Myths and Reality on how Insulation Keeps Your Home Warm (or Cool)

As with a lot of areas in the HVAC world, many clients we see for Cincinnati furnace and AC maintenance and repairs seem to be misinformed about insulation and how it works to save energy and improve comfort in homes. When you learn the truth about insulation, you’ll be better equipped to use it correctly. Following are some popular myths about insulation, along with the truth.

Myth: Some insulation does a good job of blocking airflow as well as the transfer of heat energy.

Truth: Yes, while some types of insulation are more effective than others at keeping air from escaping or entering your home, no insulation can be expected to do the job of proper air sealing.

Areas of the home where building materials connect, such as sill plates and window frames, should be tightly sealed with spray foam, caulk or weatherstripping. The same goes for any spot where wiring, pipes, vents or cables penetrate the outer envelope of the home.

These are common places where you’ll find air moving into and out of the home (as well as insects and other critters).

Myth: Insulation’s main utility is blocking air infiltration through walls or roofing.

Truth: Insulation’s primary job is to stop heat energy, not air, from transferring between the outside of the home and the inside, through

• walls,
• floors,
• ceilings,
• roofing,
• foundations,
• ductwork, etc.

In the winter, insulation retains heat inside, giving your heating system an easier job keeping your home comfortable for a longer period. In the summer, insulation holds off heat transfer from outside. Insulation is rated by its R-Value, a metric that shows a given type of insulation’s effectiveness at resisting the transfer of thermal energy.

Myth: Spray foam is a good way to seal a wall cavity; it will do the job of traditional air sealing methods such as caulk and other sealing agents.

Truth: Yes, you can apply spray foam insulation to prevent some local movement of air. However, it shouldn’t be used throughout the house for this purpose.

Air infiltration/escape can occur throughout the house, not just in wall cavities. Effective air sealing is necessary at sill plates, gaps where utility and venting penetrate the home, recessed lighting and circuit boxes, and windows and doors. While spray foam insulation can help stop airflow, it’s not designed to work as a continuous barrier against air infiltration.

Myth: All insulation is basically the same. The more you use, the better off you are.

Truth: Actually, insulation varies greatly, both in its thermal resistance/R-factor and its type and application. An experienced Jansen Heating & Cooling technician can counsel you on what type of insulation is right for different uses in your home, whether it’s in the attic, wall cavities, around ductwork, or other areas.