish tile up to the tub.

http://www.terrylove.com/forums/showthread.php?33212-Installing-a-Kohler-Villager-Cast-Iron-Tub

jch
07-10-2011, 01:20 PM
Thanks for the speedy reply Terry!

I'm hoping that the concrete won't need to be that thick (for headroom). I was hoping for more like 1/4 - 3/8" thick SLC if possible. Or am I dreaming?

And does the wooden apron support stick out in front of the apron? Or do you try to install it flush with the front of the apron?

Thanks!

Terry
07-10-2011, 01:39 PM
I haven't installed the electric heating mats, but they may go under the tile without doing too much.
If that is the case, just set the tub on the plywood.

You only support at the back wall. One stringer does it.

jch
07-10-2011, 01:49 PM
The more I think about it, the more I think that I'd better do the SLC last. I *know* I'd end up dropping something on it while wrestling a cast iron tub around the room... :)

So how does this sound then:
1) Build 2x6 pony wall along non-drain end of tub
2) Install wooden 1x4(?) along floor where tub apron will sit
3) Install 1x4 or 2x4 ledger along wall (depending on clearance of tub), measuring up from top edge of apron support
4) Skid/rotate tub into place using instructions here: http://www.terrylove.com/forums/showthread.php?33212-Installing-a-Kohler-Villager-Cast-Iron-Tub
5) Install in-floor heating cable
6) Pour SLC to bury cable
7) Install Schluter Ditra anti-fracture membrane on top of SLC with thinset
8) Install floor tiles

Sound good??

Terry
07-10-2011, 01:54 PM
You have enough room there that you may be able to just slide the tub in.

But either way, so far, so good. That looks close enough for a plan.

jch
07-10-2011, 01:56 PM
Excellent. Thanks!

jadnashua
07-10-2011, 02:56 PM
SLC is MUCH easier to get nice and level (with no waves, etc.) if you make it a little thicker than you plan. Also, over a wooden subfloor, you need lath - I'd suggest a plastic lath rather than metal as the metal can mess with the insulation on your heating wires if you step on them before the pour. Depending on the slc chosen, some require 1/2" above the highest point when used over wood...take the longest level you have to determine how level the floor is before calculating how much slc you need. the worst thing is to have too little. Check out www.johnbridge.com (http://www.johnbridge.com) and read up on slc use - lots of threads and info in their 'Liberry'. Finally, ensure you get a good coat of the primer for the slc or the whole install will be at risk.

jch
07-10-2011, 03:10 PM
Thanks for the tip. I haven't checked out johnbridge lately, so I'll drop by there to refresh my memory.

The floor is currently within 1/8" of being flat and level. I pulled up the subfloor and planed down the top of the joists in line with a laser.

The only reason for me using SLC is to bury the heating wire. Perhaps it'd be worth spending the extra for heating mats and using thinset instead??

jadnashua
07-10-2011, 05:17 PM
Either will work, but slc over top does make it nice and flat while embedding the heating elements well, optimizing the heat transfer and providing a nice flat surface to tile on.

johnfrwhipple
07-11-2011, 05:50 AM
There are many heating mats that can be used for sure but I'm more of a fan of heating cables.

The Mats offer up a little extra speed in installation but a cable system offers a direct bond from the top of the levelling compound to the subfloor and does not rely on the manufacture's seaming process of the two sheets. With a mat system you need to work the thin-set into the fleece very well and this can be hard to do well without over watering the thin-set and weakening that product.

Once the cable heat is installed you might consider a product like Schluter's 'Ditra', Nobel Company's 'Nobel TS' or Mapei's 'Crack and Sound Membrane' over your levelling pour. Remember if you use the Ditra product you will strictly reduce the amount of setting materials available to you. Here in Vancouver the crews I'm working with have been using lots of the Mapei product and many of the setters online have been using Nobel TS. Mostly because they can use the same thin-set to set above and below the membrane.

If this is your first bathroom renovation you might further consider using a liquid membrane for all these steps including the bathtubs walls. Look at products from Mapei (AquaDefense) and Laticrete (Hydro Ban). Both offer up crack surpression and waterproofing. Much easier to work with than Kerdi.

Good Luck.

hj
07-11-2011, 06:25 AM
Installing the bathtub will be MUCH easier if it is done BEFORE the pony wall is constructed.

jch
07-11-2011, 10:58 AM
There are many heating mats that can be used for sure but I'm more of a fan of heating cables.
I'm looking at using the NuHeat Solo/220 wall controller (because it seems easy to program without digging out a manual each time). Is there a type of compatible heating cable you'd recommend? I was thinking of using TrueComfort because of the floor attachments and easy availability...


Once the cable heat is installed you might consider a product like Schluter's 'Ditra', Nobel Company's 'Nobel TS' or Mapei's 'Crack and Sound Membrane' over your levelling pour. Remember if you use the Ditra product you will strictly reduce the amount of setting materials available to you. Here in Vancouver the crews I'm working with have been using lots of the Mapei product and many of the setters online have been using Nobel TS. Mostly because they can use the same thin-set to set above and below the membrane.
The original plan was to lay down:
3/4" ply with no underlay
SLC primer
Heating cables
SLC primer
SLC
Ditra
Porcelain Tiles

Do I need underlayment if I use the SLC primer directly on the plywood? Or would underlayment mean that I could do without the plastic lathe in the SLC??


If this is your first bathroom renovation you might further consider using a liquid membrane for all these steps including the bathtubs walls. Look at products from Mapei (AquaDefense) and Laticrete (Hydro Ban). Both offer up crack surpression and waterproofing. Much easier to work with than Kerdi.
Interesting. My neighbour's son (a tile setter for 25+ years) swears by RedGuard. Maybe it's the heavy Mike Holmes/Schluter PR, but I'm having a hard time trusting that a rubbery paint-on membrane won't dry out/crack over the years... (Actually, that I'd be able to install it so that it wouldn't crack..)

I've already bought a Schluter shower kit (pan, curb, drain, Kerdi) to use in the *other* bathroom reno in the house so I'm gonna have to learn how to use it/curse it at some point :-) I'll definitely consider using a paint-on membrane on the first one.

Thanks!

jch
07-11-2011, 11:00 AM
Installing the bathtub will be MUCH easier if it is done BEFORE the pony wall is constructed.
Would you recommend connecting the drains before building the pony wall? I have access from the bathroom underneath (it's all bare joists baby!).

jadnashua
07-11-2011, 12:27 PM
It's always easiest to install the drains when you have easy access. It can be done either way, but afterwards requires more skill.

Ditra has a minimum tile size (2"). This is to ensure that enough of the tile is supported by pillars of thinset around the waffles so it won't cock if stepped on with a high load point source. Other than that, it's pretty easy to use. Some thinset manufacturers sell a decent unmodified and you can mix it either with water (and maintain the unmodified characteristics), or mix it with their addative, and that makes it a modified thinset (rather than buying a modified at the plant that you then mix only with water). Done this way, you don't need two different thinsets, just depends on how you mix it up. Because of the waffles in Ditra, the amount of actual thinset used may end up less than with a plain membrane - painted on or embedded.

The critical thing with Kerdi is mixing the thinset properly and using a quality product. Second, getting it up before the thinset skins over. embedding is really pretty easy once you get the hang of it if the thinset is done right. If you can find it, DitraSet is a really nice, creamy thinset made for Schluter. The key to proper thinset mixing is the right mix, the right paddle, and mixing it long enough. Using a timer helps. most people don't mix their thinset per the manufacturer's instructions. The difference in texture can be quite dramatic - those extra minute(s) really make a difference. Some people compensate by adding extra water. this is often unnecessary, and weakens the thinset, if the proper mixing is done.

A manufacturer's rep told this story to us in a class. they had a pro complain about the texture of one of their thinsets. The pro watched as the guy mixed up a batch. Knowing it would be hard to change the guy's mind, they said let us research it. They came back a few weeks later and told him they had some new stuff for him to try. The guy mixed it up the way he usually did, and the tech said...keep mixing. this went on for a couple of iterations. Then, after the manufacturer's mixing time had been used, he told the guy that's good. The guy then commented that the stuff was MUCH better. Then, the rep told him that it was exactly the same thinset...just that it had been mixed per instructions.

The gotcha with paint on membranes is achieving the required thickness. Most people have a difficult time actually getting it thick enough, and pinholes are a potential problem as well. Get it too thick and you've spent a bunch more in materials and time than needed. Too thin, and it won't do the proper job.

jch
07-11-2011, 12:50 PM
Ditra has a minimum tile size (2"). This is to ensure that enough of the tile is supported by pillars of thinset around the waffles so it won't cock if stepped on with a high load point source. Other than that, it's pretty easy to use.

Roger! I'm planning on using 12" x 24" Porcelain tiles, so the bigger problem will be floor flatness... Not sure whether my thinset workmanship will be good enough to get these tiles in-plane with each other....

