As the seasons change, cracks and gaps will open and close and allow unwanted air to infiltrate, conditioned air to pass and moisture to leak into the home. This can cause a number of problems such as mold, drafts, and heat loss in the winter or gain in the summer.

Leaks can be sealed with caulk, spray foam or even just weather stripping depending on the problem area. A good rule of thumb is to use caulk for cracks smaller than 1/4-inch, and foam for larger cracks and gaps, though each condition may vary. We’d recommend checking these areas in your home:

Exterior

  • Windows & Doors: Insulate around frame with a low expanding foam insulation, caulk at frame & drywall/trim intersection, consider adding storm windows to single pane units.
  • Wall Penetrations (pipes, vents, exhausts, air intakes, etc): Caulk around the perimeter of all exterior wall penetrations.
  • Trim: Caulk around the perimeter of trim, and trim/siding intersections.

Interior

  • Windows & Doors: Caulk at frame & drywall/trim intersection, install weather stripping if needed, and add insulation and/or gaskets/weather stripping to attic access panels.
  • Tubs & Showers: Caulk at shower/tub and wall intersection and around plumbing fixture perimeter.
  • Outlets & Switches: Foam around perimeter of electrical box with low expanding foam, and install gaskets behind electrical plates.
  • Lights: Caulk around light trim and use housing/cans that are labeled as insulated airtight fixtures.
  • Trim: Caulk around trim.
  • Pipes & Ductwork: Caulk any wall penetrations, wrap hot and cold water pipes with insulation, tape all duct joints and seams, and insulate ducts in any unconditioned spaces.
  • Fireplaces: Keep damper closed (or install inflatable chimney balloon) when fireplace isn’t being used, consider adding glass gasketed doors to fireplace opening when appropriate.
  • Basements & Crawlspaces: Caulk or foam at the foundation wall & rim joist intersection and seal any cracks or joints in the foundation walls.

more @ http://www.re-nest.com/re-nest/green-architect/the-importance-of-air-sealing-green-architect-113290