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Discussion Forum

Is CDX fine for subfloor

chefwong | Posted in General Discussion on July 26, 2006 07:59am

I’m gutting up my floors and plan to level from the beams and put down a new subfloor. Is CDX 3/4″ fine for the subfloor ?

I plan to use BC for the kitchen area since that area will be tiled.

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  1. User avater
    jonblakemore | Jul 26, 2006 08:08pm | #1

    Yes. Just block the edges if it's not T&G.

     

    Jon Blakemore

    RappahannockINC.com Fredericksburg, VA

  2. JohnSprung | Jul 26, 2006 10:44pm | #2

    > I plan to use BC for the kitchen area since that area will be tiled.

    What kind of tile?  I'm guessing vinyl, because you're using BC.

     

     

    -- J.S.

     

  3. mike4244 | Jul 27, 2006 02:57am | #3

    You could use cdx, a better choice would be T&G plywood,OSB or Advantec.The last three are T&G products,Osb the least expensive, Advantec is my personal choice ,though most expensive of the former choices.

    mike

  4. mike4244 | Jul 27, 2006 02:59am | #4

    I forgot to mention , use a subfloor adhesive on the joists, helps eliminate squeaks.

    mike

    1. chefwong | Jul 27, 2006 06:41am | #5

      Thanks guys.
      Are these more *sound* - sturdier floors as opposed to the CDX due to the knots ?I thought BC was a good substrate for tile ? I may or may not use a CBU ontop of the subfloor where the tile is.... What would the recommended grade be for tile then ?

      1. User avater
        JeffBuck | Jul 27, 2006 06:41am | #6

        concrete backer board or ditra.

         

        Jeff    Buck Construction

         Artistry In Carpentry

             Pittsburgh Pa

        1. chefwong | Jul 27, 2006 06:51am | #7

          I hear ya Jeff. All I'm saying is that there still needs to be a subfloor under CBU or Ditra...It was my understanding that BC is better than CDX as a subfloor in this area due to the voids in the outer and inner plys .....I will look into the other plys that the others have recommended but BC seems to be the most $$ board the local lumberyard stocks here in Brooklyn, NYC.Lowes and HD carry the SturdiFloor product and the BC rated is $2 more than the SturdIfloor. I did not take a close look but the SIF looked like it was CD as well..

          1. User avater
            JeffBuck | Jul 27, 2006 06:56am | #8

            I see ...

            less voids can't hurt.

             

            but the real solution is to get enough wood under the backer.

            usually 3/4 + 1/2 .... then backer.

             

            Jeff    Buck Construction

             Artistry In Carpentry

                 Pittsburgh Pa

  5. blue_eyed_devil | Jul 27, 2006 06:57am | #9

    Chefwong....No...cdx is not suitable for subfloor unless it part of a two floor system.

    BC is probably not a good choice for tile either depending on what you mean by tile. Tile could be ashpalt or ceramic.

    The cdx  would be suitable for subflooring under ceramic tile, if you are going to put down a "dry pack" mud base. We used to lay 1/2 cdx subfloors all the time in my apprentice years. Over that, they lay either the mud base for ceramic or 5/8" particle board subfloors for carpeting. The latter was called a two floor system.

    The two floor system gave way to the one floor system sometime in the early 80's. Instead of 1/2" cdx subflloors, we went to a 3/4 t&G system. The toungue and groove system is critical under carpeting to keep someone from stepping down on one side of a seam and ripping the fibers in the carpeting. The seams would show up in less than a year without the t and g system.

    The t and g plywood "underlayments" also have other critical  components. The top two layers of the plywood are plugged and sanded. This prevents a lady with high heeled spike style shoes from puncturing through the carpeting into a void. Again, this would damage the carpeting or might even pose a trip hazard. Also the glues in the t&g plywoods are made of exterior properties so that they will be resistant to getting rained on. BC plywood will buckle in one rain. CDX will hold up but the knotholes are not suitable for underlayment puposes. If you block the ends to support the horizontal seams, you expose yourself to significantly more squeaks.

    I'd rethink your options...

    blue

     

    1. chefwong | Jul 27, 2006 07:05am | #10

      Hey Guys -Sorry if I was not clear.
      This is a remodel.
      I have a roof under the house already.Joist are 16" OC.
      Flooring ontop will be 3/4" Santos Mahogany Hardwood.The goal was leveling the floor - this ripping out the exisitng oak HW and pine planks. Sistering new boards to get level and then new 3/4" ply. So if the weather resistency is not an issue...is the CDX suitable or I should find some of the other plywood grades you guys have mentioned.

      Edited 7/27/2006 12:53 am ET by chefwong

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