Any ideas about the questions raised in post #13 (above)?? (Heating wire compatibility, underlayment requirements, lathe requirements)

jadnashua
07-11-2011, 01:39 PM
All of the slc installation instructions I've read (and there are some new ones out there I've not read up on) require lath on a wooden subfloor. Ardex has a new one that might not. On large format tile, you may want to look into something like the Tuscan Leveling System or the QEP system (cheaper, since you don't have to buy a special tool and available, here at least, in HD). These utilize a t-shaped strap and a break off bracket to hold the tile in plane while the thinset cures, then you break them off (they break off below the tile) and then grout. On any large format tile like that, you want to burn a thin coating of thinset on the backs prior to setting them (use the flat side of the trowel and really push the thinset into the tile). Done right, the thinset gets pushed into the small pores of the tile, and radically inmproves the bond strength. If you don't push it in enough, the thinset can just roll around on the back of a good porcelain. Flat is critical when using large format tile...even a pro gets slowed down when the prep work is marginal on a wavy floor.

jch
07-13-2011, 03:04 PM
Thanks! Given that large-format tiles are so demanding in terms of flatness, perhaps I should defer buying the tiles until I see how flat of a pour I can do myself.... I could get lucky.

There's a pro tile supply place in town here. I'll go down and read the instructions/requirements on some SLC bags there so I won't have to keep pestering you fine folk with newbie questions. :-)

Obama the Plumber
07-13-2011, 04:40 PM
Make sure when you install the tub drain, that you don't put anything on the threads of the lower drain fitting. That works by clamping the metal threaded drain with the lower shoe, and sandwiching the tub and rubber washer in between.

You can put putty under the flange, that is between the tub and metal drain.
Below the tub, is the rubber washer and then right below that the shoe which receives the threaded drain from above.

The drain would seal even without the putty if it's threaded up snug and tight.

The other day I say someone put Teflon tape on the threads, and it prevented the drain from threading down completely and "clamping" the tub. I had to remove everything, pull off the tape, clean things up and then thread it down until it clamped. Even when I explained why I was doing it that way, the response I got was, "It should have worked"
No, It in fact does not work! He had so much tape on the threads that there was a gap below the tub of over a 1/4". The drain had bottomed out with all the tape and it was stuck before it could clamp the rubber washer against the bottom of the tub. Needless to say, there was plenty of water dribbling downstairs before it was fixed.

Here's a big clue guys. Teflon tape can only be used on tapered threads.
That would be places like shower arms
Nipples that thread into a female IP fitting.

Places you can't use tape:
compression fittings
Flex connectors, (they have rubber seals on the ends)
Flexible lav supplies (they have seals on the ends)

So.....get it right, or I will make it right for you.

http://www.terrylove.com/images/tub_drain_washer_silicone.jpg

All this gooey Silcone dripped everywhere and it was a horrible leak.

jch
01-06-2012, 01:35 PM
How do you folks recommend getting a SLC install flat enough to install 12x24" tiles??

I was considering putting a skinny (1" wide?) 1/2" thick plywood strip around the outside of the room to rest a screed on. Remember, I'm going to install heating wires and plastic lath first.

Would the 1/2" plywood strip help me make the SLC more level? Would it interfere with the expansion/contraction of the SLC when the heat is on?

Suggestions?? Thanks!

jch
06-18-2012, 10:35 AM
There are many heating mats that can be used for sure but I'm more of a fan of heating cables.

It took me a long time to get the rest of the room ready, but I finally installed NuHeat heating cables this week and passed my electrical inspection. Really nice system to work with.

Then this weekend I rolled on Mapei Primer T onto the exterior-grade plywood subfloor (goes on pink, but dries clear -- very cool); stapled down Mapelath plastic lath; then poured 1/2" of Mapei Novoplan Easy SLC.

Thank you all for your recommendations so far--beautiful results. Floor is now true and level -- less than 1mm (1/25") gap when checking with a 4 foot level.


Which brings me to the question about the next step... the decoupling/anti-fracture layer (as specified by the TCNA's handbook):


Once the cable heat is installed you might consider a product like Schluter's 'Ditra', Nobel Company's 'Nobel TS' or Mapei's 'Crack and Sound Membrane' over your levelling pour. Remember if you use the Ditra product you will strictly reduce the amount of setting materials available to you. Here in Vancouver the crews I'm working with have been using lots of the Mapei product and many of the setters online have been using Nobel TS. Mostly because they can use the same thin-set to set above and below the membrane.

I've been so pleased with the Mapei products I've used so far (Primer T, Mapelath, and Novoplan Easy) that I'd like to try staying with them for the decoupling layer. Called their Tech Services hotline but they said they don't sell anything similar to Schluter's Ditra.

Looked on Mapei's website for 'Crack and Sound Membrane' but found quite a few products that have that in their description:
- Mapeguard 2 sheet membrane,
- Mapelastic 315,
- Mapelastic AquaDefense,
- Mapelastic CL, and
- Mapelastic HPG.

**Are any of these the product you're suggesting??



If this is your first bathroom renovation you might further consider using a liquid membrane for all these steps including the bathtubs walls. Look at products from Mapei (AquaDefense) and Laticrete (Hydro Ban). Both offer up crack surpression and waterproofing. Much easier to work with than Kerdi.

I've bought Mapei AquaDefense for the shower walls but haven't installed it yet -- thanks!

johnfrwhipple
06-19-2012, 07:55 AM
It took me a long time to get the rest of the room ready, but I finally installed NuHeat heating cables this week and passed my electrical inspection. Really nice system to work with.

Then this weekend I rolled on Mapei Primer T onto the exterior-grade plywood subfloor (goes on pink, but dries clear -- very cool); stapled down Mapelath plastic lath; then poured 1/2" of Mapei Novoplan Easy SLC.

Thank you all for your recommendations so far--beautiful results. Floor is now true and level -- less than 1mm (1/25") gap when checking with a 4 foot level.


Which brings me to the question about the next step... the decoupling/anti-fracture layer (as specified by the TCNA's handbook):



I've been so pleased with the Mapei products I've used so far (Primer T, Mapelath, and Novoplan Easy) that I'd like to try staying with them for the decoupling layer. Called their Tech Services hotline but they said they don't sell anything similar to Schluter's Ditra.

Looked on Mapei's website for 'Crack and Sound Membrane' but found quite a few products that have that in their description:
- Mapeguard 2 sheet membrane,
- Mapelastic 315,
- Mapelastic AquaDefense,
- Mapelastic CL, and
- Mapelastic HPG.

**Are any of these the product you're suggesting??




I've bought Mapei AquaDefense for the shower walls but haven't installed it yet -- thanks!

Mapelastic HPG - nope
Mapelastic CL - ? never used it can't say
Mapelastic Aquadefence, I'd rather use a sheet membrane over fresh self leveler
Mapelastic 315 - might be an option but this stuff is hard to work with
Mapeguard Crack and Sound is the way to go. I see many tile pros using this over the self lever coat. You will need to take care priming again and rolling out the product. If your not in a rush let that self lever cure a good week. There is little forgiveness in install this membrane so if you go side ways it's better to abort and add in a seam. I have seen loads of it installed but never once installed it myself. You need a 100 pound roller as well to install this sound and crack membrane.

A lot of tile men are switching to Noble Seal TS for this type of application. In either install you will have overlapping of sheet seams. Installing a sheet membrane over such a large space is no hard but should be done with a helper. We did my deck in Noble Deck and troweled on the thinset and rolled on the Noble Deck in one go keeping the thin set fresh and routinely checking the coverage rates.

As for the Aquadefence on the bathroom walls you will love this! How many square feet of wall and shampoo niche space do you have? How much Aqua Defence did you buy? Do you have a plan for the tile flange on your tub? Ideally your backer board laps this but most times the board is installed above it? Have you seen the detail we use for these type of installs? Did you get any of the fleece reinforcing mesh? What type of backer board are you going to use?

JW

jch
06-19-2012, 11:14 AM
Thanks -- I just called Mapei's Technical Services again to double-check on cure times/compatibility etc. They echoed your advice:

Mapelastic CI is the cheaper version of AquaDefence. Offers Crack Isolation, but not waterproofing. AquaDefence provides both. They said AquaDefence would be the easiest product for me to put on the floor (2 coats rolled-on).

** I'm unsure whether to use reinforcing fabric on the floor. Reminder: I'm using 12" x 24" porcelain floor tile.

Mapelastic 315 is trowelled-on and was not recommended for a DYI'er like me. They said it's usually used over cracked concrete floors.

Mapeiguard 2 sheet membrane was their top pick for crack isolation, but said it was harder to install than a roll-on.

Mapelastic HPG is their older version and has been replaced by the newer types (above).



As for the Aquadefence on the bathroom walls you will love this! How many square feet of wall and shampoo niche space do you have? How much Aqua Defence did you buy? Do you have a plan for the tile flange on your tub? Ideally your backer board laps this but most times the board is installed above it? Have you seen the detail we use for these type of installs? Did you get any of the fleece reinforcing mesh? What type of backer board are you going to use?

