Substitute for plywood as an underlayment? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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08-19-2001, 02:46 PM
For the life of me, I can't understand why we're using plywood as an underlayment for a surface that will outlast it(tile). Does anyone know of a substitute out there to use with cement board that is as light as ply but won't swell or warp over time? Has anyone tried Dow foam board? Thanks

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Rob Z
08-19-2001, 02:55 PM
Hi Michelle

Thanks for visiting. I'm not familiar with Dow foam board. Maybe someone else will be. Is it similar to Wedi board?

Could you give us details about your installation? (tile, setting material, who is doing the work, subfloor, etc.) We'll take it from there.


08-19-2001, 04:57 PM
Rob, I believe it's closed cell polystyrene as opposed to open cell, the stuff your new VCR, TV comes packed in. It's a really dense material.

I have seen it used as fill in a concrete slab pour, IF it's the same stuff.

08-19-2001, 07:16 PM
Dow foam board= 1" thick blue styrofoam used to insulate the out side of your house instead of plywood(plywood at corners only for support).
Frequently used under siding and as a base for drive-it.

Michelle it would not have the required support for the cement board thus would not work well.

08-19-2001, 08:28 PM
Ok JC, same stuff I referred to, but it does come in varying thicknesses, I think I've seen it 12". I'm not saying it works but maybe?

BTW, get my Email?

08-19-2001, 09:39 PM
Yes I just did Jim, too far for me though, and not really worth staying over.thx for looking out well get one one of these days.

08-20-2001, 05:20 AM
The product you are reffering to is coated with concrete and put in place similar to cement backer board.

If available in your area, it is a copy of a product that has been used in Europe for over 15 years.

It does have the compression strength to with stand residential foot traffic and is light weight and water proof.


John Bridge
08-20-2001, 06:18 AM
Hi folks,

I don't know anything either.

Michele, I don't think the Dow product has been approved for tile use. We'll take the matter up on our Professionals' Hangout board. You are welcome to participate.


Because a product will withstand foot traffic doesn't make it suitable for use under a tile installation. If that were the case, partical board would work.

Better get something going on the other board.

Rob Z
08-20-2001, 06:52 AM
Okay, everyone. I'll follow the boss's lead and take this over to the Hangout.

Michelle, please feel free to continue to post Q's about your job here. Let us know the answers to my questions in the second post.