Reduce Moisture Risk with Properly Installed Vapor Barriers/Seal to Prevent Heat Loss

By Marvin Pirila

A successful energy plan begins with taking the right steps to eliminate heat loss and avoid moisture problems.  Every crack that allows heat to escape, as well as the vapor barrier that prevents moisture problems, affects the energy efficiency of your building.

Make sure you have sealed every gap around doors and windows.  Also, check for gaps where flues and wiring exit the house.  Caulking works well for smaller holes, while spray foam like Great Stuff is good for larger gaps. 

Attach vapor barriers, at least 6 Mil thick, to the warm side of walls.  This prevents moisture from entering and causing damage to walls.  Overlap the pieces of plastic with a generous amount and tape the seams.  Tape punctures to avoid moisture issues.  Remember to tape the plastic to electrical outlets, heat vents, and light fixtures.  If room permits in the space above your ceiling, seal any penetrations from the top.  Drywall screws may puncture a hole in the vapor barrier and require sealing.  Where the vapor barrier runs into existing framing there may also be gaps to seal.

Air is able to travel through small penetrations in framing for long distances.  This results in moisture related problems.  Seal any penetrations, such as those for wiring, to stop air movement.  Other penetrations may be due to construction methods, plumbing, and heating.  

Once you have sealed cracks/gaps/penetrations and the vapor barrier is in place, it’s time to insulate.