Types of Roof Insulation
Roof Online Staff
About Roof Insulation
The following table lists the types of insulation that are used in low-slope roofing (or found in existing roofs).
These insulation materials usually take the form of 4’ x 4’ or 4’ x 8’ rigid boards. They are normally secured with adhesives or fastener systems, but they may be loose-laid in ballasted roof systems, which depend on the weight of the ballast to hold the entire system in place.
These types of insulation are used in above-deck insulation applications, which means that they are installed over the roof deck, and are considered a part of the roof system or roof assembly.
Steep-slope or pitched roof systems will almost never include insulation; in steep-slope construction, the insulation will be installed below the roof or above the ceiling.
|Types of Above-Deck Roof Insulation|
|Insulation Type||R-Value per Inch||Typical Colors||Notes|
|Cellular Glass||3.4||Charcoal, Gray||Also called “foam glass”. Extremely fire-resistant.|
|Fiberglass (Rigid Board)||4.3 – 4.5||Orange, Yellow||Also called “glass wool”. Commonly found in older built-up roofs. Not common today.|
|Gypsum Board||0.90 – 1.12||Gray, White||Used as a cover board or thermal barrier.|
|Lightweight Insulating Concrete||0.90 – 1.49||Gray||“LWIC”. Can be sloped and shaped during application. Much softer than structural concrete.|
|Mineral Wool||3.8||Gray, Tan, Yellow||Also called “mineral fiber”, “rock wool”, and “stone wool”. Very fire-resistant. Can have high recycled content.|
|Perlite Board||2.64||Brown, with whitish beads throughout||More fire-resistant than regular fiberboard. Often used as a cover board.|
|Phenolic Foam Board||6.7 – 7.5||Orange||NOT used in roofing any more. When it got wet it caused severe corrosion in steel roof decks. Many lawsuits resulted.|
|Polyisocyanurate||5.7||Yellow||Extremely popular in commercial roof installations due to ever-increasing energy code R-value requirements.|
|4.8||Yellow||Much harder than regular polyiso. Typically used as a cover board.|
|3.85 – 4.5||White||Also called “Styrofoam” or “beadboard”.|
|5.0 – 5.5||Blue, Green, Pink, White, Yellow||Very water-resistant. Common in green roof and protected membrane roof assemblies.|
|Polyurethane Foam, Closed Cell||4.9 – 7.1||Yellow, Orange||Spray Polyurethane Foam. Spray-applied. Considered a roof system in its own right. Requires a protective silicone coating.|
|Wood Fiberboard||2.5||Brown||Currently is typically used only as a cover board.|