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jpsmith 02-09-2009 11:20 AM

XPS foam board between basement slab and cement board for ceramic tiles
 
Hello! I'm currently finishing my basement and I'm seriously considering using DriCore with engineered hardwood for the main finished living space. In the half-bath and mudroom, though, I plan to use ceramic tile.

The DriCore plus the hardwood will be about 1 5/8" thick. Ceramic tile plus hardibacker will be about 3/4" thick. To make up the 7/8" difference, I'm wondering if it would work out somehow to put 3/4" of XPS foam board underneath the hardibacker, on top of the concrete slab. Does anyone know if this would work? Perhaps I'd have to fasten the hardibacker to the slab, through the foam board, using countersunk tapcons.

I'd appreciate any input or other suggestions anyone can give on this.

JazMan 02-09-2009 09:57 PM

Hi JP,

You cannot/should not install cement backers to concrete, and that goes double the way you mentioned. If the floor needs to be raised, have a tile setter do a mud-job, and set the tiles on it. Or if you're handy you can try it yourself.

You said you're going to install engineered hardwood on the DriCore. You know it has to be floating right?

Is the floor very flat? It better be with Dricore. I'd reconsider the DriCore thing.

Jaz

jpsmith 02-10-2009 09:15 AM

Thanks for the response, Jaz.


Quote:

Originally Posted by JazMan (Post 227994)
You cannot/should not install cement backers to concrete, and that goes double the way you mentioned. If the floor needs to be raised, have a tile setter do a mud-job, and set the tiles on it. Or if you're handy you can try it yourself.

OK. I remember reading that cement backer board can be used over a slab; it's usually adhered to the slab with thinset. I don't recall where I read that. Luckily, I'm not close to beginning my floor yet; I'm still gathering information. After a little more research now, I see that hardibacker should only be used over a typical subfloor, such as 3/4" plywood. This is why I'm here asking questions!

Quote:

Originally Posted by JazMan (Post 227994)
You said you're going to install engineered hardwood on the DriCore. You know it has to be floating right?

Ah, right. My original plan was to use laminate flooring over DriCore, but I'm not keen on laminates because I understand that they don't hold up well to abuse. I have two Labradors. Also, I don't like that their surface is printed on and is not real wood. I've been reading about engineered hardwood - how it's good for use in basements since it's more stable than hardwood and the hardwood veneer offers a real wood surface that wears well and can be refinished. I'd forgotten that the floor I put over DriCore must be floating. Luckily, I'm not buying anything yet; I'm just gathering info.

Quote:

Originally Posted by JazMan (Post 227994)
Is the floor very flat? It better be with Dricore. I'd reconsider the DriCore thing.

It will be flat before I put down the subfloor. There are some low spots, but it's mostly level. I'll have no problem leveling the area before I put down the DriCore. Humor me, though - if you're against the use of DriCore, what do you suggest as an alternative to use for a subfloor that offers a bit of insulation from the cold concrete and acts as a moisture barrier while losing as little finished height as possible?

Thanks!

jpsmith 02-10-2009 09:35 AM

Quote:

Originally Posted by JazMan (Post 227994)
You said you're going to install engineered hardwood on the DriCore. You know it has to be floating right?

http://www.dricore.com/en/contrac.aspx

"DRIcore is ideal for carpet and floating floors (including laminate, engineered hardwood, cork and vinyl floating floors). ... For glue-down floors, adhesive-back tiles and nail-down floors, a ” plywood underlayment must be installed on top of DRIcore"


The makers of DriCore say it's ideal for use over concrete under engineered hardwood. Are they wrong? Also, a quick search for "floating engineered hardwood" yields lots of results. Doesn't this suggests that there are engineered hardwoods out there that can be installed as floating floors? I'm not trying to be combative, I'm just trying to understand what I'm working with.

Thanks!

JazMan 02-10-2009 09:17 PM

I don't doubt someone said they installed a CBU over a slab to raise the floor. You won't hear that from anyone who is a pro or from the manufacturers. You always spread thinset under, but you also have to fasten the panel.

If you think laminate won't hold up with a large dog, engineered hardwood is much worse. It'll scratch and be affected by any water spills if the water dish happens to be near it. Even drools after they drink will harm it. It'll probably look fine for 6-8 years though, unless it gets very little use.

To float the engineered wood make sure the subfloor is as flat as your kitchen table. Notice I said flat not level. You can add plywood over the DriCore and glue or nail the wood though.

If you can get the subfloor and DriCore to be in the same plane, you can get a nice installation and it will be warmer for sure. I can just picture a few hollow spots, or the DriCore warping after awhile. I also worry that in some basements it will hold moisture under the panels. And what happens to any spills?

Jaz


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