Insulation and Air Sealing Explained

Winter is here! Temperatures hit record lows with the arrival of the polar vortex in North Carolina in January, and along with with it the realization by many homeowners that they are battling drafty rooms, cold floors, and heating costs that rise into the hundreds of dollars each month. But these extreme conditions only serve to emphasize energy efficiency problems that, in reality, are present all the time.

The ability of a house to keep its occupants comfortable depends on the performance of its thermal envelope and airtightness, that is, the blanket of insulation and the air barrier in its ceilings, floors and walls. Whether keeping heat out during the summer or keeping it in during the winter, proper insulation and air sealing can help minimize utility costs while improving the overall comfort inside the home. Improving substandard insulation and sealing up air leaks are the two most recommended items that arise from an Energy Audit, and homeowners commonly report a terrific return in lower utilities and greater comfort on a very modest investment.

With so many types of insulation now available, including fiberglass batts, loose-fill cellulose and fiberglass, and different types of spray foam, how does the average homeowner know which product and installation method is right for them? And what should a homeowner know about air sealing a home? Below is a quick breakdown of the primary information a homeowner should have:

Replacing or Enhancing Old Batt or Loose-Fill Insulation With New Materials

The existing insulation in many homes dates to the home’s construction and probably includes batts (i.e. strips with or without paper facing) of old fiberglass or wool or blown-in versions of the same. Often unsubstantial in the first place (or even nonexistent!) these materials tend to get compressed, torn out by people and animals, compromised by dust and moisture and otherwise rendered insufficient as a thermal blanket – and sometimes even dangerous to indoor air quality. Replacing or enhancing old, compressed or low R-value insulation in your home is the baseline option you should take to improve your home. Homeowners tend to be most familiar with fiberglass batt insulation, but blown-in, loose fill versions of eco-friendly fiberglass and recycled cellulose have become increasingly popular in attics in recent years.

Easily accessible areas like unfinished attics and the subfloor in the crawl space are the most logical and cost-effective locations to improve a home’s thermal envelope with added insulation. If the existing insulation is in place, a home energy professional can evaluate whether its condition warrants removal or if it just needs to be increased and improved. In either case, the primary goal is to establish a high R-Value which will slow down the loss of heat in the winter and the gain of outdoor heat in the summer, thereby making your HVAC system work less and keeping the inside of the house more comfortable.

Improving Your Home’s Air Barrier

Insulation slows down heat loss and heat gain through the building envelope much like a thermos helps to keep a beverage at its desired temperature for a longer period of time. But even well-insulated homes may exhibit poor energy performance if leaks air between the conditioned interior and the harsh exterior. The most common locations for air leaks are where electrical wires, plumbing pipes and other utilities like duct boots pierce the home’s primary air barrier. Places where different building components meet, like drywall to framing connections, also allow air exchange between the inside and outside of the home. Improved air sealing is accomplished by filling all of these gaps with precisely applied expandable spray foam. In addition to improving the energy efficiency of the home, air sealing also reduces the flow of air from undesirable locations, like attics and crawl spaces, into the breathing environment of the interior.

Spray Foam Insulation

While fiberglass batts and loose-fill materials represent economical approaches to achieving a respectable R-Value, an even better option is spray foam insulation – a truly exceptional product in both old and new homes. Spray foam not only offers all the benefits of creating high thermal resistance in a building’s envelope, but it also serves the added purpose of air sealing all the cracks and holes in a home’s air barrier where leaks lead to costly and uncomfortable air infiltration. Additionally, it expands to fill hidden corners and hard-to-reach angles where batt and loose-fill insulation may not be an option. Furthermore, spray foam insulation also provides excellent soundproofing, making a home not only more efficient and comfortable but quieter as well.

While the extremes of winter are the most common times for homeowners to show an interest in improving a home’s thermal envelope and airtightness, it’s important to remember that better insulation and lower infiltration have year-round benefits. If your heating or cooling bills seem high, or if you’re just tired of being uncomfortable in certain rooms of your home, improved insulation and a tighter home are terrific first steps in achieving the efficient, comfortable home you deserve.