Bathtub installation -- order of installation (end pony wall, tub, heated floor)?

[jch]

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]

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]

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]

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.



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

[jch]

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]

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]

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]

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]

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]

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]

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.







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]

Wow.

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


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


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


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]

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]

Yup, 1/2" foam around the entire perimeter of the pour, plus 3 wraps of foam sill-gasket around the toilet waste pipe.

[chefwong]

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 !