Density of polyiso compared to XPS?
whitenack
| Posted in Green Products and Materials on
A local supply house is running a good discount on Polyiso. My builder is familiar with XPS, but not polyiso, and is asking me about the density. How does it compare?
I think the trouble is that he has been bitten by crumbly EPS in the past and doesn’t want to go down that road again.
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Replies
Clay,
The density of polyiso typically ranges from 2.0 to 2.5 pounds per cubic foot.
The density of XPS ranges from 1.5 to 2.8 pounds per cubic foot.
Roofing iso is typically ~2-2.5lbs, density with a higher pounds per square inch resistance to make it "walkable" when covered by a membrane roof. I think there are a few lower density lower psi wall sheathing products out there, but can't point you to a specification without some web-searching.
Polyiso (at any density) doesn't have the macroscopic bead structure that makes low-density EPS so fragile. The facers add some ruggedness against denting, but are primarily there to lower the vapor permeance.