Case Studies

The Drying Co./ThermalTec Case Studies: Air Sealing & Insulating a Dunnsville, VA Attic

Tuesday, March 31st, 2020 by Erin Dougherty


This Dunnsville, VA homeowner reached out to us after seeing one of our crews working in their neighborhood. They had an older home with no insulation in the attic and were interested in their options for insulating their attic and making the home more comfortable.

The lack of insulation in the attic has been allowing heat to radiate down to the rooms below in the summer, warming them up and making these rooms difficult to cool. In winter months, when the attic is the same temperature as it is outside, the cold ceiling cools the warm rising air and causes it to fall in a process called Convective Looping. This makes the home feel drafty and makes it hard to warm these rooms.

Air leakage is a major contributor to high energy bills and uncomfortable rooms in a home. The can lights in the attic leak approximately 10 cubic feet per minute (CFM) of air, to put this in perspective, imagine 10 basketballs flying out of each can light every minute. That’s a lot of air loss! In addition to the can lights, air leaks out of top plates, electrical and plumbing penetrations, around the chimney, and the pull-down stair access. Per building code, chimneys must have a gap between them and any building material for fire safety. This creates a superhighway from the crawl space all the way to the top of the house for air to escape.

The attic is also home to HVAC equipment and ductwork. Ductwork in an unconditioned attic is essentially living outside. Therefore, when it is exposed to freezing winter temperatures, the cold duct lines cool down the warm, conditioned air you are trying to use to heat your home. The reverse is true in the summer as hot duct lines and sweltering attic temperatures warm up the air your HVAC system is cooling down. It creates a vicious cycle of uncomfortable rooms, high energy bills, and wear and tear on your HVAC system.



The homeowner chose to first air seal the attic at all top plates, utility penetrations, and install rock-wool can light covers. Rock-wool covers are fire retardant and sealed to the ceiling to prevent air leakage. To address the air leakage around the chimney, we sealed the gap with metal flashing, rock-wool, and fire-rated caulk. We then installed a dam around the pull-down stairs to prevent any insulation from falling down when the attic is accessed. Finally, we installed an R-38 of blown-in cellulose insulation. The Cellulose product used by The Drying Co. is 85% recycled material such as newspaper and 15% new material, it also contains a borate solution that deters pests.

Properly air sealing and insulating the attic will help reduce the energy bills, make the home more comfortable and reduce the wear and tear on the home’s HVAC equipment.

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The Drying Co./ThermalTec
236 Industrial Blvd
Suite A
Toano, VA 23168

The Drying Co./ThermalTec
Mailing Address
P.O. Box 637
Toano, VA 23168
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