How to install a vapor barrier

If you’re constructing a wall, building an addition, or finishing your basement, installing a vapor barrier is a must. This thin layer of impermeable material, typically polyethylene sheeting, is designed to keep your home dry. Here are a few installation tips.

• Always install the vapor barrier on the inner side of the wall (the surface facing your living area) as it experiences hotter, moister conditions than the outside wall. A vapor barrier for the ceiling is also a must.

• Start in one corner and work your way around the room allowing the vapor barrier to hang down from the top framing sill. Once you’ve made it across the wall or around the room, allow for a fair amount of overlap in the corner where you started to create a tight seal.

• Make sure you seal cracks and holes in the wall. This will block any air gaps. Also, use acoustic spray foam or sealant tape to waterproof spaces around windows, doors, electrical outlets, and light fixtures.

Keep in mind that incorrectly installing a vapor barrier can lead to moisture problems and the need for costly repairs. For this reason, it may be best to leave this job to a professional.