Leveling subfloors (future tile)

3 years ago

Hello--

I'm in the early stages of a DIY conversion of a walk in attic to a master bathroom in a 1950s 1.5 story home. Unfortunately the floor is anything but level - the joists under the 2nd story floor have sagged in inconsistent ways over the last 70 years and there are two layers of subfloor (wide plank running at 45 deg angles to the joists, 1/2" plywood overtop). Add it all together and it feels like a bit of a roller coaster walking around in there. Thus a two fold question: 1/ to what degree should I worry about a solid-but-not-level subfloor for a tile installation? 2/ assuming I do need to care, are there any great products out there to get the job done? I've seen other posts recommend levelers from Henry, but curious to hear options and experiences.

Thanks in advance,

-Quint

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Comments (3)

millworkman
3 years ago
It needs to be flat to within1/8" in 10', not level but definitely flat. Make sure the joist system ion your "attic" are capable of carrying the load and delection for the tile, cement and associated work as typically attics are not.
SJ McCarthy
3 years ago
In a situation like this I think sheet products (vinyl or linoleum) are the way to go. As a cork flooring expert, I would tend to work with cork glue down tiles instead of tile for this situation. The tiles are VERY light weight (compared with the tile) and the 4mm and 6mm cork glue down tiles can handle a bit of a roller coaster subfloor. The 'resilient' flooring industry is well worth a look at this.

The COST of cork glue down = IDENTICAL to TILE. If you paid a flooring pro to do this, you will pay $18/sf for the ENTIRE project. That is the cost of a cork glue down tile OR a porcelain glue down tile. The costs come in different formats....but the end result (the amount of money removed from your bank account) is identical.

Sheet vinyl is the most price advantageous...but has little hope of DIY. The linoleum (the real stuff from Marmoleum) is the MOST EXPENSIVE of the three options. Again it has no hope of DIY.

Cork glue down tiles are 100% a DIY level project. That way you can save the $10-$12/sf LABOUR costs of the installation. That goes for Porcelain tiles as well. They are DIY-able....if you are that comfortable with your skills.

I've walked SOOOO many homeowners through a glue down process. It isn't rocket science. All you need is 'prepared' plywood (which is the same for sheet products....), some cork, a chalk line, an Exact-O knife, a straight edge, glue and some polyurethane for finish.

It is roughly the same amount of effort to install porcelain and cork. The difference: 22sf of cork tile = 5 lbs. Compare that to 18sf of tile = 20+ pounds. Right. Easier to carry up and down stairs.
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Quint Van Deman
Original Author
3 years ago
Thanks folks - I guess I need to break out the laser level to get more precise with how far off things are. The joists under this area of the floor are riddled with electrical and plumbing though, so any required fixes won't be easy. While I called it an attic, it was really just an unfinished portion of the regular 2nd floor, which is running over 2x10 joists that (other than sagging a bit over 70 years) seem super sturdy. I'll report back when I have better specifics, thanks for the tips!

Leveling subfloors (future tile)

Comments (3)

millworkman

SJ McCarthy

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Quint Van Deman
Original Author

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Leveling subfloors (future tile)

Comments (3)

millworkman

SJ McCarthy

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Quint Van DemanOriginal Author

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Quint Van Deman
Original Author