We are rehabbing a condo with a slab floor.  I would like to seal the floor and add either a radiant barrier and / or insulation prior to putting down the finished floor (engineered click-together bamboo).  I do not want to add a great deal thickness to the floor as I will then ahve to undercut allth edoors, molding, etc and the transitions between entryway thresholds and the floor may become tricky.

Any suggestions on products for sealing, radiant barrier, or insulation - ?

Thanks.  Mitch

You will get the most insulation per inch out of polyiso board foam. Is this "click together" bamboo floor a floating floor (like laminate floor)? If so, you could always put down a continuous layer of polyiso foam, whatever thickness you want, then install the floating floor over it. For example, you could put down a continuous layer of 1/2" polyiso foam, then the floor pad, then the floating floor material, netting you an extra R-3 to R-4. You could put in an inch to get an R-7 to R-8. The only trick will be that you have to be careful about walking on it until the floor is installed. Once the floor is down, it will spread out the weight, and won't bother the foam, but if you are rough on the bare foam, you could crush it in places.

If it isn't a floating floor, there isn't going to be a "thin" solution. In my next house, in the basement, we want to have nail down solid hardwood. We are going to install 4" of polyiso foam, then two layers of advantech plywood screwed together, "floating" in each room, to give us a good base to attach to. Then, we will nail down our hardwood.

Thanks Ardvarcus! We got a small Radon result (0.6 picoCuries / liter) coming off the slab (the test was done on top of the existing carpet - The federal action level is 4 picoCuries / liter) I was thinking of patching any cracks in the slab and sealing prior to putting down any insulation - Good idea?? Or Overkill??

Posted By Mitch K on 17 Feb 2010 10:20 AM
Thanks Ardvarcus! We got a small Radon result (0.6 picoCuries / liter) coming off the slab (the test was done on top of the existing carpet - The federal action level is 4 picoCuries / liter) I was thinking of patching any cracks in the slab and sealing prior to putting down any insulation - Good idea?? Or Overkill??

Overkill.

Random sampling of OUTDOOR air across the US averages around 0.4pCi/l- that 0.6 reading could easily have been the same as your outdoor air during the test period, in which case no amount of sealing or ventilation would touch it.  Remediation to levels below 2.0pCi/l is generally pretty difficult if you have a real radon source below you (like a mile thick slab o' granite or something.)  If you're already under 1.0, fuggedaboudit.