I've already installed HardieBacker 500 over top of vapour barrier plastic in the tub area. The HardieBacker overlaps the cast iron tub's flange (shimmed it out) and stops about 3/16" off the tub deck. The vapour barrier is hanging out below the HardieBacker into the tub for now. I was going to roll-on AquaDefence down the walls and along the underside of the HardieBacker edge, then trim the plastic flush, and fill with silicone caulking.

I have 1 gallon of AquaDefence to cover the tub surround area and slanted ceiling. It's about 69 sq ft of surface area (walls and ceiling) so it'll be close. I don't have any reinforcing mesh for the corners yet. Still debating whether it'll be necessary (or make the wall too uneven in the corners) since I'll first used fibreglass mesh and thinset in the corners and on the HardieBacker seams.

Advice?

jch
06-19-2012, 04:36 PM
i just checked on buying some Mapei Mapeguard 2 anti-fracture membrane. Turns out the places in town here only sell it by the entire roll -- enough for 225 sq ft -- overkill for my 40 sq ft bathroom...

They sell Schluter Ditra by the foot, but then there's the whole issue of using unmodified thinset to set my 12x24" tiles -- not good.

Haven't been able to find anyone local who sells Noble TS yet :-(

Which leaves me (for now) with Mapelastic AquaDefence to use on the SLC floor. Since I originally posted, random hairline cracks have appeared on the SLC (now 3 days since pouring). The cracks are random and do not seem to coincide with any seams/joints/joists so I'm assuming that it's just a result of it drying... (?)

Do I need to use any reinforcing fabric when I put AquaDefence down on the SLC floor?? This recent appearance of fine cracks has me nervous...

jadnashua
06-19-2012, 05:59 PM
A good unmodified (dryset) thinset will have in the order of 250-300#/sq in of bond strength to porcelain...how much do you really need? On a 12x24" tile at the lower end, that's 36 TONS to break it off. The Ditra and the floor and the house will fail long before that happens. Also, think about this: a good porcelain has an absorbtion rate of less than 1%, the waterproofing material (be it Ditra or some other membrane) is less than that. Where will the moisture go that needs to evaporate so the modified mortar can properly cure? A good dryset doesn't need to dry, only cure, and it will do that without any help inside of a plastic bag, let alone between two impervious surfaces.

If you really must have a modified, and want to use Ditra, if you call, they'll likely tell you you can IF you use a rapid set...not something a DIY'er should really consider, though. Laying large format tile is tough to get them perfectly lush and level - even the slightest inconsistency will result in a corner being low or high - the size amplifies any small error into a huge one with that size tile. You may want to consider something like the TLS or LASH leveling system.

Both porcelain and glass tile have been used for centuries...long before modified thinsets became available. Yes, a modified is stickier, probably has a longer pot life, and may be stronger, but there are tiled floors that are centuries old that have stood the tests of time without it.

johnfrwhipple
06-20-2012, 06:36 AM
You got me in a pickle.

I think it's best to put the brakes on the job and see what the self lever does. If it continues to crack badly and you end up with de-bonding it could be a "Do Over".

For starters I would not depend on the Aqua Defence as a crack isolation membrane without the fleece. I would not install the Aqua Defence over the self lever until that has fully cured which could be in a couple weeks. I would in a heart beat use Ditra over this and have done this type of application for years with not a single call back. The procedure to install the 12"x24" tile over your Ditra would be like this;

1). Pre-Fill waffles with non-modified thin-set (let dry overnight at least)
2). Scratch on non-modified thinset in a small area (say 1'x4') (1/4" x1/4" square notch trowel)
3). Drop on a small layer of mortar mix (perhaps a 1/4" of material)
4). Scratch on Non-modified thinset to the tile (1/4" x1/4" square notch trowel)
5). Drop over mortar mix and beat in with rubber mallet
6). Repeat

Here is a look at some 1'x2' Travertine that my setter installed for me. There is Ditra under that tile.

http://i839.photobucket.com/albums/zz314/jfrwhipple/Vancouver%20curbless%20showers/VancouverCurblessShower.jpg

http://i839.photobucket.com/albums/zz314/jfrwhipple/Tiling%20over%20Ditra/IMG_1629.jpg

http://i839.photobucket.com/albums/zz314/jfrwhipple/Tiling%20over%20Ditra/IMG_1630.jpg

Here you can see my setter using a White Non-Modifed Thinset and the Mortar Mix. Learning how to fluff the mortar mix and how much to use takes a little practice but after setting 3-4 tiles you will be on a roll. The mortar mix supports the tile while the thinset cures. Do not be afraid to beat the tile into position - you are after 80-95% coverage for a solid install.



I would use this approach over any levelling clip. Schluter Systems prefers the use of Ardex setting materials with their products and if you use Ardex with Ditra you can get a ten year warranty. I have been told in the past Grani Rapid is fine but to not use the liquid. This makes no sense to me since Mapei says you have to use the liquid to mix grani Rapid. Ardex is available here in Vancouver if you want to cover all your basis.

Noble Seal TS would be a great option and allows for modified thinsets and is a true crack isolation membrane - If you need only 40 square I could sell you that off my roll or you can order direct from Noble Company. I'm placing a new order next week, if your not in a rush you can piggy back on my order. Remeber Ditra is not a crack isolation membrane and will not help you there. What it does do is cover up all those little hairline cracks with one big orange band aid and lays down easier than installing a sheet membrane.

Tough call. The safest play at this time is to wait. Finish the tub surround and play it by ear at this point. Can you send some pictures of the floor?

JW

jch
06-20-2012, 01:15 PM
Wow.

Here's what the floor layout looked like before the pour:
16611

This area has hairline cracks that don't seem to align with joists nor with wires or any other discernible structure:
16612

Here's a close-up of some hairline cracks that have formed near the toilet drain:
16613

This Novoplan Easy SLC pour was done 3-1/2 days ago. The SLC is 1/2" thick on: exterior 3/4" plywood, 2x10 joists on 16" centers, 8 foot spans (better than 1/800 rating); primed first with Mapei Primer T; mapelath stapled every 2-4".

Do these cracks looks severe enough to worry about (at this point)?? Knocking on the floor it sounds solid.

jadnashua
06-20-2012, 04:25 PM
Can't tell for sure, but did you use some foam around the obstructions and wall? You can't pour it directly against unyielding structures - it needs to be able to expand and contract. Same idea as not grouting tile tight against a wall or other solid thing.

jch
06-20-2012, 05:08 PM
Yup, 1/2" foam around the entire perimeter of the pour, plus 3 wraps of foam sill-gasket around the toilet waste pipe.

chefwong
06-21-2012, 05:17 AM
JW -

Interesting read on the combo you use....unmod and then mortar mix and then a good 'ole fashion hammer I suppose. Back when I did not know all the TCNA rules.....I leveled a room with Lati. 254 as thick as 2" .....just using thinset and a rubber mallet. It has had cordless batteries drop 7 feet high at least 4 times, etc - and the floor and tile are still intact !

johnfrwhipple
06-21-2012, 06:53 AM
JW -

Interesting read on the combo you use....unmod and then mortar mix and then a good 'ole fashion hammer I suppose. Back when I did not know all the TCNA rules.....I leveled a room with Lati. 254 as thick as 2" .....just using thinset and a rubber mallet. It has had cordless batteries drop 7 feet high at least 4 times, etc - and the floor and tile are still intact !

I like to punch the tiles with my fist, hit them with the palm of my hand or use the rubber mallet what ever beats them into the mortar mix and yields me solid coverage.

JW

johnfrwhipple
06-21-2012, 06:59 AM
Wow.

Here's what the floor layout looked like before the pour:
16611

This area has hairline cracks that don't seem to align with joists nor with wires or any other discernible structure:
16612

Here's a close-up of some hairline cracks that have formed near the toilet drain:
16613

This Novoplan Easy SLC pour was done 3-1/2 days ago. The SLC is 1/2" thick on: exterior 3/4" plywood, 2x10 joists on 16" centers, 8 foot spans (better than 1/800 rating); primed first with Mapei Primer T; mapelath stapled every 2-4".

Do these cracks looks severe enough to worry about (at this point)?? Knocking on the floor it sounds solid.

I have not seen the Mapelath go in at the same time as the self levelling stage before. Whose idea was this? Did Mapei recommend it? Is the Mapeilath installed the right way up?

If your self lever has been installed for a few days and sounds "solid" when tapped you should be OK. Perhaps call Mapei - one of their new reps lives in Victoria and was a setter for years, I'm blanking on his name.

Some times when you get cracks like this it is a sign of over watering the self leveller.

You might wait another four days and try one of my rules for tiling. "Never tile anything you can't hit with a hammer". If you give a few well placed blows to the floor (in between heating wires) and you don't blow away your prep or your prep work doesn't crumble it should be OK.

JW

jch
06-21-2012, 10:42 AM
I have not seen the Mapelath go in at the same time as the self levelling stage before. Whose idea was this? Did Mapei recommend it? Is the Mapeilath installed the right way up?
I tried to follow the TCNA 2011 Handbook and Mapei's Technical Data Sheet as closely as possible.

