While most people don’t give much thought to what’s in their attic or behind their walls, proper insulation is key when it comes to having a comfortable home, lowering energy usage, and preventing moisture problems.
The Role of Insulation
There are three types of heat flow mechanisms: conduction, convection, and radiation. Conduction is the way heat travels through materials. Convection is the way heat circulates in liquid and gases. And radiation travels in a straight line and heats anything solid in its path.
According to the Department of Energy (energy.gov), heat flows from warmer to cooler until there is no longer a temperature difference, regardless of the mechanism. So in the summer, it keeps the warm air outside, and in the winter, it keeps the warm air inside. It does this by trapping pockets of air which slows down the heat flow process.
How It’s Rated
Insulation is rated by the measurement of resistance the material has to heat transfer, also known as R-value. The higher the R-value the more effective the insulation is. The installation greatly affects the R-value of the material. If installed poorly, this can cut the value substantially. For example, you can install R-30 fiberglass batts but if the batts are not installed perfectly flush with the attic floor, it can cut down to less than half. The reason is because there are gaps between the insulation and the attic floor, which can cause convection heat in those gaps. That heat then turns into radiation heat from the attic floor to inside the home. For more information about R-Value, visit us here.
Types of Insulation
There are a few types of insulation to choose from but there are three common types that are used today: cellulose, fiberglass, and spray foam.
Cellulose: Being a loose-filled material, it is mostly used in attics as it fills in irregular holes and gaps. It is a dense material so it does act as a good air sealant. And with it being made from recycled material, there are obvious environmental benefits.
Fiberglass: This is what people commonly refer to as “the pink stuff” but it also comes in the color white. Fiberglass comes in batts (rolled) and loose-filled. The batts are typically used in exterior walls and the loose-filled are used in the attic.
Spray foam: Spray foam is an excellent insulator and air sealant. It comes in two different ways: closed-cell and open-cell. Closed cell foam is typically used in crawlspaces or attics as air and water does not travel through the material. This is a great option as it prevents moisture problems such as mold or mildew. Although it does act as a better air sealant than open-cell, you do want your home to “breath” due to the repellents, exhaust from cooking, etc. Open-cell is typically used in exterior walls so that the home does have this “breathing” factor but adds a substantial amount of insulation.
Closed-cell spray foam can be used on exterior walls as long as a proper HVAC system is in place to ensure adequate ventilation.