March 30, 2012

Attic Insulation

attic-insulationInsulating your attic is the most effective way to improve the efficiency of your home. Heating in the Winter time and cooling during the Summer time becomes easier for your heating/cooling system. I noticed on average a 30% to 40% reduction in the energy that my home used after installing attic insulation.

How Does Attic Insulation Work?

Heat flows naturally from warmer areas to cooler ones. It does this by one of three different methods: conduction, where heat is delivered directly from one mass to another; convection, the transfer of hot air from one space to another (hot air rises, cool air sinks); and radiation, which simply means that any warm mass passes off heat toward a cooler one.

The main function of insulation is to minimize the radiation and convection effect of heat and minimize conduction. This causes our home to stay warmer in cool weather and cooler in warm weather.

What is the Best Attic Insulation Type?

There are many different types of attic insulation, but the best type depends on your climate and needs. Two things that you will be looking for is the material used such as cellulose and the r value or “resistance to heat flow.” The more extreme the range of temperatures in your area the higher insulation r value you need. You can check your local energy commission, local power company, or local home center for the best R-value in your area or consult this map and chart courtesy of the EERE of the Department of Energy. Insulation R Value Map Insulation R Value Chart

Blown in Attic Insulation

Blown in insulation, as opposed to batt insulation which uses fiberglass blankets, creates a seamless blanket of insulation in your attic. You could spend hours kneeling to achieve the same result with fiberglass batts in your attic. Once installed and expanded to the uniform thickness, batts offer a known, consistent R-value. However, blown-in insulation thickness can vary in an attic space which leads to non-uniform R-values. Cellulose is a common and advantageous type of blown in insulation. One of the main advantages is its fire retardant characteristics.

If you decide to use blown-in insulation, place scrap lumber depth gauges throughout the attic. These pieces of wood can be marked to the desired thickness of insulation. Tack them to the ceiling joists in various locations and use them as guides for desired depth.