TCNA specifies the following when installing Interior Floors with Radiant Heat over Wood (RH140-11, p. 103):
16621

Mapei's Technical Data Sheets also recommend installing Mapelath before pouring Novoplan Easy:
http://www.mapei.com/public/CA/products/NovoplanEasy_TDS_EA.pdf
"When applying MAPEI underlayments to plywood flooring, mechanically fasten MapelathTM or diamond mesh on top of the primed surface (meeting the requirements of ASTM C847) before application of Novoplan Easy. Refer to the current Mapelath TDS for installation instructions."

The Mapelath TDS says:
http://www.mapei.com/public/CA/products/Mapelath_TDS_EA.pdf
"1. Install Mapelath over the primed plywood or OSB. The lath should have a 2" (5 cm) overlap at all seams, stapled flat and uniformly.
2. Apply a MAPEI self-leveling underlayment at a minimum thickness of 3/8" (10 mm), completely encapsulating the Mapelath. Reference the TDS for the leveler to be used and for in-depth application instructions."

and "Lay out Mapelath over the substrate ridge-side down. Cut to fit." which is what I did.



If your self lever has been installed for a few days and sounds "solid" when tapped you should be OK. Perhaps call Mapei - one of their new reps lives in Victoria and was a setter for years, I'm blanking on his name.

Some times when you get cracks like this it is a sign of over watering the self leveller.
Novoplan Easy's TDS says:
"Into a clean mixing container, pour the required amount of cool, clean potable water. If available water is not cool, chill water to 70F (21C). Add Novoplan Easy powder while slowly stirring. Mix water and Novoplan Easy powder to a mixing ratio of 5 to 5.28 U.S. qts. (4,73 to 5,0 L) water per 50-lb. (22,7-kg) bag of Novoplan Easy. The mixing ratio must remain consistent. Do not overwater material."

I measured 5L of cool water into each bucket (with a measuring cup!) and used a timer to make sure I didn't mix it beyond 2 minutes so should be in the right range. It was a cool rainy day though (about 60% humidity) so that may have been enough to push the water content over the edge.

I called Mapei again and they said it should be pretty much done shrinking by now (4 days) and that the cracks (too small to fit a piece of paper into) should be fine if the floor feels solid (which it does), but I should put an anti-fracture membrane down (as you folks have recommended).

It's just a matter now of choosing which one.

jadnashua
06-21-2012, 02:18 PM
The lath is there to strengthen the slc...so, it must get installed before pouring. WIth a 'normal' concrete slab, you want your reinforcement in the middle, but that isn't what's called for with slc where it should end up with intimate contact because of the viscosity of the material, fully encasing it.

johnfrwhipple
06-22-2012, 07:46 AM
Well this is a good thread.

If you have the lath installed and it's solid you would think that it is going to add a ton of strength to this subfloor. But the fact we have hairline cracks is cause for perhaps another step.

I'm thinking you should just go with the Ditra or wait for my next Noble order to arrive. I'm ordering another roll of Noble Seal TS and a part roll of Noble Seal SIS for a sound proofing job I'm working on.

If you want a part roll of the Mapei Sound and Crack I'm sure my friend Kip can sell you some - he uses it all the time.

I have to say John you are doing a great job of showing up most pros with your attention to detail - nice work. Thanks for sharing!

JW

jch
06-22-2012, 09:10 AM
Mapei said that the hairline cracks are probably not all the way through the pour--just on the surface. There is definitely no visible change in crack width when I bounce my full body weight near them. My guess is that the hairline cracks are from having slightly too much water in the mix--I used the upper end of the prescribed range but it was a super humid day. The cracks didn't appear until day 3--long after most pros would've started tiling.

That said, I agree that a crack-isolation layer would be wise. Ditra is available locally by the foot so I think I'll go with that.

Question: Which specific thinset should I use to attach the Ditra to the SLC? Over wood I know I would use a modified thinset, but over SLC I'm not so sure. Locally I can get Mapei and Ardex products. Just not sure which specific version is appropriate.

Thanks again for your help.

jadnashua
06-22-2012, 02:02 PM
If you don't have it, download the Ditra handbook from the www.schluter.com (http://www.schluter.com) website. It gives you all you need to know about installing it over all acceptable substrates. It's a good reference to have.

From page 9:
Setting and Grouting Materials
Unmodified thin-set mortar – ANSI A118.1

You want a premium quality dryset mortar, not the ecomony price leader in the line.

johnfrwhipple
06-24-2012, 09:21 AM
You have gone this far with the Mapei line of materials. Why not use their Kerabond (http://www.mapei.com/public/CA/products/Kerabondkeralastic_TDS_EA.pdf) setting material. If you buy some Keralastic you can mix up some modified thin set for your tile install over the Aqua Defence.

http://www.mapei.com/public/CA/products/Kerabondkeralastic_TDS_EA.pdf

Using a plain non-modifed thin-set it is important to note that they take a longer time to get a good bite. Do not set the Ditra and then tile the same day. Any checking of coverage will cause a suction effect on the Ditra and could cause a bond failure as the Ditra is pulled off the self leveller.

Better be safe and set the Ditra and then let it cure out a good couple days. I've layed a lot of Ditra with modified setting material and do so at my own risk, knowing that Schluter does not allow or warranty this work without written permission from head office. If your in a hurry and I don't think you are then finsih the floor with Ardex setting materials from setting the tile to grouting - this will allow you to use premium modifed thin sets and even double your warranty if you use the right products.

Kerabond is a great non-modifed thinset. I spoke with a top tech at Schluter some time back and he suggested using 'White' non-modifed thinset. I can not remember the entire conversation but I believe that white thinset is a better quality than grey when comparing apples to apples. I have followed this advice and when working with non-modifed thinsets prefer the white for my bonding applications.

Kerabond is sold in white and gray. Next time I see my rep I'll ask him if he knows if one is stronger or better than the other.

Good luck.

JW

jadnashua
06-24-2012, 02:09 PM
In a class I went to, they said that the reason white thinset was more expensive (often a buck or two a bag) is that to get it white, they have to use cleaner, higher quality sand and components. Now, I don't know if it is actually stronger (never compared the tech data sheets, and don't know if they even are different), but by using cleaner, better sorted materials, it likely is. Unless you are planning something like black grout, white thinset tends to work quite well for most anything.

johnfrwhipple
06-25-2012, 07:06 AM
Jim I also think it has something to do with "Fly Ash (http://www.nrmca.org/research/cif%20spring%2008%20fly%20ash.pdf)".

It appears that the cement industry is using more and more of this and it's hard to know what the Portland ratio is in relation to "Fly Ash" ratio. I have heard in my Mapei training classes that this is generating huge problems on commercial projects and Mapei has recommended to me that I inquire on the cement type and mix ratio for any commercial project.

I'm not sure if companies like Laticrete, Custom, Mapei or the like use any "Fly Ash" in their production or if they even know it's included perhaps with a portland cement order.

jch
06-25-2012, 01:46 PM
Thanks. Turns out the data sheet I need is the one that doesn't use Keralastic as an additive, just Kerabond plus water:
http://www.mapei.com/public/CA/products/Kerabond_TDS_EA.pdf

Based on what you've both said, I'll get some Ditra and a bag of Kerabond White (for both over and underneath the Ditra).

Trowels:
- How does 1/4"x1/4" square trowel sound for using to bond the Ditra to the SLC with Kerabond?
- What size trowel do I use on top of the Ditra when installing my 12" x 24" porcelain tiles? 1/2" U-notch?

How do I know if I'm using the right sized trowel? i.e. how do I know when I've got the wrong size during the job?? (V, square, U-notch)?

Thanks!

chefwong
06-25-2012, 04:52 PM
Water with Kerabond keeps it unmod.
Keralastic with Kerabond makes it mod.

1/4 x 3/16 V notch for Ditra

12x24.
Try to use a medium set thinset.
I like a 1/4 x 1/2 for that sized tile - U notch

johnfrwhipple
06-26-2012, 06:40 AM
Water with Kerabond keeps it unmod.
Keralastic with Kerabond makes it mod.

1/4 x 3/16 V notch for Ditra

12x24.
Try to use a medium set thinset.
I like a 1/4 x 1/2 for that sized tile - U notch

Like setting anything you need to ensure you have proper coverage under the Ditra. I find that the V Knotch trowels don't cut it with a Ditra install myself.

Personally I like to use a 1/4" x 1/4" trowel for the first pass. This leaves a good amount of thin-set (too much) but allows the Ditra to get well coated. We have a Ditra Trowel and after we pull up our Ditra we comb it with the proper trowel. This two step approach gets full coverage under are Ditra every time.

After all that work you do not want to have only 60% coverage under your Ditra. I also don't like over watering my setting material and find it is too hard to get proper coverage onto Ditra if you mix your thin-sets as per the manufacture's instructions.

On Occassion when it's hot we will even back butter our Ditra and lay it over trowel lines.

It's easy to tell if you have proper coverage. Just lift it up and look.

