For optimum energy efficiency,a well-insulated building must also be treated to eliminate air leaks in and out of the building. It is necessary to properly air seal the thermal envelope of each home. Air sealing is required in the latest International Energy Conservation Code and International Residential Code codes. (See Appendix.)The U.S. Department of Energy provides good information for air sealing new and existing homes on its website at www.energysavers.gov. The following information is from the 2006 IEEC,Section 402.4.1.
The building thermal envelope shall be durably sealed to limit infiltration. The sealing methods between dissimilar materials shall allow for differential expansion and contraction. The following shall be caulked, gasketed, weatherstripped or otherwise sealed with an air barrier material, suitable film or solid material:
1. All joints, seams and penetrations
2. Site-built windows, doors and skylights
3. Openings between window and door assemblies and their respective jambs and framing
4. Utility penetrations
5. Dropped ceilings or chases adjacent to the thermal envelope
6. Knee walls
7. Walls and ceilings separating a garage from conditioned spaces
8. Behind tubs and showers on exterior walls
9. Common walls between dwelling units
10. Attic access openings
11. Rim joists
12. Other sources of infiltration
A major area of air infiltration is the attic opening. Whether a simple"scuttle hole"or a more finished opening with a stairway or pull-down stairs, this opening should be thoroughly sealed and insulated. There are several insulated attic hatch covers that are excellent for this application. For more information on air sealing, visit the Air Sealers Institute of American at www.airsealers.com.