Darrin Saffell, Olympic Restoration Systems

Attic Air Sealing / Insulation

About the Expert

Olympic Restoration Systems helps customers achieve healthier, more comfortable homes by providing a range of services, including attic insulation, air sealing, mold removal, and crawl space repairs. The company is fully licensed and insured and has an A+ rating with the BBB. Olympic Restoration Systems can help with problems big or small and provides free estimates on all services.


My AC company says my system is working properly, but the air coming out some of the vents isn’t that cool. How can this be?

Temperatures can reach 160 degrees Fahrenheit in our attics during the summer. AC ducts are typically in the attic. The AC cools the air down as it passes through to about 55 degrees. The cool air is in the duct, and the only thing separating the hot air from the cool air is a bit of insulation.

If you have a long duct run, air can easily be heated 10 to 20 degrees. So, your AC system could be working fine, but the cool air is getting reheated before it makes it into your house. The best way to protect against this issue is to encapsulate the ducts with spray foam insulation.

How much insulation do I need in my attic?

Insulation is measured in R-values. R is resistance to heat flow. R-30 is the code minimum for North Texas, but ideally it should be at R-60, which is the maximum. We want to prevent the heat from the attic from coming into our homes. A thicker layer of insulation can help keep the hot air separated from the cool air in the house.

Does it matter what kind of insulation I use?

Fiberglass is common in our area, but we prefer cellulose because it is denser. To get the same R-value, you need 16.5 inches of cellulose versus 22 inches of fiberglass. As the heat in the attic tries to pass to the house, the cellulose insulation does a better job of resisting the heat flow.

At 110 degrees Fahrenheit, the cellulose insulation has a 97% efficiency while the fiberglass insulation only has an 89% efficiency. Cellulose includes a mineral called borate which acts as a fire retardant and helps deter rodents and pests.

I have heard of air sealing, but I don’t really understand what it means or why it is necessary.

Air sealing is a process in which all pipe and wire penetrations going into the attic get sealed, the gap between the drywall and the top-plates gets sealed, and things like lights and ceiling fans get sealed in a way where air cannot pass from the house into the attic. The work of air sealing helps reduce the stack effect and allows you to keep more of the air you have already cooled or heated in your home.

Is there ever a need to remove the existing insulation and start over with new insulation?

Yes. One reason would be if you wanted to air seal, but also it is good to remove the insulation if rodents have ever been in the attic. This allows all the contaminants to be removed and the remaining building materials to be sanitized. Also, dust, allergens, and irritants can build up in the insulation in your attic. Vacuuming out all the old insulation and debris helps make the space much healthier. 

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