Using something to weigh the corners down is a good idea to keep the corners from curling up.

jadnashua
06-26-2012, 05:42 PM
FWIW, the texture and consistency of any thinset will vary a HUGE amount depending on how it is mixed. A decent paddle, proper RPM, and duration is critical. Most people mix until it looks good, but that may not be right. Sometimes, the use of a timer, and rechecking the RPM available can make a big difference. The shape of the paddle can make a big difference, too. Some end up putting too much air in the mix, which affects it.

dlarrivee
06-26-2012, 09:32 PM
I think those small cracks are plastic shrinkage cracks and you could find similar cracks on almost every single monolithic slc pour if you got out a magnifying glass, no?

jch
06-26-2012, 11:49 PM
I took out the toilet drain stub tonight and then could see that the cracks go all the way through the SLC.

Also, now that it's been 10 days, no more new cracks have appeared. Now I can see a pattern--they're approximately over top of the structural members--joists and blocking. Which tells me the 3/4" T&G exterior ply is "hammoking" between joists.

Regardless, the SLC is firmly bonded to it.

Put down the Ditra tonight--using their 4.5mm square notch trowel--worked really well. Thanks for all the advice.

For laying the 12x24" tiles, do I make all my cuts before I start thinsetting them down? Or do you recommend I cut as I go??

jadnashua
06-27-2012, 05:31 AM
Gluing the subfloor to the joists when nailing or screwing it down can help a lot with this. What you see is one reason why they require TWO layers of ply for natural stone installations. The edge of a board will act like a lever when there's deflection between the joists. That's also why you don't line up the joints on sheets - the top layer should be 1/4-span past a joist. This can also happen if the subfloor is not installed perpendicular to the joists, as it is much stronger across the joists due to the face grain. If your joist spacing is within specs, you'll probably be okay. Ditra can help if the subfloor is within specs. This is one reason a lot of pros like to install a second layer of ply regardless of whether it is for ceramic or stone. INdustry standards call for a minimum of 5/8" ply on 16"oc joists, but again, most people don't like the minimum, as it leaves little margin for error.

As long as there's no vertical displacement on the cracks, you should be okay.

Precutting sort of depends. Any little miscalculation can be exagerated when setting. On a small room, probably not a big deal - it can be huge on a large install. Off by 1/32" over a row of 32 tile, is an inch, which would likely be unacceptable. But, if you have layout lines and are constantly correcting as you go, it's not as big a deal. Depends on how many, if any, critical things you have in the middle. If it is a clear, unobstructed job, since you need a gap at the edges, being off a little isn't a big issue as long as the baseboard will cover it.

jch
06-27-2012, 07:36 AM
That's what's puzzling about this.

- I glued and screwed the 3/4" exterior t&g ply to the joists and the blocking using deck screws and construction adhesive (PL400)
- I ran the ply's face grain perpendicular to the joists (see photos earlier in thread)
- the cracks are not at the plywood joints--instead they seem to roughly follow all the joists and blocking
- I have a layer of 1/2" ply that I was about to install over the 3/4" (using the staggered offset you describe) but the TCNA and Ditra manuals convinced me that it wasn't necessary. In hindsight I should've eaten the extra headroom and used it. I won't know until the tile is installed over the Ditra whether this was a critical error.



On another note, I mixed 1/3 bag of thinset when putting down the Ditra and it wasn't enough. Had to stop part way through and mix more (which is much harder than mixing entire bags).

Trying to figure out whether I should continue to mix small batches and cut tiles as i go when laying the tile or whether I should precut a bunch so I can lay a lot at once.

Would it work better to lay the uncut field tiles first in one big batch, then go back and do the cuts for the perimeter tiles and then lay them as a group???

chefwong
06-27-2012, 05:12 PM
Depends on what works for your flow....

You could consider installing ditra, prefilling the waffles, run your chalk lines and then decide on a starting point and lay that tile true.

johnfrwhipple
06-27-2012, 11:28 PM
Always better to mix your setting materials in smaller batches as you go. If you open the bag up most drill bits will fit into the bag so you can dry mix your thin-set. Make sure to follow the mix ratio's when you mix small lots.

jch
06-28-2012, 05:49 AM
I don't know whether I'd have the nerve to run my mixing paddle in the dry bag... Visions of tearing through it and having powder everywhere. :-)

But I agree that it'll end up being small batches. It just seems to put a lot of air into the mix when there isn't enough to completely cover the mixing paddle. I'm using a Makita fixed-speed mixing drill (600 rpm) with a double-box paddle.


In terms of layout/lippage, leaning towards using QEP's LASH system with 1/8" spacers. Tiles are 12x24" porcelain, rectified, with a beveled edge:


Would it work better to lay the uncut field tiles first in one big batch, then go back and do the cuts for the perimeter tiles and then lay them as a group???

In particular, if I did it this way, how would I minimize lippage between the uncut field tiles that i set initially and the trimmed perimeter tiles that I set a few days later? Do I install LASH ties on the perimeter edge of the field tiles during the initial set so they're there for when I install the perimeter tiles??

jch
06-28-2012, 11:26 AM
In terms of layout/lippage, leaning towards using QEP's LASH system with 1/8" spacers. Tiles are 12x24" porcelain, rectified, with a beveled edge.

In particular, if I did it this way, how would I minimize lippage between the uncut field tiles that i set initially and the trimmed perimeter tiles that I set a few days later? Do I install LASH ties on the perimeter edge of the field tiles during the initial set so they're there for when I install the perimeter tiles??

I just called QEP and they told me this:
- When ending a row for the day, make sure your edge tiles are level
- Slide some LASH wedges under the free edges to support the tiles at that orientation
- Once they're supported, use a LASH clip to dig out the still-wet thinset from where the clips will be installed when you resume tiling.
- Don't leave these clips there--you won't be able to get them straight enough. Just make room for them.
- When you resume tiling, slide some fresh thinset under the existing tiles' edges (where you tunneled the thinset out previously), install a LASH clip, and continue tiling.

I haven't tried it, so I'm not sure how much of a pain this would be, but that's their recommendation.


So, would you people recommend for or against my idea of setting all the full-size field tiles in one pass, waiting a couple of days for it to set, then measuring and cutting all the perimeter tiles?

johnfrwhipple
06-29-2012, 06:27 AM
I've done this before. It is a solid plan of attack. You might find it's nice to break up the routine by cutting some tiles.

Just start and see how you feel - there are no tile police going to be checking on order of events.

One thing to remember with those Lash clips is that they do hold the tile a little of the floor so if you have a corner where the tile needs to be quite tight to the floor you may need to trim the clip bottom. The Raymondi system is similar to lash but a little flatter - I've just not seen it sold here in BC.

JW

jch
06-29-2012, 06:35 AM
Thanks. I think I'm having problems with whipping too much air into my Kerabond thinset.

I'm using a fixed-speed Makita 1/2" mixer drill and the double box paddle that came with it.

Instructions on the bag say: mix 5 minutes at 250 rpm, slake for 10 minutes, then mix for another 2 minutes.

My mixer only goes at 600 rpm and the thinset seems like whipped cake batter by the time I've run it for 5 minutes, especially on a small batch.

Should I change to a different paddle? If so, what type?

Walking on the 2-day old Ditra, I'm getting crinkling sounds, which to me sound like the thinset underneath crumbling(!).

johnfrwhipple
06-29-2012, 06:41 AM
Try mixing for four minutes and then mixing by hand for one. Use a broom stick and hold the bucket between your knees while your kneeling.

When we mix we do so like this;

1). Read the instructions! Then. We add all the liquid and one half the thinset and spin it for a half minute. This makes a very wet slurry coat.

2). Then we add in 25% more thin-set and spin it again for 30 seconds. Stiffer but to thin still

3). Then we add in the last 25% slowly will mixing.



If your adding to much air you might find that your working time is dropping. The second mix is to extend the working times. How does your working time fit with the printed instructions?

The crinkling sound might just be the Ditra itself. There are air pockets between those dovetails.

jch
06-29-2012, 06:51 AM
Maybe. It just seems like the second (smaller) batch I mixed is more crumbly. Kerabond White with water. Trying to follow the bag instructions to the letter.

Would an egg-beater paddle be better than the double box when mixing thinset??

johnfrwhipple
06-29-2012, 07:26 AM
John it's hard to determine what you got there without seeing it and feeling it. You should never have any thing rocky or crumbly in your thin set.

Did you check the date code on the KeraBond?

Is the product store right and not wet?

Can you post a video of your mix?

JW

jadnashua
06-29-2012, 07:49 AM
600 RPM is just too fast, I think, regarless of the paddle you use. They recommended a paddle shaped more like a spiral when I took the class. Too much air will also make the stuff weaker.

jch
06-29-2012, 09:38 AM
Thinset is very smooth after mixing. The crumbliness/crinkle sounds appeared 2 days later when stepping on the bare Ditra (with thinset underneath).

Date code says it was manufactured this month. Used it the day I bought it.

Unfortunately, the mixing drill I bought only has one speed: 600 rpm. It's the Makita 6013BRX1 kit sold at home cheapo. http://www.homedepot.ca/product/makita-drill-w-bucket-mixer/969317

Now what? I can see if I can get a spiral paddle....

jch
06-29-2012, 08:10 PM
The Mapei rep said to talk to Schluter. Schluter said the sound means that the fleece is not embedded in the thinset. Told me to cut a 1 foot square and try to peel up the Ditra--to see whether the whole square would come up, or whether the orange plastic would pull off its fleece backing.

