Hi experts! Hope you don’t mind a DIY homeowner question.
I am installing 18×18 ceramic tile in my front & back foyers and 3/4″ oak flooring on the rest of the 1st floor area. I’d like to have both floors as even as possible without the need for beveled transition pieces. My subfloor is 3/4″ OSB Structurewood which I will be covering with plywood. My dilemma is how to estimate the thickness of the thinset motar base between the ceramic tile and the concrete backer & from the concrete backer to the plywood. The tile store folks say to use a 1/2″ notched trowel to spread the thinset motar under the tile to the cement board and a 1/4″ notched trowel for the thinset under the cement to the plywood. My question is: what do the motar thickness’s typically compress down to with installation???
Here’s my estimate calculation:
Floor side:
3/4″ oak hardwood
1/16″ felt paper
1/2″ plywood
—–
1 5/16″ total height
Tile side:
5/16″ ceramic tile
1/4″ thinset motar (from 1/2″ trowel)
1/2″ Durock concrete board (and screwed down)
1/8″ thinset motar (from 1/4″ trowel
1/4″ plywood (constuct. adhesived & screwed to subfloor)
————-
1 7/16″ total height
This leaves me with a 1/8″ difference in the floor heights – which I could make up on the floor side by using 3/8″ plywood. But I’m thinking that the thinset would actually compress down an additional 1/16″ with installation. This is just a novice guess – not from real experience… so I thought I’d ask the pro’s! If the two thinset layers do compress the additonal 1/16″ I can stay with the 1/2″ plywood under the hardwood area….
thanks in advance for any comments…
Edited 1/4/2007 6:25 pm by mark14
Replies
Omit the 1/4" ply under the tile. I would install the 1/2" backerboard first, bedded in a thinned (as in a touch toward the too-wet mix) thinset bed. The another thin layer of thinset with a tile membrane, then the ceramic tile. Use Mapei Ultra-Contact thinset and a 1/2" notch trowel. Mix it a little thick so it doesn't slump, and back butter the tiles to ensure good adhesion and coverage.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Why are you installing 1/2" plywood over the subfloor in the main part of the house?
Why don't you just tarpaper over the OSB and install the flooring? The height would be somewhere around 13/16".
You could then install 1/2" durock and tile over it and you would be close to the height of the hardwood.
You are going to have to use some kind of a transition molding anyway, so a 1/16" or so is not going to be a big deal.
I'm putting the 1/2" plywood over the OSB sub-floor to give the flooring staples for the hardwood something more to grip. The house, therefore the OSB subfloor, is 19 years old. In reading multiple posts & responses on this site and others most of the comments were that even though OSB Structurewood is rated to hold flooring staples, in reality it doesn't hold that great over time (especially the stuff made 20 years ago). The recommendation was to put the 1/2" ply down for better long term holding.....Edited 1/4/2007 10:15 pm by mark14Edited 1/4/2007 10:19 pm by mark14
Edited 1/4/2007 10:19 pm by mark14
Omit the 1/4' as F/E suggested.
If new construction, read directions for Durock install, I believe they do not want you to fasten to floor joist directly. Joists shrink and you will have screws putting pressure on bottom of tiles.
I put it down with high grade tile mastic and 1/4" trowel. Goes much faster and less $ than Pl or such.
Watch that 1/2" notch trowel. That's way big, you will have thinset oozing out of the joints.
Eric
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It's Never Too Late To Become What You Might Have Been
Yeah and skip the 1/2 ply under the hardwood.
You need to rethink this.
BTW, what are yout joists sizes, length and spacing?
Uh, Oh!!
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It's Never Too Late To Become What You Might Have Been
My floor joists are 2x10's on 16" centers. They are about 13 feet in length - from the foundation wall to a steel support beam in the center of the basement. There is 3/4" OSB Structurewood nailed to the joists and I'm putting everything on top of it....
5/16" ceramic tile
1/4" thinset motar (from 1/2" trowel)
1/2" Durock concrete board (and screwed down)
1/8" thinset motar (from 1/4" trowel
1/4" plywood (constuct. adhesived & screwed to subfloor)
A 1/2" x 1/2" trowel would give an even 1/4" coverage if it was held perpendicular to the floor, which it isn't, but, the tiles will not completely flatten the mortar ridges, so it depends on the trowel operator.
As with most things unknown, it pays to do a quick experiment before committing to anything.
The thinset under the backer board will squish down to nothing where the screws are tightened down, so go easy on it unless you have an uneven floor and need it. I like a 1/8"x1/8" trowel and use thinned thinset as was recommended earlier. It's just a filler between backer board and floor so the expensive modified thinset doesn't gain you anything here--save the money for the best quality (most flexible) thinset under the tiles.
Large tiles need a stiff floor since they cover a large area and easily break if the deflection is too much. The best quality thinsets designed to allow more flex are the ticket.
If a tight line is strung just above the floor (a 16d nail is a good spacer) you can determine how much flex your floor has by simply walking on it and comparing the deflection in various places. You may be surprised at how much flex many floors have and if you have an especially spongy floor the large tile may be a problem down the road.
Best of luck!
Beer was created so carpenters wouldn't rule the world.