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Discussion Forum

Laying plywood before tiling

caplacq | Posted in General Discussion on November 12, 2008 02:44am

I’m going to tile my kitchen floor which is 1/2″ plwood layed on 2X4 sleepers on a cement slab. I plan on putting another layer of 1/2″ plywood before tiling it with 16×16 tiles. Would there be any benefit to putting a layer of tar paper down over the original layer of plywood before installing the next layer. Kind of a moisture barrier? The floor does get cold in the winter.

Paul

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Replies

  1. MikeHennessy | Nov 12, 2008 03:08am | #1

    First, tile usually wants more than 1" of ply -- I'd use at least 5/8", and probably 3/4" for the top layer. Second, I assume the slab is on grade? If so, I'd lay poly under the sleepers to keep any WV from the slab out of the flooring system.

    Mike Hennessy
    Pittsburgh, PA

    1. caplacq | Nov 12, 2008 06:21pm | #8

      The house was built that way back in 1964. I'll upgrade to 5/8" ply as you and someone else suggested. The floor is pretty solid to begin with. And my boss(wife) want this done by Thanksgiving, wish me luck.

      Paul

      1. User avater
        rjw | Nov 12, 2008 11:18pm | #9

        The roofers felt might/would act as a slip layer - aka an anti-squeak layer - you could also use rosin paper.Be sure to use a backer board and, for tiles that size, the stiffer the sub-floor the better.

        "Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."

        Howard Thurman

        1. User avater
          Joe | Nov 13, 2008 12:51am | #10

          OK, here's the $100 question. . . If you have a slab with no moisture problem, why are you laying down plywood to install a tile floor?Since tile floors hate movement of any kind, I'd deep 6 the sleeper plywood affair and install to the slab. http://www.josephfusco.org
          http://www.constructionfourmsonline.com

          1. Shep | Nov 13, 2008 12:57am | #11

            Good point.

            Why keep building up layers to get a good tile base, when you've already got one waiting for you? Plus it'd be cheaper, what with not having to buy plywood and cement board.

          2. arcflash | Nov 13, 2008 03:29am | #14

            Holy ####, I read through ten posts wondering the same thing! If anything, it will be cheaper, but also, a nicer finished product. That plywood will wreak havoc on your joints when all that wood starts to shrink.

          3. Scott | Nov 13, 2008 04:37am | #15

            Took the words right out of my mouth. Unless there is some sort of thermal insulation issue, why not just stick the tile to the concrete with thinset?If ever it needs to be removed, a garden spade works wonders.Joe Fusco... I remember your name from about 10 years ago on BT (the fiery old WebX days) Been away a while?Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”

          4. User avater
            Joe | Nov 13, 2008 05:07am | #16

            I be he, the Scott I knew went by the handle maddog if I recall correctly. . .http://www.josephfusco.org
            http://www.constructionfourmsonline.com

          5. Scott | Nov 13, 2008 05:30am | #17

            >>>I be he, the Scott I knew went by the handle maddog if I recall correctly. .No, that would be Maddog Maglin (sp?)... but I was around in that era. Good times. Remember that guy with the dog named "The Crew"? Lotsa laughs and flames in those days.Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”

          6. User avater
            Joe | Nov 13, 2008 05:42am | #18

            Scott,There were two one was Scott the other Frank, I still keep in touch Frank. The Scott I knew didn't hale from BC though. . .Anyway, It's good to see ya! ;-)http://www.josephfusco.org
            http://www.constructionfourmsonline.com

          7. caplacq | Nov 13, 2008 08:34pm | #19

            Im not ready to or can afford to redo the kitchen. I'm just working with whats there already trying tyo by some time. there was four layers of floor i had to rip up before i got to the plywood when the house was built.  I completely agree with you, when i do the kitchen , i will be going down to the slab and install radiant heat.  To busy trying to pay for college here in NY.

        2. caplacq | Nov 13, 2008 08:39pm | #20

          Thanks for you input. I decided to skip the tar paper since i don't have any moisture problems and thr floor is tight. Thanks

          Paul

  2. maverick | Nov 12, 2008 04:22am | #2

    not that I like the way your floor system is framed, in the end a glazed tile floor is a moisture barrier in itself

     

    1. caplacq | Nov 12, 2008 06:16pm | #7

      I agree with you on the way the floor was build. The house was built in 1964 and thats how it was done. Down the line when my kids are done with college, I'll do the kitchen over and rip it down to the slab and install radiant heat.

      Paul

  3. losh | Nov 12, 2008 04:58am | #3

    Not if you want to trap the moisture between the plywood and cement. You can see where this would lead. If you have a moisture vapor problem in the slab even tiling it will trap the moisture in between the tiles and the slab and as a result the sleepers and plywood now rot. The best way to deal with this (Not including jackhammering the slab and installing a vapor barrier and insulation underneath a new slab) is to use the 2'x2' floating panels sold at a depot store. They allow air movement underneath them. Some have installed fans to circulate this air and some areas around the edges are left open into wall cavities from which an HRV/ERV can remove the moisture vapor for you. Wether you are built on a slab, have concrete or wood walls, and how your insulation is installed will dictate the actual vapor removal method.

    1. caplacq | Nov 12, 2008 06:12pm | #6

      I don't have a moisture problem with the floor, just thought it might be beneficial. I'll skip that part. A family member just used the 2'x2' over a slab and installed a purgo floor. Came out nice.

      Paul

    2. timkline | Nov 13, 2008 01:12am | #12

      you are suggesting installing 16" x 16" ceramic tiles over 24" x 24" floating plywood subfloor tiles which have a polystyrene foam backing ?

      from the manufacturer's website:

      What finishing solutions can I use with the Barricade Sub-floor?You can use carpet, laminate, vinyl or engineered hardwood. Simply prepare your new sub-floor as you would any other. For example, lay down a 1/4" underlay for vinyl flooring.

       carpenter in transition

      1. losh | Nov 13, 2008 01:29am | #13

        No! absolutely not. the thin-set, according to the manufactures will not stick to OSB. I simply told him a better way to prevent moisture from traveling through the subfloor, floor and coating (Flooring product). In order to tile he needs an 1 1/4" minimum thickness. This is best accomplished with a 3/4" layer of exterior grade plywood, with 1/2" exterior grade (Read Douglas Fir here) laid perpendicular to the the last. I personally use Ditra or Protega as well for an isolation membrane. Funny that Shluter diagrams show the product being thin-set onto OSB but the Thin-set Manufactures say not to? But at no time was I advocating him putting the tiles on top of the 2' x 2' panels which by the way do not have a polystyrene backing. They are dimpled with a hard plastic, just like a water retarder applied to the outside of a foundation wall. The Polystyrene I referenced is best applied before a slab is poured and is used for insulation purposes. It can be laid underneath exterior grade plywood though. The 2x2 panels do not provide much insulation as far as I know.

        Edited 11/12/2008 5:32 pm ET by losh

  4. Shep | Nov 12, 2008 06:00am | #4

    I wouldn't add the tar paper. I would upgrade to 5/8 or 3/4 " ply, then nail down 1/4" hardibacker over that for the tile substrate.

    If you're tiling, the floors are gonna be cold with the tile, unless you do some kind of radiant heat. Tar paper won't do anything in this case.

    1. caplacq | Nov 12, 2008 06:06pm | #5

      I thought the tar paper would help as a vapor barrier, not for heat. I installed nu heat radiant heat blanket in my bathroom which is like heaven on your feet. i might do the same by the sink. I will probably go to 5/8 ply for added substrate.  Thanks

      Paul

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