The whole square came up, fleece and all. :-(

Coverage was 100% and you could see the grid pattern in the thinset, so mechanically it was installed right.

Schluter told me the problem was that I followed the mixing ratios on the thinset bag (!). Even though Mapei's instructions say "do not over-water", Schluter wants me to add so much water that the thinset ridges slump when troweled.

Ripped up the entire membrane (which stretched the plastic so that it would no longer sit flat). Schluter comp'd for free replacement Ditra :-) so now I just need to figure out how to get the floor flat before I reapply a membrane.

The original thinset (kerabond unmodified) is now 2 days old.

**What's the best way to remove it so that I'm back down to my nice smooth flat SLC layer?? I bought a big scraper, but it's really slow going....

johnfrwhipple
06-30-2012, 07:34 AM
John are you serious! Unbelievable. And people wonder why I have so many issues with Schluter.

Good on them for replacing the Ditra but ask Schluter for a better water ratio mix. The boys and techs from Mapei are not going to tell you to over water their thin set so you will need Schluter's help on this.

As for the best way of removing the old thin set try placing a wet rag over a section for an hour and then using your scraper. Before you layed the Ditra was there any places at all the cable heat was proud of the finished floor height?

How much thin-set did you spread when you layed the Ditra?

Is the floor heat on or off? Off is the correct answer.

Your bonding issue and the over watering of thinset is one of the reasons we don't use heating mats or heating blankets. I have heard of similar failures with the bonding issue.

I feel for you John. Sorry to hear that. Thank God you found it before you layed all the tile....

It might be a good idea to lay the next round of Ditra down in smaller sections - say 3'x3' squares.

Did you roll the Ditra? Did you walk on top of it while installing? How strong are you? How much do you weigh?

When installing Ditra, Kerdi, Tile, Noble, Wedi and anything that requires thin-set remember that you need to check the coverage rates. Lift up the Ditra and check the coverage, then re-set it.

JW

jch
06-30-2012, 08:02 AM
Yes it was good of them to replace the Ditra, although there's no way I was going to shell out for a replacement when I was following the thinset manufacturer's directions... I would've switched to a competitor's product.

Schluter said to add water to the Kerabond until it's like yogurt--will hold ridges but they'll slump. When I said that Mapei says not to overwater it, they said it's not overwatering--it's just being at the top end of the water range...(!)

When laying the Ditra the first time, I pulled up the Ditra and it had full coverage stuck to the underside. The pattern on the thinset now on the floor confirms that I had full coverage (no trowel lines), but I suppose it wasn't wet enough to actually soak through the weave of the fleece.

I used the official Ditra 4.5mm square trowel.

Floor heat has never been on.

I used a float to embed the Ditra in the thinset. There is a very strong grid impression in the thinset, so mechanically I think I did everything according to Schluter's instructions. The problem seems to be that stock Kerabond won't wet Ditra's fleece enough for a strong (and quiet) bond.

I'll try the soaking methods for getting the old thinset up. My Novaplan Easy SLC is grey (covering the heating wires) whereas the Kerabond is white, so it should be easy to tell how far to scrape.

Interestingly, the hairline cracks in the SLC have *not* telegraphed through the thinset... Maybe I don't need an anti-fracture membrane after all ;-)

johnfrwhipple
06-30-2012, 08:15 AM
I wish you lived in North Van. I would hit you up for a case of beer and we could bang this floor out in an hour or two!

I helped Dave Randal from Mapei build his son's shower here in North Vancouver. We worked on it a couple of days but Dave did all the work - I just helped with the linear drain install. One thing that impressed me the most about Dave was the care he took in measuring the water content. He measured exactly and told me that these thin-sets, concrete repair products and grouts are "Exact Science" the water range is all you have to work with.

When you over water concrete you weaken it. The art here is finding the happy medium between overwatering and strong enough and water properly and no bond with the Ditra. It bothers me that this information is not made available from Schluter. Why can they not specify the water mix?

Perhaps switch to a 1/4" by 1/4" trowel for the next install. Get the Ditra set, stand on it and slide back and forth - this will be too much thin set but straight away you can left up the Ditra and then re-comb it with the proper trowel.

Or screw Schluter and there warranty and use Grani Rapid from Mapei.

Or call on Ardex and ask for a thinset recommendation for Ditra with a friendlier water ratio.

Or use some stucco mesh and call it a day.

Or, swing by my place for some Noble Seal TS - It is harder installing Noble Seal TS than Ditra though.

Your so close. I don't doubt for a minute that this stage will get the best of you. Push on man. We are waiting for finished pictures...

JW

dlarrivee
06-30-2012, 08:21 AM
Mapelastic CI?

jch
06-30-2012, 09:37 AM
This is what the thinset looked like when I set the first 2/3 of the Ditra. Notice that it holds notches:
16677

and the first 2/3 down:
16685


2 days later, there was a crackling/pop-rock sound when stepping on the Ditra or when rocking back and forth on a 12x24" tile laid on top of it. Schluter told me to cut out a square of Ditra and try to peel it up. They were hoping that the fleece would rip off the back of the orange plastic. Unfortunately, that was not the case. Notice how the coverage is quite good:
16679

After peeling all the Ditra up (and stretching/ruining it in the process). The new Ditra is on the left. The pulled-up Ditra is on the right. Notice how coverage on the floor is good and that the grid pattern is very prominent from pressing the Ditra into the thinset.
16683

johnfrwhipple
06-30-2012, 09:53 AM
John that is not going to work.

When you pull back the Ditra it needs to have the thin-set squished into the fibers of the fleece. It is hard to spread it all out, line up your trowel lines and lay without the thin-set skimming over. Better to place a wack of it on the floor, flat trowel or burn it in and then let it dwell while you do this. Then scratch your trowel lines while you roll the ditra into posiiton.

I've seen so many 'Pros' mixed their setting material so they can pour it out of the bucket. I do not like this approach but it's easier - not better - easier.

Is there a bond breaker on the back side of the Ditra? Did it get dusty?

Try a sample piece like I mentioned above. See if you get a good coverage rate. I'll bring in some Ditra to work today and show you a coverage check on some scrap drywall.

Work on prepping the floor and do another test. Use an off cut and some scrap cement board or drywall to get a feel for it.

Working in smaller sections might help you get the product down faster.

JW

jch
06-30-2012, 12:38 PM
I tried wetting some of the old thinset--it makes it less dusty to scrape, but is really thirsty.

Now I'm wondering whether it would help next time to mist the hardened thinset, trowel on new thinset, then mist the back of the Ditra before rolling it out.

Would a damp fleece help the thinset bond better??

jadnashua
06-30-2012, 04:31 PM
The fleece bond strength is around 75#, the 'perfect' thinset is around 250-300#/sqin. Overwatering it enough to embed the material won't hurt with any similar membrane but it can't be soup. Now, on top of it, to a tile, it is MUCH more critical to get a good mixture. The membrane to tile bond should be max, if possible even though the membrane would release first you want full coverage and a good bond to the tile. The dovetails will lock it into the membrane if filled properly. There, the consistency of the mortar needs both bond strength and compressive strength for best effect.

johnfrwhipple
07-01-2012, 09:16 AM
I tried wetting some of the old thinset--it makes it less dusty to scrape, but is really thirsty.

Now I'm wondering whether it would help next time to mist the hardened thinset, trowel on new thinset, then mist the back of the Ditra before rolling it out.

Would a damp fleece help the thinset bond better??

John I got nothing for you. I have not tried to do this before.

When you installed the first round of Ditra how long did it take you to set it inplace? Was there a draft or anything that could have made the thinset skim over?

If Schluter and Mapei won't recommend a water mix why not ask Jim. Jim should John overwater his thin-set by 10%, 20%.

It is truly amazing the effect an extra handfull of water has on a five gallon bucket of water. Maybe try 5% added water and do a test run. Perhaps set one 3'x3' square and then start the tile in the tub surround. This should give you a few days to see the effects of this added water mix.

I never got to that test sample for you John but I will try and find a good picture showing the coverage.

So few examples online of checking for coverage on the back side. I thought I would find more references but did not. http://www.go-tile.com/advice_ditra_matting.php This link has a good picture of the proccess but not so close up you can see the floor.

http://i839.photobucket.com/albums/zz314/jfrwhipple/Proper%20back%20coverage%20for%20Noble%20and%20Dit ra/NobleSealTScheckingforcoverage.jpg
http://www.facebook.com/photo.php?fbid=433680849990809&set=a.433680769990817.118951.258556230836606&type=1&theater

If you look at this picture you will see the floor coverage and the little spikes it makes when the membrane is lifted off the floor.

Checking for coverage when tiling is key as well.

JW




JW

jch
07-01-2012, 10:11 AM
I had full coverage on the back side of the fleece when I tested it, but it wasn't spiky like that! So definitely need to go with at least some more water in the mix.

