What’s your insulation IQ?

Insulation is a primary ingredient in the formula for a comfortable home, but selecting the right type can be a confusing process. Here’s a short primer on some of the more common forms of insulation, and what it can do to help you.

R-value: An r-value is a measure of the thermal resistance of a product used in the construction industry. The higher the number, the more insulation the product provides.


Wall Insulation

Various types of insulation batting and boards. Some have a reflective/radiant (shiny) barrier, which is discussed in more detail farther down in this article.

Blanket insulation: This comes in rolls, or in sheets called “batts” that are made to fit between wall joists and attic rafters. It’s usually made of fiberglass, but is also made out of plastic fiber,  cotton, wool, and spun fibers of rock or slag. They can have a facing that acts as a vapor barrier. We’ve found that one rock wool product, made by Roxul, has an edge over fiberglass because over time, it retains its insulating properties better and is more water resistant. That’s in part because the fibers of the stone wool are non-directional, unlike fiberglass, and stone wool keeps its shape in places where fiberglass would get matted down. Matted material loses its insulation properties.


Foam board/rigid foam: A rigid panel of insulation. They can be used in the attic, on the sides of the house, and on the foundation. You often see them used on the exterior of a house before siding is applied.


Blown in Insulation

Loose-fill insulation being blown into an attic.

Loose fill/blown insulation: Small bits of cellulose, fiberglass, rock wool, or other materials, primarily made from recycled materials. The small particles conform to any space, making it an ideal choice for retrofits or use in locations where other insulation types would be difficult to install. If insulation is being blown into an existing structure, the contractor often drills holes in the exterior walls of the house, fills the walls with the blown insulation, and then plugs the holes. It can also be blown into attics and crawl spaces where batts would be difficult to install.


Reflective insulation/radiant barriers: As the name implies, these reflect heat, and work best in places such as attics, where the sun’s rays heat the roof and the heat, in turn, is transferred to the living space below. A radiant barrier reflects that heat away from the living space so that it’s not absorbed via conduction by other surfaces, such as the house’s framing or air conditioning ductwork. They must be installed in such a manner that they reflect the heat into an air space.


Fiber board insulation: These boards are made of mineral/rock wool or fiberglass. They’re mainly used to insulate heating/air conditioning ductwork, and are commonly custom-cut by contractors to fit the HVAC system.


Spray-foam insulation: Liquid foam can be poured, sprayed or injected. It’s great for filling odd shapes and small cavities where batts would be less effective. They can form a vapor and even a moisture barrier. There are two types, closed cell and open cell.

Spray foam roof

Spray-foam insulation being applied to the underside of a roof.

The cells in open-cell insulation are filled with air, because the cells, or bubbles, burst and air fills in the resulting gaps. That makes open-cell insulation soft.

 Closed-cell foam is rigid, and is often tough enough that it can be walked on without being compressed. The cells are filled with a special gas that increase the r-value of the insulation. Closed-cell foam is better able to resist air and water leakage, but it’s so dense that it takes a lot of the foam to fill a gap. This makes it more expensive. It’s an excellent choice, however, in places where it could come in contact with moisture — open-cell foam would absorb that moisture and the insulation would not only lose its effectiveness, but mold problems might result.


If you have any questions about insulation, don’t hesitate to send us an email or leave a comment below. And don’t forget that an energy audit is the best way to determine if your house could benefit from more or a different type of insulation. Contact us to schedule yours today!

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