Kitchen Subflooring for Tile

Thadius856 · 05-09-2012, 07:59 PM

Planning a kitchen reno for this time next year, going to the studs in several places. While we grow the cabinetry fund, we're going to work on the flooring ad ceiling.

Sheet vinyl is going to come up for porcelain to go down. However, my only tile experience has been porcelain on top of slab, so I'm a bit at a loss for appropriate base materials. From pulling up a small corner, it looks like the previous owner just threw 3/4" OSB on top of the tongue and groove subflooring. I thought I've read that OSB isn't a suitable substrate for tile, so what will I want to replace it with?

Touching on load engineering, but are they any hard and fast rules to know if I have little enough deflection? Sitting on 4x8's 4' O.C.

gregzoll · 05-09-2012, 08:32 PM

If putting down tile, use either Georgia Pacific's DensShield or DensGuard. I used the Densshield when I did our bath floor, and loved working with it. Cuts just like regular Gypsum board. Remember though to put a bed of thinset down before securing the board with square headed Cement Board Screws. Also use the mesh tape for Cement board, when you tape the seams and then apply a thin layer of thinset over the tape and let that dry. You will be good to go then when you lay the tile. Use White Thinset when you lay the tile.

Another thing, if the floor currently squeaks, secure the sub-floor with deck screws, before laying down the underlayment.

Thadius856 · 05-09-2012, 08:54 PM

The floor never squeaks in the kitchen, but it does in a few places on the original 3/4" hardwood. I'll be sure to check it out before applying the thinset.

Any tips for keeping the thinset workable for a few more minutes? I always feel like I'm racing the clock. Otherwise, this project certainly seems within my skill set.

Am I crazy for considering tiling under the cabinets too? The kitchen's not that large and this ceramic isn't that expensive.

gregzoll · 05-09-2012, 09:05 PM

I mix it wet, let it sit for about 10 min's, and it will still be good. The trick is to add a little water at a time, until you get something like a Steak & Shake milkshake, and should still be good to go after you let it sit for the 10 min's. You should have at least 15 min's working time, if you mix it in 1 gallon batches. Just remember when you lay the tile, back butter the back of the tile before sitting into the thinset that you used the notched trowel to spread.

JetSwet · 05-09-2012, 09:34 PM

Quote:

Originally Posted by Thadius856

Planning a kitchen reno for this time next year, going to the studs in several places. While we grow the cabinetry fund, we're going to work on the flooring ad ceiling.

Sheet vinyl is going to come up for porcelain to go down. However, my only tile experience has been porcelain on top of slab, so I'm a bit at a loss for appropriate base materials. From pulling up a small corner, it looks like the previous owner just threw 3/4" OSB on top of the tongue and groove subflooring. I thought I've read that OSB isn't a suitable substrate for tile, so what will I want to replace it with?

Touching on load engineering, but are they any hard and fast rules to know if I have little enough deflection? Sitting on 4x8's 4' O.C.

Is this glued sheet vinyl? May I ask. I would replace the osb with BC ply or advantech T&G
3/4"

Thadius856 · 05-09-2012, 09:56 PM

Quote:

Originally Posted by gregzoll

I mix it wet, let it sit for about 10 min's, and it will still be good. The trick is to add a little water at a time, until you get something like a Steak & Shake milkshake, and should still be good to go after you let it sit for the 10 min's. You should have at least 15 min's working time, if you mix it in 1 gallon batches. Just remember when you lay the tile, back butter the back of the tile before sitting into the thinset that you used the notched trowel to spread.

Feel comfortable working 1 gal batches for laying the tile. It's just that I didn't think I'd have enough time for a 4x8 sheet before it got crusty. In fact, we just laid about 25 sq ft this morning. Not much, I know, but it's a small area we were doing. Here's the dry fit:

Quote:

Originally Posted by JetSwet

Is this glued sheet vinyl? May I ask. I would replace the osb with BC ply or advantech T&G
3/4"

Indeed, sheet vinyl. Very thin and poorly glued down. The bargain basement cheapest stuff they sell at Home Depot, and they still sell the same stuff, so it's probably only a few years old. Brittle in places and worn through in others. Since I can remove the OSB safely, I think I'll just use a stud finder to locate any screws, remove them, leave the vinyl on the OSB, and remove the OSB in full sheets.

Is BC ply over 2x6 TnG really necessary? If not, I'd rather avoid the added height. The T-moulding is already going to have to account for nearly 1/2" difference without it.

JetSwet · 05-09-2012, 11:10 PM

Quote:

Originally Posted by Thadius856

Feel comfortable working 1 gal batches for laying the tile. It's just that I didn't think I'd have enough time for a 4x8 sheet before it got crusty. In fact, we just laid about 25 sq ft this morning. Not much, I know, but it's a small area we were doing. Here's the dry fit:

Indeed, sheet vinyl. Very thin and poorly glued down. The bargain basement cheapest stuff they sell at Home Depot, and they still sell the same stuff, so it's probably only a few years old. Brittle in places and worn through in others. Since I can remove the OSB safely, I think I'll just use a stud finder to locate any screws, remove them, leave the vinyl on the OSB, and remove the OSB in full sheets.

Is BC ply over 2x6 TnG really necessary? If not, I'd rather avoid the added height. The T-moulding is already going to have to account for nearly 1/2" difference without it.

You will have failed tile guarantied if you tile right over the 2x6 T&G, it will flex to much even if you skim coat with thinset and even thinking of cbu board that doest add any support.

Thadius856 · 05-11-2012, 01:26 AM

Just to be certain that my current plan is workable:

Joists are 2x8 on 4' O.C. Subflooring is 2x6 TnG. Remove existing vinyl and OSB. Lay 1" engineered TnG Subflooring with coated Pan head 1-5/8" decking screws. Thinset and screw down cement board, tape and lightly thinset over seams. Notched trowel cement board and butter tiles as usual.

Any problems with this plan?

JetSwet · 05-11-2012, 12:25 PM

Quote:

Originally Posted by Thadius856

Just to be certain that my current plan is workable:

Joists are 2x8 on 4' O.C. Subflooring is 2x6 TnG. Remove existing vinyl and OSB. Lay 1" engineered TnG Subflooring with coated Pan head 1-5/8" decking screws. Thinset and screw down cement board, tape and lightly thinset over seams. Notched trowel cement board and butter tiles as usual.

Any problems with this plan?

Yes now it is did you mention the 1" subfloor in prior post?

Might want to up the size on the deck scews to be sound.

Thadius856 · 05-11-2012, 12:52 PM

Did not mention it before, no. Was at Lowe's picking up two more cases of porcelain yesterday and saw they only had 15/32" and 1" in stock. Wish they had 3/4" but oh well!

Can't upsize the decking screws too far because I have electrical grounding retrofit stapled to the underside of the 2x6 without mechanical protection, but I'll use the largest I can without penetrating straight through.

Thanks guys.