Subfloor installation question

dknarnd · Sep 2, 2006

In the process of remodeling my kitchen and I am going to put new 5/8" plywood down over the top of the base floor, which is tongue-and-groove plank, laid diagonally across the joist. My questions are:

Do I have to leave the plywood inside the house a few days before installation to acclimate itself to the house?

Do I butt the edges up tight? The ones I tore out were tight.

Do I use ring shank nails or screws?

Installed on top of this will be a "duraceramic" tile, which is 16" x 16" tiles glued down like a vinyl so a skim coat of stuff will be installed over the plywood to fill any voids.

DWW68 · Sep 2, 2006

dknarnd
You should not have to acclimate the plywood before putting it down. Keep your joints tight. Your plywood will not expand and contract as conventional wood because of the craoo stranded sheets it is made of. Screews will hold better than ring nails (less chance of nail popping) but will be more expensive. Typicaly with an underlayment for vynal, nail every four inches arond edges and every six inches throughout center of every sheet. Check product (duraceranic) for recomendation on subfloor. Good luck with project..

MarkV · Sep 3, 2006

I would also use a sub-floor adhesive like liquid nail when you put the ply down. Besides holding the ply it will help bridge any gaps that could cause the ply to flex.

MarkV

gsganzer · Sep 3, 2006

I prefer to use the toungue and groove 3/4" plywood. If your subfloor is in pretty good shape and fairly level, then you might not need to go with something this heavy and the 5/8 might be fine. You didn't say if this is over a basement, crawl space or second story. Typically a layer of tar paper is put down between the subfloor and the decking. This is especially the case if the floor is over a crawl space or basement, to help keep out moisture. The other reason for the tarpaper is to help reduce the "hollow" sound when someone walks across the floor and to help reduce squeaks.

You said you're putting down tile. If it's a ceramic or porcelain tile, then you really need to put down a cement based backer board. The glue won't adhere well to the plywood.

You're floor "sandwich" should probably be:

Subfloor T&G Planks
Roofing paper
5/8" plywood screwed down
1/4" or 3/8" cement backer board
tile

After you put down the backer board, float all the joints with thinset and level all the low spots. A 16" x 16" tile is very unforgiving with an uneven floor. You'll probably want a fairly large notched trowel. You're tile vendor can probably give you the recommendations for your decking and notch size.

One tip that helps when laying floor tile and keeping all the tiles flat in relation to one another: Wrap and secure some low pile carpet around a 4' length of 2 x 4. As you're laying the tile "field" use the carpeted 2 x 4 and a rubber mallet to level all the tiles as you go.

EddieWalker · Sep 3, 2006

Interesting stuff. I just did a search on Duraceramic tile to see what it is and how to install it. It's not ceramic tile, but a blend of plastics and limestone that looks like ceramic tile, but is warmer to the touch and more flexible. Prices seem to run from $2.50 to$5.50 a square foot, depending on who you buy it from. Might be an interesting product.

Plywood seems like the material of choice for an undrlayment, just make sure it has a smooth, finished side. The websites said this was very important, so from that, I would want the seems to be very tight. I like to use liquid nails under all underlayment and wood subfloors. It's cheap, easy and very effective.

I'd also screw it down. A box of 2 inch screws wont cost much more than nails, but the results are far superiour. After the screws are in, I'd fill in the holes with a thinset type material. You can also buy stuff for smoothing out floors and filling cracks at the hardware store. I usually use Bondo when I'm filling prepping a floor. It's fairly cheap, easy to work with and sands perfectly smooth.

The site also said you can cut them with a utility knife. Be sure to use a framers square or something to give you a good solid edge when doing this. For inside corners, you'll need something else. I'd use a fine cut hand saw, but I didn't read all of the instructions. Mayby they mention that someplace and have a better choice of tool.

I'm very interested in how it turns out and would really appreciate some pictures and some details on what you encounter while installing it and your impressions of it after it's in.

Are you going to grout it? Seems that not needing grout is one of there selling points.

Eddie

Ken_CT · Sep 3, 2006

I recently was told that if you screw down the flooring do NOT use drywall screws. They are brittle and will snap in time. Use decking screws. I thought that advice made sense to me. Have fun.

Ken

bones1 · Sep 3, 2006

dknarnd, I used Duraceramic for my kitchen and dining room about 6 months ago.I put down 5/8 plywood with ring shank nails w/ nail gun and glue and butted the ply together. Makes a real solid sub floor.The floors squeaked very much before this but now there is rarely a squeek to be heard.The product is very easy to install and once you glue it down it will not move.I also grouted mine and it's difficult to tell from real ceramic tile.Would recommend it to anyone for a dramatic floor makeover.In my opinion it looks better grouted.

bugstruck · Sep 3, 2006

5/8" ply should be adequate but 3/4" is safer if you're thinsetting directly to the plywood as I think you are. Over older diagonal planking T&G plywood is better at bridging any inconsistencies and keeping the sheet edges flush. Screws substantially preferred over ring shank. Make sure the existing floor is well connected to the joist first. Some screws there could be helpful. Make sure the plywood is breaking over the existing joists on the butt joints. The drywall screw won't generally break in this application but they aren't the always best thread bite for wood either. A decking screw is generally preferrable. With 16" tile you need a rather level surface as others stated. Don't underestimate the need for that. If you have any humps that a 4' level is rocking on they could present a problem.

JJT · Sep 3, 2006

All good advice - deck screws, glue and 3/4" T&G plywood.

dknarnd · Sep 3, 2006

Went and talked to the people at the flooring store that sells this stuff and they said basically what has already been mentioned here in some posts; it needs to be smooth and flat. They are going to install the tile for me $7.50 a square foot installed which will include smoothing the plywood with some type of thinset type stuff before the installation, adhesive, and a sealant over the cracks when finished. We are not going to grout so that is the reason for the sealant.

My kitchen is only 10 x 15 so it's not a big project, today I tore up the old plywood and replaced it with the same size I tore off which was 5/8". There is hardwood on either side of the kitchen and with the 5/8" and the duracermaic tile my floors will be almost level. Plus I have a half wall on one side of the kitchen that I am going to warp the counter top over and the wall is finished based on 5.8" subfloor. I went through and reset almost every nail in the planks plus some screws added for good measure. I started to use decking screws but they kept stripping on me so I went to corse thread drywall screws and they seemed to work well. Before installing the sanded plywood I laid down some glue then screwed it down with 2" course thread drywall screws.