Can Metal Buildings Be Insulated?

Published January 24, 2014 by Whirlwind Team

metal building insulationCan metal buildings be insulated? The answer is an emphatic yes! In fact, you have several options for insulating a metal building which has a frame that is perfect for holding just about any type of insulation you choose. And considering the ability of metal buildings to soak in the heat in summer or let it all out in the winter, insulation really is a necessity for comfort and protection.

Metal buildings are especially susceptible to condensation which can result in mold or mildew. Insulation, as a vapor barrier, and proper ventilation can keep this from occurring.

There are a number of choices in insulation appropriate for metal buildings.


R-Value: R-3 per inch

Materials: Rock wool, fiberglass

Good for: Walls, floors, ceilings

Blanket insulation is one of the least expensive insulation options and can be highly effective for walls when installed properly. Blanket is laid between the building frame and the exterior roof or wall panels. Blanket can come with a radiant barrier on one side, adding a heat reflective property useful in hot, sunny environments.

Blanket is 2 to 6 inches thick. It comes in rolls up to 6 feet wide and can be as long as 120 feet long.

Rigid Board

R-Value: R-4 to R-8 per inch

Materials: Polyurethane, polystyrene, fiberglass

Good for: Flat roofs, basement walls, cathedral ceiling perimeters, concrete slab edges

Because it can be custom cut to a particular thickness, the R-value of rigid board insulation can be increased up to R-8 per inch. For interiors it must be covered by flame retardant materials such as ½ inch gypsum board. For exteriors you must use weather proof facing. In addition, local regulations may require added covering.

Sag and Bag (Faced Blanket Insulation Plus Loose Fill)

R-Value: R-3 to R-4 per inch

Materials: Cellulose fiber, rock wool, fiberglass

Good for: Walls, floors, attics

Loose fill alone is not generally used with metal buildings but with a method sometimes referred to as “sag and bag” it can be an option.

Loose fill is formed from pellets and loose fibers which are blown into a building cavity. In metal buildings a faced roll of insulation is draped loosely over the building frame. Loose fill or an un-faced blanket is then placed into the resulting cavity between the blanket and roof panel. Because fill is loose it can get into corners and irregular areas more thoroughly. This helps reduce air leakage and provides a sound barrier as well. Loose fill is slightly more expensive than other types of insulation.

While rock wool or fiberglass fill covers better, cellulose fiber from recycled and treated newspaper is an acceptable green option. Cellulose fibers also have a 30% higher insulating value than rock wool and fiberglass.

Of course, proper maintenance goes a long way towards keeping your metal building in tip-top shape. If you did not originally insulate your building, you can add it later if you open the walls or roof/ceiling for repair. It is a good investment that pays for itself in lower utility bills and longer lasting metal.

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