Foam Insulation comes in two main forms. It’s either installed as rigid board (beadboard), or a spray foam insulation.
It’s significant to note that if your only concern is R-Value, not ease of installation, cost or environmental factors, rigid foam insulation is the clear winner. It has a higher R-Value per inch than either batts/blankets and loose fill insulation. Nearly twice as much, as a matter of fact.
There are three types of rigid foam. Expanded Polystyrene (EPS), Extruded Polystyrene (XPS) and polyisocyanurate. From a purely environmental standpoint, EPS is the best choice because it isn’t manufactured with chemicals, and is a closed cell insulation.
XPS is also a closed cell insulation, however it’s more expensive, and it contains hydro chlorofluorocarbon (HCFC)—which breaks down and can impact the ozone. HCFCs are to phased out by the year 2030.
However, again, if your only concern is R-Value, XPS does have a higher R-Value than EPS. It’s also stronger than EPS and does a better job at keeping moisture at bay.
Of the three types, polyisocyanurate is the least environmentally friendly but has the highest R-Value.
And what about spray foam? Today’s spray foam isn’t not your cancer causing, urea formaldehyde foam, of the 70’s. It contains a polymer and a foaming agent. It’s sprayed into cavities via a hose and a small hole. It starts expanding on contact—expanding to almost 100 times—into a solid, cellular plastic material.
As far as initial costs go, spray foam is more expansive than using batt insulation, but buying a kit and doing the job yourself, will cut down on your costs. And if you take into consideration all of the other associated costs with batt insulation, such as a vapor barrier and so forth, things might even out in the end.
