# New plywood subfloor over concrete slab



## jeffaah (Apr 3, 2008)

OK....I have a job where the wants radiant heat in his basement. He is AGAINST laying the tubes and pouring more concrete over them. He is insistant on using the tubing tracks from Wisbro.

Wisbro's specs call for at least 5/8" ply subfloor glued and fastened directly to the concrete slab. Then the radiant panels are installed over the new ply subfloor

My question is......Is this a good technique? I have always layed sleepers and then ply. So while Wisbro's recommendation is not something I would normally do...is it still ok?

I would put a vapor barrier over the slab and shoot down 3/4" PT ply.

Jeff


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## neolitic (Apr 20, 2006)

jeffaah said:


> OK....I have a job where the wants radiant heat in his basement. He is AGAINST laying the tubes and pouring more concrete over them. He is insistant on using the tubing tracks from Wisbro.
> 
> Wisbro's specs call for at least 5/8" ply subfloor glued and fastened directly to the concrete slab. Then the radiant panels are installed over the new ply subfloor
> 
> ...


Test the slab to see if it has 
a vapor barrier.
Weight down a 3 or 4 foot square
of visqueen and leave it for at
least a few days. (week would be good)
If there is no condensate, you're good
to glue. :thumbsup:


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## Chris Johnson (Apr 19, 2007)

I prefer your sleeper route, go 24" o.c. and use 1 1/2" EPS to insulate below the tubes.


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## jeffaah (Apr 3, 2008)

Chris Johnson said:


> I prefer your sleeper route, go 24" o.c. and use 1 1/2" EPS to insulate below the tubes.


 
I agree and usually do the same thing... I normally still use 16" centers and foil faced ridgid foam.

Head room is a bit of an issue. If I can gain the 1-1/2" by not using sleepers, that would be better.


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## KennMacMoragh (Sep 16, 2008)

I have laid plywood right on a concrete floor before. But it was a small area in part of a room. I put 4 mil plastic and sill sealer under it, and it seemed to work just fine. What is the purpose of your sleepers? Is it just to insulate? Are you trying to straighten the floor? 

You might consider these too http://www.ovrx.com/basement-flooring.html 
It's a company in Canada that makes insulated floor tiles for a basement. You can order them at home depot by the pallet. Maybe you can install the tubes over that.


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## Cst Dsn Bldrs (Oct 17, 2008)

treated 1x4's as sleepers? 

If the plywood is made to be glued to the slab, i dont see a problem. Tell the customer that the floor will feel better and be better for his knee's if you float it.


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