Laying tile floor - what is proper subfloor?

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Kavita

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evenin' up before the durock

first, thanks for all your responses last month.

can't believe it's been a month since last visit. left behind the tiling projects for other refurbishing tasks; now returning to the tile floor and have another couple preparation questions. (yes, also listing on johnbridge.com but the responses there can be somewhat daunting!)

i considered all your input and the ply subfloor is attached to what's beneath. i appreciate your musings, intuitive and counter-, on the subject.

i'm finally about to lay the durock ...

- would you please offer suggestions for a floor levelling product to add in a couple of areas between the plywood subfloor and the durock i'm about to lay?

there's a slight unevenness apparent in a couple areas now that the ply's down and i want to correct it. i've been told LevelBest would work, but i've heard also that a mortar mix is sufficient/preferred. your thoughts? your product recommendations?

- once the durock is in place, what do you suggest using to level the areas where the durock sheets meet and a depression exists? i understand the thinset might be sufficient for this, but i'd like to hear any of your ideas.

many thanks - i appreciate your help so much.

kavita
 

Jadnashua

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Depends on how big the dips/hills are. From what I read, it is better to level after installing the cbu. If the depressions aren't too big, you can use thinset. Use the longest straightedge you have, the longer the better, and see how far off the floor is. Once the amount is known, that will help decide the best product to fix it. Self-leveling cement can be used, but it can be costly. Works great, though. Flows like pancake batter, sets quick, and makes a really nice flat floor for tiling.
 

Kavita

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thanks

jim, jimbo, don, & greg,

guess this thread can close now but want to say thanks to you all for your ideas, suggestions, referrals.

all tile sites you recommended and materials therein have been most useful.

the tile council of america handbook (tileusa.com) is a great downloadable resource.

the article on underlayment specs (the TIleLetter article) is excellent - really helped me understand that perspective.

floorstransformed.com is really easy to navigate and get answers quickly.

johnbridge.com is, well, awesome and dense with information!

ceramic-tile.com also has a wealth of helpful info - unfortunately, i have a tediously slow dial-up account and the advertising slows down any desired mobility on my end.

anyway, i REALLY appreciate your time and patience.

see you when i tile the next bathroom - this time walls and backsplash!

kavita
 

Robin Wisdom

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Garage Conversion

First, thank you so much for your web site. It is a wonderful resource for those of us who prefer to do our own work. I have learned a lot and I am so glad I found you before going forward. My house is 46 years old and on a concrete slab foundation. The garage portion (next to the kitchen) is 4 ¼ inches lower than the rest. We have tiled the kitchen with ceramic tile and now wish to continue the tile into what was the garage but will now be the laundry room. So after reading your message board I tried to come up with a plan for the sub-floor. How does this sound?
1. Build a structure of 2X3’s with 8 inches of space between the boards. The 2x3’s would be standing up on their side so that the height is actually 2 ½ inches.
2. Lay down ¾ inch exterior plywood and screw into the 2x3’s every 8 inches.
3. Lay down ½ inch exterior plywood (the opposite direction) and screw to the ¾ inch plywood but not the 2x3’s.
4. Apply un-modified thin set on top of the plywood.
5. Lay down ½ inch Hardy Backer Board leaving 1/8 inch gaps between and ¼ inch around the outside edges. Screw it down with those big backer board screws and apply the mesh tape & thin set to the gaps.
That all adds up to 4 ¼ inches which will give me the proper height. Originally I was going to use 2X4’s for the bottom structure which would have been 3 ½ inches high, ½ inch plywood, and ¼ inch backer board, for a total of 4 ¼ inches. But, after reading your message board I realized that I would not have 1 1/8 inch minimum under the tile. With the scenario above I will have
1 ¾ inches under the tile. Is that too much? Also, if you have a better suggestion please let me know. I eagerly await your response.
 

Jadnashua

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Most garage floors are not made to be level...they usually have a pitch, either to a drain in the middle, or out towards the door. Your plan doesn't take that into account, or the possible irregularities. A better solution, but heavy work, would be to level it off with a mudpack. this is esssentially mostly sand with enough portland cement to hold it together (same as what's used in making a shower pan - 5-6:1 sand/cement). You could make this dead level at exactly the height you want. It's like working with wet beach sand. You could mix it right on the floor with a (special) hoe so you don't have to transport it far. The sand is dirt cheap, and you don't need much cement. Check out www.johnbridge.com. Your plan would work (except for the possible pitch and irregularities), but keep in mind, there is no reason to use thicker cbu than 1/4" on a floor except to match up heights. CBU has very little resilient strength, and will bend (and then hold after a while) to conform to any irregularities. Good ply is better, and more is better yet. You want ply with exterior or exposure 1 rated glue, and the sides C or better (no D side(s)). T&G ply would keep the short edges supported and save having to block there as well. This stuff starts to get expensive, and time and ultimate result means a mud floor should be cheaper, and maybe faster. If you have a boiler, it would also give you the opportunity to add radiant heat tubing to keep the space nice and toasty.
 

JohnfrWhipple

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Wow.

There is a lot of information in this thread and it is all over the place. A quick scan for "how to", can leave your head swimming with details and one wrong post you read can be the downfall of your entire renovation.

There are many different ways to construct a subfloor and many requirements that need to be met. I would suggest that anyone first visit the TTMAC and NTCA websites and look there for recommended sub floor assemblies - look for one that fits your home or install the closest.

Laying 5/8" sheathing, 1/2" ply, 1/2" cement board, ditra, Nobel TS, Flex Therm Cables and on and on all finely tune the sub floor make up.

When looking for answers you should understand what deflection criteria you need. What the requirements of the tile are for install (ie modified or unmodified). What's the thinnest your setting materials can go to (ie 1/4", 3/4" etc).

