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Types of insulation

Insulation does its job by creating small pockets of air that slow the transfer of heat through the insulation - in exactly the same way that a blanket works. Types of insulation vary according to use and location. Among the insulation options that work best in Minnesota's cold climate are the following:

Batts or blankets
Material Fiberglass, rock (mineral) wool.
R-value/inch 3.1 to 4.0
Method of installation Fitted between studs, joists and beams.
Where applicable

All unfinished walls, floors and ceilings.
Advantages Do-it-yourself. Suited for standard stud and joist spacing that is relatively free of obstructions.

Material Cellulose, fiberglass, rock (mineral) wool.
R-value/inch 2.4 to 4.0
Method of installation Blown into place (attics) or dense-packed (cellulose, walls).
Where applicable

Enclosed existing wall cavities or open new wall cavities. Unfinished attic floors and hard-to-reach places.
Advantages Commonly used for retrofits (adding insulation to existing finished areas). Good for irregularly shaped areas and around obstructions. Dense-pack cellulose in walls also provides an air barrier.

Rigid foam
Material Extruded polystyrene foam (XPS), expanded polystyrene foam (EPS or beadboard), polyurethane foam, and polyisocyanurate foam.
R-value/inch 3.5 to 7.5
Method of installation

Interior applications - must be covered with 1/2-inch gypsum board or other building-code approved material for fire safety.

Exterior applications - must be covered with weatherproof facing.

Where applicable

Basement rim joists, exterior walls under finish materials and vented low-slope roofs.
Advantages High insulating value for relatively little thickness. Can block thermal leak when installed continuously over frames or joists. Can provide both air barrier and vapor retarder.

Spray foam
Material Polyurethane, polyicynene.
R-value/inch 3.6 to 7.0
Method of installation Sprayed onto surfaces or behind a net facing.
Where applicable

Open wall cavities, between roof rafters.

Advantages High insulating value for relatively little thickness. Provides good air barrier. Some products provide vapor retarder.


Window rehabilitation - The most important energy-related function of a window is to prevent air leakage. Even aging windows can be repaired and tightened, improving energy efficiency and extending their life by many years. Windows that are difficult to repair (because of structural damage or challenges finding replacement parts) can be air-sealed easily and cheaply by applying shrink wrap film on the interior.