Laying slate on wood flooring [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Danger DANJ
03-05-2007, 09:49 AM
I would like to lay 12"x12" slate tile in the foyer of my co-op. It's a 50 sq. ft. area with parquet wood flooring and carpet on top of the parquet wood flooring. I really don't know where to start. The carpet obviously has to come up, but what about the parquet flooring? Does that have to come up or can I install the slate over that? I asked some one working at Home Depot and they suggested to make sure the parquet flooring was solid by stapling it down and that I could lay the slate tile over that just using Versabond. That seems way too easy to be right. Can someone confirm that this will work?

If the parquet flooring has to come up, what should I use as a substrate?

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03-05-2007, 10:47 AM
Orange aprons strike again :bang:

No, the parquet is dimensional flooring and the versabond won't stay adhered very long. Pull it up and what do you have for a subfloor? How thick? Joist info...have you run the numbers on the deflecto?

Danger DANJ
03-05-2007, 12:09 PM
Yeah, I figured it wouldn't work. I figured I'd do some asking, just by some miracle it was possible. lol.

Anyway, I'm not 100% what is below the parquet flooring. Some sort of plywood I'm sure since there was plywood in my kitchen where I just installed laminate flooring this past weekend. Below the plywood is concrete. I'm on the second floor, but below my foyer and kitchen is the boiler/storage room and I know from being down there that there is definitely concrete. That is as much as I know, so hopefully that is enough to be able to tell me how to proceed. Thanks.

03-05-2007, 05:36 PM
Depending on the height considerations, you might want to tearout things right to the concrete floor. If there is plywood under the current wood floor, and it is well adhered to the concrete, you might be okay. It is likely, though, that they glued the plywood down, and there are likely voids under it. this is not good for tile, so you might have to remove it. They could have used concrete nails to adhere it. They could have installed the parquet directly to the concrete, though. Probably best to remove it and check for minor/major cracks. Check it out, then tell us what's there. If the floor is glued directly to the slab, you'd need to scrape up the glue. It must be clean enough to allow moisture to be absorbed. It might require scarcifying (grinding down to remove) the top layer to expose uncontaminated concrete.

Not all slate are created equal. Some are great, strong, hard, but some are little more than compressed mud, but still called slate. Try setting one in a pan of water overnight and then rub it to see how it stands up. A good slate will still be hard; the stuff from China and other places, might just be a soft slab of mud.

03-05-2007, 05:49 PM
Howdy Dan,

Below the plywood is concrete. I'm on the second floor, but below my foyer and kitchen is the boiler/storage room and I know from being down there that there is definitely concrete

Dan, you talkin bout the floor you're gonna tile? or the floor below??
i.e. Parquet then concrete? or Parquet then ply...
But if you're on the second floor, most likely you don't have concrete on that floor - right? :shrug:

Need some splainin.... If the floor is wood, we need to know your joist size, spacing and span for the Deflecto above... :)

Danger DANJ
03-06-2007, 09:03 AM
I see my screen name is confusing since my name is David, not Dan. Every message board I register on, the same thing happens. lol.

I went home last night and ripped up a couple of the parquet squares only to discover they are glued to some sort of padding with something that looks like tar. The padding is sitting on 1/2" plywood. I drilled a screw into the plywood and it did not hit any concrete. I feel stupid now, but in the boiler/storage room below me, the ceiling looks like concrete to me. I got in contact with the Super and he said something about the ceilings there being some kind of mesh with sprayed concrete. Does that sound right? Regardless, there is no concrete for my floor. I asked about the joists and the only thing the Super could tell me was that they are 2x8 and 12" on center. I don't know what the joist length is. How can I figure that out and also confirm what the Super told me? The building I live in was built in the late 70's if that means anything. There are 3 floors total.

So, assuming the Deflecto is fine for stone, what would I put down before the slate?

Thanks for the help so far guys. I appreciate it.

Brian in San Diego
03-06-2007, 11:23 AM

Can you cut an examining hole in the floor? That way you could measure the joists and measure the span. When you are in the boiler room I would assume you are seeing finished ceiling. If I were to take a guess the mesh and concrete spray is to insure the boiler room has a one hour (or more) fire rating. Most mechanical rooms require that rating. If the area you want to tile is directly above the boiler room you could measured the span down there. If there are no supporting interior walls down there then the span is from wall to wall (for all intents). If there is an interior supporting wall then you span is from that wall to the other wall where you want to tile. (This is a simplified explanation, but will probably suffice. If your deflecto comes out close, then you may want to get more precise measurements.) O.K., if the joist structure is sound and you want to install stone, then you need two layers of plywood with a total thickness of 1 1/4". Slate is quite as heavy as some other stones, so you could probably get away with 1-1 1/8", especially if the floor is 12" centers. The minimum dimension for your plywood needs to be 3/8" and 1/2" is better. Oh yeah, you'll need either a cbu or isolation membrane over the ply to set your slate on. Setting stone direclty on plywood is a tricky proposition and probably best left for the highly skilled or huge gamblers.


03-06-2007, 02:05 PM
I see my screen name is confusing since my name is David, not Dan

We're a pretty friendly group and try to use first names if at all possible...
Since Danger is not a common first name, the next best guess is Dan.. :)

So, assuming the Deflecto is fine for stone, what would I put down before the slate?

Not so fast young David, first things first...
Not many floors will support stone, so's we need to know the span of the floor joists.. Like Brian said, that's the length of the 2x8's (12" on centers - Need Confirmed) between walls or supports below. First find out which way the 2x8's are running and then figure out how long the unsupported span is...
Report back... :)

Danger DANJ
03-06-2007, 08:23 PM
OK. As soon as I got home from work today, I ripped up all the parquet flooring and padding under it down to the plywood. Between two sheets of plywood, there was enough space to be able to see the joists and get a yard stick down there and measure them. They are definitely 2x8. But, they are 16" on center, not 12. Then, I went into the boiler/storage room to try and find out the span. I found 2 I-beams below my apartment and the span is 9'. So it looks like my deflection would be L / 620 and not good enough for stone. :mad:

It really sucks because I just talked to my friend today and he was telling me that his job has a bunch of slate tile left over from when they had their flooring redone. I was hoping to get that for free, assuming it's still there and there was enough. :(