This is not a simple question to answer.

I have to do many rebuilds for clients when I come to waterproof their shower. The number one failure I see in the DIY market is poor fastener and tool selection. You can't board these rooms many times with a re-chargeable 12 volt drill. So many times I come in and it was the homeowners drill had no 'Balls' and the wall boards and sheathing is moving around like crazy.

Often we will prep these rooms for not as adventurous clients and leave the tile setting to them.

Deflection.

Bond Breakers.

Look up these terms and understand them first fully. Before learning how to build your new subfloor.

Good luck.
 
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JohnfrWhipple

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With today's tile choices getting larger and larger and more and more homes being designed with open spaces - control joints, expansion joints and mortar fatigue are very important considerations.

Yet more research for you before planning your new subfloor.

This is a tricky process - the tile trade. Never have I found a one system fits all - ever.

Work with a PRO.

Look for those who are members of TTMAC or NTCA.

Hire someone with insurance.

Ask for a written description of how the floor will be built and tiled and what the time line will be. Before proceeding look into the proposed approached.

It's Easy. Fast. Quick. Weekend Project. are terms and phrases you will never hear me repeat in front of a client. Often online the advice you seek is mapped out this way.

Dig deeper.
https://terrylove.com/forums/showth...-Glue-Plywood-(EGP)-Tiling-Tips-Pros-and-Cons



https://terrylove.com/forums/showth...-Glue-Plywood-(EGP)-Tiling-Tips-Pros-and-Cons
 
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JohnfrWhipple

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Sub Floor Preparation - Wonder Board Lite over 5/8 Sheathing

Last Saturday I worked with my buddy prepping his daughter's bathroom floor for tile. There where a lot of upgrades to the bathrooms design and to cover the original sheathing we decided to go with a 1/4" layer of Wonder Board Lite. To install the Wonder Board I used Laticrete's 254 thin-set. We used 1.5" roofing nails (galvanized and a wack of them) and then tapped the seams of the boards with 4" mesh tape and more Laticrete 254.

Over this will go a Nu Heat Pad and some minor leveling....

The key points to this style of install is keeping the nails from hitting the floor joists below. Also keeping the board from bonding to the sides or bottom plates and tub are key. We kept everything back a good 1/4" to be safe.

Here you see me a few days later and I have just wiped the wonderboard lite down (after I vacuumed). Once the floor was clean and free of all debris I layout out the heating mat and cleaned both sides of this as well. Later I set it over the tub to dry. I do not want standing water anywhere - not on the mat and not one the floor.

After this was done I mixed up some Laticrete 254 thin-set. To make the mix looser I added 20% more water than spec'd. Laticrete 254 is not a low end thin-set. The choice of this premium setting material is because you do need to make a thin-set mix loose. So a great strong thin-set is still good when weakened by this over watering step. I have measure the strength of laticrete 254 in shear tests at this mix ration and the results are impressive.

Set tight to the Wonderboard Lite Sub Floor. I'll be back this weekend to cover this floor with a layer of Strata Mat and do some minor leveling for the small mosaic tile.

 
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Davidlee

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Sub Floor Preparation - Wonder Board Lite over 5/8 Sheathing

Last Saturday I worked with my buddy prepping his daughter's bathroom floor for tile. There where a lot of upgrades to the bathrooms design and to cover the original sheathing we decided to go with a 1/4" layer of Wonder Board Lite. To install the Wonder Board I used Laticrete's 254 thin-set. We used 1.5" roofing nails (galvanized and a wack of them) and then tapped the seams of the boards with 4" mesh tape and more Laticrete 254.

Over this will go a Nu Heat Pad and some minor leveling....

The key points to this style of install is keeping the nails from hitting the floor joists below. Also keeping the board from bonding to the sides or bottom plates and tub are key. We kept everything back a good 1/4" to be safe.

Here you see me a few days later and I have just wiped the wonderboard lite down (after I vacuumed). Once the floor was clean and free of all debris I layout out the heating mat and cleaned both sides of this as well. Later I set it over the tub to dry. I do not want standing water anywhere - not on the mat and not one the floor.

After this was done I mixed up some Laticrete 254 thin-set. To make the mix looser I added 20% more water than spec'd. Laticrete 254 is not a low end thin-set. The choice of this premium setting material is because you do need to make a thin-set mix loose. So a great strong thin-set is still good when weakened by this over watering step. I have measure the strength of laticrete 254 in shear tests at this mix ration and the results are impressive. You can learn more about shear testing here:

Set tight to the Wonderboard Lite Sub Floor. I'll be back this weekend to cover this floor with a layer of Strata Mat and do some minor leveling for the small mosaic tile.

 

Davidlee

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My contractor removed the original plank sub flooring and replaced with 3/4 inch plywood directly on the joists. Is one layer of plywood sufficient? I read here you need the plank sub-floor plus 2 layers of plywood?
 

Jadnashua

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John is long gone. His 'requirements' did not match the industry guidelines.

Most installers prefer two layers of ply, and two ARE required IF you're installing a natural stone tile, but not for a ceramic (porcelain is a type of ceramic). 3/4" T&G plywood, properly installed, will work per the industry guidelines and all of the testing they have done for ceramic. Now, you need something on top of it before the tile...the more common thing is a cement board (cbu), but there is NO advantage of going with anything thicker than 1/4" unless you want to raise the floor to match other rooms' heights. An alternative is to use a membrane such as Schluter's Ditra on the plywood, then the tile. In both cases, those, too, must be installed properly, and in the case of cbu, every one requires it to be bedded in thinset and screwed or nailed down then the seams taped per the instructions. It's all in the details.
 
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