Question: The first layer of Kerabond thinset is so firmly attached to the SLC that I can't get it up with a scraper. So I've used the scraper until it's smooth and as close to level as I can get.

Do I need to *mist* this existing layer of thinset before I apply the next layer?? I'm concerned that it'll suck all the moisture out of the new thinset.

btw, there were no drafts/sunshine when I put down the Ditra originally. There was less than a minute between applying the thinset, trowelling, and rolling down the Ditra -- very fast -- so I don't think it could have skinned over. The whole room took less than 20 minutes, applying thinset as I went.

johnfrwhipple
07-01-2012, 11:02 AM
John I'm not a mister. I like to use a sponge with clean water and clean the surface. Make sure you vacumm well and then wipe it down with a sponge. You can't soak the floor or the water will further weaken the thin-set. We like to load up the section we will be installing with thinset and burn it in. Then just before laying the Ditra comb your ridges. I walk on my installs straight off and then switch to my roller or 2"x4". Lift a corner, check your coverage and once OK'd move to the next section.

Once layed we try to not walk on the fresh Ditra until the next day. And even then we often lay out scrap boards to walk on. Do not vaccum your Ditra install for a couple of days since you can pull it up.

JW

jadnashua
07-01-2012, 08:44 PM
The best and only real way to tell is to apply some, install the membrane and see if it is getting properly embedded. Once you do this a few times, you'll recognize when you have the proper mix. It might take as little as a half-cup - it might take more or less. It can't be soup, and as said, it must be properly mixed with a decent paddle at the prescribed rpm. Excess air entrainment IS a problem. I don't remember the max value, but think it was in the order of 10%. It's easy to get MUCH higher values if your drill motor is too fast or the paddle isn't optimal. And, because on smaller batches, a large paddle may not be entirely submerged, you will get more air entrainment than if it is fully covered.

Also note that, while it doen't happen all that much, if you mix a partial bag, you might be getting different results depending on how it was mixed at the factory and how it was shipped. Things can settle, and there's no guarantee the top of the bag has the same mix as the bottom, only that you have the right proportions of ingredients in the whole bag. My projects have always taken me too long to use a whole bag at once, either from the complexity of things or the smaller areas. This means that I'm mixing partial bags of thinset almost all of the time. I tend to use a bathroom scale good to around 0.1#, and calculate the water accordingly. That gives a good starting point.

jch
07-01-2012, 08:58 PM
Yah, I've been doing the bathroom scale and measuring cup thing too...

After cutting the replacement Ditra to shape, I decided to take a break today and instead mixed up some Synko Concrete Fill ("con-fill" as the contractors here like to call it) with my new egg beater paddle. Con-fill has got lots of fibres in it (for strength) and is great for filling holes/gaps up to 1" in concrete board (HardieBacker in my case) and for bringing crooked pieces back into plane with each other. It doesn't shrink and is rock hard in an hour -- great stuff!

Next up I'll tape the seams on the HardieBacker with alkali-resistant fibreglass tape and embed it in some thinset.

After that's all done, I'll return to the floor and the Ditra.

Gotta say this egg beater paddle traps a lot less air than the double-box one did -- probably because it's only 5" in diameter, instead of 8" -- a big difference in speed when the drill can only go at 600 rpm.

johnfrwhipple
07-02-2012, 09:03 AM
Yah, I've been doing the bathroom scale and measuring cup thing too...

After cutting the replacement Ditra to shape, I decided to take a break today and instead mixed up some Synko Concrete Fill ("con-fill" as the contractors here like to call it) with my new egg beater paddle. Con-fill has got lots of fibres in it (for strength) and is great for filling holes/gaps up to 1" in concrete board (HardieBacker in my case) and for bringing crooked pieces back into plane with each other. It doesn't shrink and is rock hard in an hour -- great stuff!

Next up I'll tape the seams on the HardieBacker with alkali-resistant fibreglass tape and embed it in some thinset.

After that's all done, I'll return to the floor and the Ditra.

Gotta say this egg beater paddle traps a lot less air than the double-box one did -- probably because it's only 5" in diameter, instead of 8" -- a big difference in speed when the drill can only go at 600 rpm.

Concrete Fill is used for drywall not tiling. I have never used it on a backer board install.

Why did you not just use thin-set?

1" holes in your backerboard?

Oh man. We better look at this....


JW

jch
07-02-2012, 11:00 AM
Thinset shrinks too much. I've got a lot of sharp angled corners (slanted ceiling) that don't work well with the "score and snap" approach to trimming HardieBacker. And trying to trim 1/2" off the edge of that stuff leaves a pretty ratty edge. Con-fill fixes it in one coat. You should try it -- works great.

edit: see 2 posts down from here....

dlarrivee
07-02-2012, 09:50 PM
Stupid question, why are you doing the floor before finishing the drywall?

Who recommended a setting type joint compound (reinforced or not), for your cement based tile backer?

jch
07-03-2012, 06:16 AM
Stupid question, why are you doing the floor before finishing the drywall?

Who recommended a setting type joint compound (reinforced or not), for your cement based tile backer?

1) Because I thought it would be easier for me to tile a floor than a sloped ceiling--start with the easier part first then do the other. Also in no big hurry so could let the floor cure before moving on to the walls. That said, I'm now focusing on the walls/ceiling and will resume the floor once the walls are taped.

2) A contractor friend recommended con-fill for fixing spots where the HardieBacker had not snapped cleanly (corners etc.). From the name, I was assuming that it was primarily cementicious. However, having used it now, I see that it is plaster of Paris based, with some cement in it.

This could be a big disaster when I apply thinset over it--it could soften.... Now I'm hoping that the layer of AquaDefence will make this a non-issue when I'm installing the tiles. However, during the taping phase it could still be a problem. We'll see.

So much advice, so much to learn.... Appreciate all the help.

johnfrwhipple
07-03-2012, 07:44 AM
John - I'm glad your still plugging away at this and sharing your progress.

Cement Fill rocks up hard but really is not a proper backer material - that said if you can achieve 80% contact on sound backer board you will be alright. AquaDefence does stick and dry to cement fill. Once the Aqua Defence dries it will not reactivate the cement fill and make it mushy.

To add strength to these areas do you have any stucco mesh?

JW

jch
07-03-2012, 10:14 AM
No mesh -- there are only a couple of spots inside the wet area that I used it -- to fill in broken off edge chunks of HardieBacker (1/4" x 3/4") and along the top edge of the shower head wall (where it meets the ceiling).

I extended HardieBacker into the dry part of the room (long story) so there I used the con-fill to skim areas that weren't perfectly in plane with each other and to fill some gaps where it met a non-true existing wall. None of these dry areas will be tiled so thinset compatibility is not an issue there.

We'll see how it stands up when I'm taping with thinset... Worst case it'll turn to goo and fall out, in which case I'll just replace with a few applications of thinset.

Still nice stuff to work with though :-)

johnfrwhipple
07-04-2012, 10:28 PM
I'm a fan of the cement fill myself John.

If you have some Aqua Defence you might try giving the cement fill a coat before thin setting. Nothing sticks to drywall compound that well. I have been trying different primers over drywall for some time looking for a good solution and have found that the Planicrete AC cut with water works well. The Grani Rapid liquid cut with water - not so well. I have some Mapei Prim Grip we are testing out as we speak.

I would imagine that any left over self levelling primer cut with water might work for a small patch repair. If you mock it up before hand I bet you find you get a better bite with both Aquadefence or thin set once these areas are primed.

Lets see some more action shots. I like pictures!

JW

jch
07-04-2012, 11:11 PM
Sometimes it's super-handy having a little guy in the house who knows how to tape and mud!
16739

jch
07-05-2012, 04:18 PM
Just did the taping and mudding in the shower area. Lessons learned:

1) Not all Fiberglas mesh tape is created equally. QEP Board Seam Tape is horrible: the glue is weak, the fabric is flimsy, and it just doesn't stay in place while thinsetting. Durock Cement Board interior tape is the opposite: sticky glue, sturdy mesh, and stays in place while thinsetting. No contest.

2) Mapei UltraFlex LFT works great over top of Synko Concrete Fill compound. No primer needed. Stuck just as well to the con-fill as it did to the HardieBacker. Really easy to spread and feather when taping.

3) The same rules for taping UltraFlex LFT over HardieBacker apply as with pre-mixed mud and drywall: stick the tape along the seam, press the UltraFlex LFT on thick with a 5-inch taping knife, then scrape off as much as you can on a 45 degree angle to the tape. No discernible buildup that will interfere with tiling.

3 pounds of UltraFlex LFT did the entire wet area and gave me almost exactly an hour of working time.

All in all, a great experience. :-)

dlarrivee
07-05-2012, 09:07 PM
Sorry, I'm afraid to see the results of the mud and tape job on the drywall.

jch
07-05-2012, 09:19 PM
Ah, ye have no faith in his teacher... The little guy's workmanship is much better than the contractor we let go in December...

Here's how it looked after the little guy skimmed the far wall, and mudded the wall side of the tape on the right wall. No sanding done yet. Ceiling thinset still to be done.

