Rigid insulation is generally purchased in 2’ x 8’ or 4’ x 8’ sheets, ranging in thickness from ½” to 2”, in ½” increments. The Expanded polystyrene (white, not pictured here) is similar to the old surfboards and commonly used in packing. Expanded polystyrene tends to be the most economical insulation per volume yet has a lower R-value then Extruded polystyrene (see below). Typical usage for the Expanded polystyrene is under poured slabs of concrete in a heated space.
Extruded polystyrene (blue or pink) has a higher R-value than the expanded, is more durable, and less porous.
Foil faced polyisocyanurate has the highest R-value per inch, reflects radiant energy, and is the most effective of these three rigid insulations In a recent renovation project we covered the entire existing roof with 1½” foil faced rigid polyisocyanurate, gaining greater efficiency in the home at a economical price (installed). Installation of rigid insulation with tapes and caulks makes an effective air-barrier that can be used during new construction or renovation.
These are just a few ways rigid insulation can be effective. We are consistently employing new proven practices with the many uses and locations rigid insulation can be utilized.
Insulation R-Values Per Inch
| Fiberglass batts or blown Denspack Cellulose Icynene (low density spray foam) Expanded Polystyrene (white) Extruded Polystyrene (blue/pink) Polyurethane (spray foam or board) Polyisocyanurate (spray foam or board) |
2.4 – 3.0 3.3 – 4.0 3.6 3.6 – 4.2 5.0 5.8 – 6.8 5.6 – 7.6 |