NC State Extension

Attic Penetrations – Types, How to Find Them, DIY Projects to Seal Them

Attic Air Sealing should be your first priority in air sealing. To better understand why the attic is a top priority, watch this video from 11:15 – 12:15.

Penetrations in the attic floor (plumbing penetrations etc.) soffits, ductwork and plumbing chases, attic accesses and pull-down stairs, recessed light fixtures, and wiring penetrations through the top plates of walls represent major connections between the attic and conditioned space. Many times unseen holes or pathways, called bypasses, occur at key junctures in the framing (such as at attic-to-kneewall transitions) and permit large quantities of air to leak in and out of the residence.

Anywhere two materials meet such as ducts, wires, and other penetrations in the attic. Look for “dirty” or brown insulation. Areas with air leaks often have dirty insulation around them because air is moving through the insulation as it escapes through the leak. The insulation acts as a filter and catches dirt in the air as it escapes through the hole / leak.

Refer to this useful factsheet for more information on sealing attic doors, hatches, etc.:

Written By

Photo of Laura LanghamLaura LanghamEnergy Conservation Program Manager (919) 515-8474 laura_langham@ncsu.eduAgricultural and Human Sciences - NC State University
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