16757

dlarrivee
07-05-2012, 09:26 PM
14" of joint compound for an inside corner?

Since you're teaching, show your kid how to hold the knife properly.

http://www.finehomebuilding.com/CMS/uploadedimages/Images/Homebuilding/Departments/021197bs092-01_ld.jpg

johnfrwhipple
07-06-2012, 05:15 AM
Ah, ye have no faith in his teacher... The little guy's workmanship is much better than the contractor we let go in December...

Here's how it looked after the little guy skimmed the far wall, and mudded the wall side of the tape on the right wall. No sanding done yet. Ceiling thinset still to be done.

16757

John what is this room? Is it a storage locker?

Love the use of Child Labour! My three girls are always helping me with something. My eight year old seems to love the trades the most and my youngest six year old loves working with hardwood. She helped David and I with the face nailed floors we are installing in my home. The oldest - is all about the delegation.... lol

JW

jch
07-06-2012, 10:36 AM
Wow, tough crowd... :)

It's tough to tell the scale from the picture but this is a 13" wide cubby in the bathroom. The mud is one 6" knife-width wide. This area will hold towels etc.

It's not Child Labour if you don't pay them... they're apprentices... ;)

When asked, my daughter would always say her favourite part about Grade 6 was working in the woodshop. They used to open it up during lunch to whoever wanted to use it and she and her 2 friends would go in and have the run of the place. She made some really beautiful stuff out of maple, mahogony and oak.

My son really likes making stuff too. He keeps asking whether he can have the leftover scraps of Ditra -- not sure what he has in mind but I know it'll be cool.

Everyone has to start somewhere...

jch
07-13-2012, 11:04 AM
Just about done prepping the room and finalizing the grout line placements...

What thinsets / trowel sizes would you recommend for the following? I've linked to the product pages below in case you need to see the tile specs.

1) Ames Radiance (http://www.amestile.com/radiance), 12x22" (landscape)
- Installed over HardieBacker/AquaDefense on shower walls *and* ceiling
- Thinking of 1/8" grout spacing
- Would like to use LASH system
- Considering using Mapei UltraFlex LFT White to make it easier to do the sloped ceiling -- good choice?
- What size trowel? 3/4" square? 1/2" U? something else?

2) Ames Sedona Marble Mosaic (Aspen) (http://www.amestile.com/sedona), 1x2.25" Honed Marble Mosaic on 12x12" sheets
- Installed over HardieBacker/AquaDefense on entire backsplash wall behind sink
- Mosaics are 1/8" nominal grout line (some variation)
- Includes some white marble(?) so am concerned about discoloration from thinset
- Would like to use medium grey grout (matching medium stone in mosaic)
- No idea what type of thinset to use. UltraFlex LFT White?? Something else?
- What size trowel? 1/2" square? V-notch? Concerned about thinset squeezing up between joints

3) Ames Fibra (Sage) (http://www.amestile.com/fibra), 12x24" Rectified Porcelain
- Installed on floor over Ditra
- 1/8" grout line
- grout colour same as #2 above (medium grey)
- Because it's porcelain over Ditra, I'm pretty sure I have to use an unmodified thinset like Mapei Kerabond.
- Want to use LASH system
- What size trowel? Same as #1 above?

The tile wholesaler won't be open when I'm doing this, so I'm hoping to get all the supplies I'll need up front.

Thanks!

jch
07-16-2012, 12:41 PM
I called Mapei to get their opinion and here's what they recommended for thinset types and trowel sizes:

1) 12x22" ceramic on walls & ceiling in shower over top of HardieBacker & AquaDefense:
Mapei UltraFlex LFT
Back-butter tiles (thin 1/32" - 1/16" layer with straight edge of trowel)
1/4 x 3/8" square-notch trowel

2) 1x2.25" honed marble mosaic for entire wall behind sink:
Mapei UltraFlex LFT *White*
3/16" V-Notch trowel

3) 12x24" Porcelain on floor over Ditra:
Mapei Kerabond - mixed according to package directions (add up to 5% extra water for Kerabond *under* Ditra)
Back-butter tiles
Try 1/4 x 3/8" square-notch trowel, but may need to move up to 1/2 x 1/2" square-notch trowel if not 100% coverage

Hopefully this'll help someone else whose using similar sized tiles.

johnfrwhipple
07-17-2012, 06:14 AM
I called Mapei to get their opinion and here's what they recommended for thinset types and trowel sizes:

1) 12x22" ceramic on walls & ceiling in shower over top of HardieBacker & AquaDefense:
Mapei UltraFlex LFT
Back-butter tiles (thin 1/32" - 1/16" layer with straight edge of trowel)
1/4 x 3/8" square-notch trowel

2) 1x2.25" honed marble mosaic for entire wall behind sink:
Mapei UltraFlex LFT *White*
3/16" V-Notch trowel

3) 12x24" Porcelain on floor over Ditra:
Mapei Kerabond - mixed according to package directions (add up to 5% extra water for Kerabond *under* Ditra)
Back-butter tiles
Try 1/4 x 3/8" square-notch trowel, but may need to move up to 1/2 x 1/2" square-notch trowel if not 100% coverage

Hopefully this'll help someone else whose using similar sized tiles.


Great Information John.

Thanks for sharing. You are setting the bar very high with your research. I'm sure your project will help thousands of people with question in the coming years. Well done!

JW

jch
08-31-2012, 02:33 PM
Back from vacation; just returned a whole batch of stone tile that wasn't fit for sale; and back in action.

I've coated the shower surround area with AquaDefence, but it's so dark (dark green) that I don't know what to use to mark my tiling guidelines. Black Sharpie is invisible on this stuff!

What do you people use to mark lines on AquaDefence when you're tiling??

johnfrwhipple
09-01-2012, 10:49 AM
Back from vacation; just returned a whole batch of stone tile that wasn't fit for sale; and back in action.

I've coated the shower surround area with AquaDefence, but it's so dark (dark green) that I don't know what to use to mark my tiling guidelines. Black Sharpie is invisible on this stuff!

What do you people use to mark lines on AquaDefence when you're tiling??

Give it a scratch coat of thin-set first. This will make life easier for you. The dark colour is my only beef with the product.

JW

JW

jch
10-19-2012, 10:30 AM
Floor is now done and grouted.
Stone backsplash wall is now done and grouted.

Considering using the leftover stone (0.6 x 6" stone mosaic) as a baseboard strip (a 2" high strip around the edge of the room).

Problem is that I've already mudded (with non-setting mud) the walls. I'm concerned that thinset will dissolve the mud and the tiles will fall off.

What can I do to provide a solid base for this thin strip of tiles along the floor?
- Prime the walls first?
- Paint on a narrow band of AquaDefence?
- Something else??

Surely this is a common problem... :confused:

johnfrwhipple
10-20-2012, 10:29 AM
Hi John.

Lets see some progress pictures!

If you have drywall compound on the walls already you will not get any thin-set to bite to it.

I have been experimenting with different primers and found a good one from Mapei called Prim-Grip. I would first give the drywall a primer coat with a latex or oil based dry wall primer (paint kind) - Zissner 123 or Zissner Cover Coat my favourites. For a baseboard detail you would most likely do alright with either one but if you want an even better bond pick up a gallon of the Prim-Grip (http://www.mapei.com/public/CA/products/EcoPrimGrip_TDS_EA.pdf).

The Prim-Grip (http://www.mapei.com/public/CA/products/EcoPrimGrip_TDS_EA.pdf) has sand or something in it so stir it very well. This leaves a rough texture on the wall that thinset bites to very well.

JW

jch
10-21-2012, 04:36 PM
I agree--Zinsser 1-2-3 is my favourite primer too. I only need about 4 square feet covered and Prim-Grip's smallest can is 1 gallon so I'm going to see whether the 1-2-3 will work instead.

In terms of updates, here we go...

Here's the finished floor:
17603

Here's the finished stone backsplash wall:
17604

Here's the opening for the toilet flange -- a tricky cut on the saw. Even though I knew the floor would end up thick, it was shocking to actually see how thick it was in person: 3/4" T&G exterior grade plywood + 1/2" SLC (encapsulating heating wire and plastic lath) + Ditra + 3/8" Porcelain tile:
17605

I used a laser to keep things straight and square. The LASH clips were fine when working off a wet edge, but horrible when trying to continue the next day (I did all the field tiles first, just in case it got misaligned a bit. After 2 days, I went back and did all the edge piece cuts.) With practice, lippage became a non-issue.
17606

jch
02-03-2013, 09:17 PM
Getting closer.... Shower glass is in.

18830

Still to do:
- final plumbing hookup
- stone baseboard
- mirror
- frosted glass bypass doors (and shelves) in closet
- seal grout on floor and walls (any recommendations??)

johnfrwhipple
02-04-2013, 08:35 AM
Looks like a gem John. Love the vanity

jch
02-22-2013, 09:55 AM
Looks like a gem John. Love the vanity

Magick Woods Sonata, from Home Cheapo. Despite that, I like it too :)