Vapor Barrier Installation
As much as I am not a huge advocate for using minimum code fiberglass insulation, it can be effective in wall cavities as long as the material is applied properly and the vapor barriers are installed diligently to prevent air infiltration into the home. Here are a few simple tips for installing vapor barriers.
Overlap
As a general rule of thumb, it is important to overlap the seams of vapor barriers at least six inches. However, to make sure that there is no way air can move through the vapor barrier, twelve inches is preferred as this large of an overlap will significantly reduce any chance of air infiltration.
House Wrap Tape
Do not be afraid to tape vapor barrier joints. If there are any joints that you feel may not fully prevent air infiltration, they should be taped to prevent air infiltration.
Seal to the Floor
Sealing the vapor barrier at the ceiling is required by code. Sealing the vapor barrier at the floor is equally as important as many drafts can come from the bottom framing plate when the wood shrinks. As seen below, it is very simple to caulk the seam of the framing and push the vapor barrier into the seam using a square. Then staple the excess down to the floor to prevent the vapor barrier from being pulled away.
Pull Tight
It is important to keep the vapor barrier as tight as possible when stapling it to he framing. This prevents air pockets and will help keep any air movement from going under insulated surfaces.
Don't Bunch up Corners
Bunching up the corners of the vapor barrier will cause issues when drywalling and the drywallers will cut the corners negating the effectiveness of the vapor barrier. By slitting the corners enough so that you can fold them and staple them to the framing cleanly, the vapor barrier will stay intact and the drywallers will not curse you throughout the job.
Installing the vapor barrier properly is one of the most important aspects of insulating properly. It will save you money, save your drywall installation crew time, and prevent moisture issues from forming as the years go by.
