Do air-sealing and insulation in your house yourself!

Do air-sealing and insulation in your house yourself!

The following you can do only if found to be cost effective as determined by sequential blower-door-guided air sealing.

• Cracks in exterior window and door frames should be sealed. If the crack is deeper than 5/16-inch, it must be backed with a material such as flexible polyurethane, neoprene butyl rod, fiberglass, or sponge rubber specifically manufactured for this purpose and then sealing it with caulk.  Remove any existing loose or brittle material before re-caulking. Caulking should be applied in a manner that is sealing the area thoroughly and is neat in appearance.

• Joints in sill plate (mud sill) and around utility openings in siding and foundation should be sealed in an appropriate manner. When there is a space between two metal surfaces it needs to be sealed, using only a butyl or silicone caulk is the best solution. Cracks between two masonry surfaces should be sealed with a cement patching compound or mortar mix. If the opening is deeper than 3/8 inch, follow procedures described above.

• Interior joints should be caulked. These joints include where baseboard, crown molding and/or casing meet the wall/ceiling/floor surfaces. Gaps around mounted or recessed light fixtures and ventilation fans shall be caulked, too.

• Insulation gaskets are useful in trying to attain a tight interior air barrier, but not cost effective in every case.

Air-Sealing and Air-Leakage


These specifications address energy-efficiency measures are designed to improve the building’s thermal boundary. Performing an air leakage testing and evaluation before beginning air-sealing or insulation work is recommended. Also, use a visual inspection to determine the cost-effectiveness of adding insulating value to a building by installing insulation or window treatments. Reducing air leakage and adding insulation use the same general approach. The most needy areas are retro-fitted first and then less needy areas are retrofitted as time and budget permit.


Why do I need to reduce air leakage through air-sealing?

Air leakage in homes represents from 5% to 40% of annual heating costs. Air-leakage reduction is one of weatherization’s most important functions, and often the most difficult function.

The four main functions of air-leakage reduction are to:

1. Saving energy
2. Increasing comfort
3. Protecting insulation’s thermal resistance
4. Avoiding moisture migration into building cavities

Air leaks into and out of the building happening by three main ways:

1. Bypasses, which are significant flaws in the home’s air barrier.
2. Seams between building materials.
3. The building materials themselves.

The ultimate goal of air leakage reduction is to establish an effective air barrier. Before air sealing, be aware of all air-pollution and house-pressure hazards. State and local governments may set standards for air-tightness levels and ventilation.


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