Iv’e been getting prices for foam panels to run aroung my slab and 2′ under it also. Is the “white” stuff any good. The manufacturer says its just as good with a r value of 4.0, not like the pink/blue’s 5.0. He says its poly styrene. Almost half the price of the pink/blue.
Any input appreciated.
-Brian
Learn how synthetic panels can create watertight shower walls and tub surrounds — or a big problem.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
I think the diffrence is that the white ends up soaking up moisture in this application, negating a considerable amount of its R value.
It is all poly strene.
The white, aka beadboard, is expanded. The others is extruded.
And the expanded can absorb mositure, but if you have a poly barrier that should not be a problem.
And if you any concerns about inspects (termites) then you can get the expanded made with borate. I don't think that is available in extruded.
migraine ... under slabs i would use borate treated EPS (white ).. i'd use the higher density 2.0 lb. /cf
i'd pay abut $ 0.50 /sf for that in a 2" thickness.. the 2" and the 2lb. is stronger and less susceptible to damage while pouring
some long term scandinavian studies show no absorption of water by EPS..that's what finally changed me over to EPS... that and the price.. and the borates
Mike Smith Rhode Island : Design / Build / Repair / Restore
I did a lot of research last fall on EPS last fall before building a 50'x50' airplane hangar, 6" slab with radiant heat. I came to the conclusion that EPS (white usually) and XPS (pink, green, blue, etc) are about the same from a practical point of view. The big companies probably like the extruded foam because it lends itself to a continuous process and is more efficient. But I think the EPS could be fundamentally less expensive to make. 6 mil poly under the foam eliminates the concern about water and PerformGuard treated EPS will help with bugs. I ended up using 2.5" R-10 1 lb/cu ft foam and had essentially no damage from the concrete work. There was a lot of traffic on the foam as we laid out the rebar and PEX tubing and damage was minimal. 1 lb/cu ft costs about 1/2 as much as 2 lb/cu ft. I used 4'x16' sheets; easy to handle and made for fewer joints than the standard 4x8 sheets. Branch River Plastics in RI was a pleasure to deal with.