GM-1001: Attic Air Sealing Guide and Details

Effective Date

This guide provides the background and approach for the prep work necessary prior to adding attic insulation - focusing on combustion safety, ventilation for indoor air quality, and attic ventilation for durability. The "Attic Air Sealing Details" section provides a scope of work and specification for the air sealing of many points of air leakage in common attic spaces.

The Guide to Attic Air Sealing provides information and specifications to the following groups:

  • Home remodelers

  • Builders

  • Insulation contractors

  • Mechanical contractors

  • General contractors who have previously done remodeling

  • Homeowners as a guide to the work that needs to be done

The order of work to be done during home improvements is important. Health and safety issues must be addressed first and are more important than durability issues. And durability issues are more important than saving energy.

Even though the purpose of this guide is to save energy – health, safety and durability should not be compromised by energy efficiency. Accordingly, combustion safety and ventilation for indoor air quality are addressed first. Durability and attic ventilation then follow. Finally, to maximize energy savings, air sealing is completed prior to insulating.

This guide is prescriptive-based to minimize risks. Enhanced performance and greater energy savings are possible with performance-based approaches. Performance-based approaches should build on the measures and specifications contained in this guide.

Not all techniques can apply to all houses. Special conditions will require special action. Some homeowners will wish to do more than the important but basic retrofit strategies outlined by this guide. Where possible throughout the manual, links have been made to “performance” path solutions that require the judgment and experience of design professionals and specialist skills and experience.

List of Attic Air Sealing Details


  • Attic Hatch, Access Panel
  • Pull Down Stair Opening


  • Balloon-framed Gable Wall
  • Common Wall
  • Dropped Soffits (bulkheads, arches, cabinet bonnets)
  • Exterior Top Plate at Soffit
  • Kneewalls
  • Top Plate Joints and Penetrations (Electrical/Plumbing)
  • Two Story Wall


  • Bath Fan
  • Chimney Chase – Masonry
  • Chimney Chase – Metal Pipe
  • Duct Boot
  • Electrical Box
  • Plumbing Stack
  • Recessed Can Ceiling Light
  • Rigid or Flex Duct and Chase