Do You Need to Add a Vapor Barrier in Your Home?
Because common foundation materials, such as concrete blocks, are somewhat porous, adding an air or vapor barrier can be important an important step when it comes to insulating a basement, crawl space, garage or other unheated area of a house. To improve comfort and utility costs for adjacent heated rooms, home owners may consider adding insulation to the ceiling or walls of the unheated space. Another thing to consider is adding a vapor barrier.
A vapor barrier installed on the warm side of the insulation will prevent air from moving through the insulation, adding to the insulation’s effectiveness. A vapor barrier is difficult to install once insulation is already in place, so if you are planning to re-insulate an area of your home, you might want to consider also adding a vapor barrier.
It is important to avoid putting vapor barriers on the cold side of the insulation. This can trap moisture in the insulation, causing possible rot around wood framing or walls. Air and vapor barriers also should not be used to hold insulation to the ceiling of an unheated garage or crawl space.
An earthen floor in a crawl space or basement can cause elevated moisture levels in the air and promote rot in wooden structural beams, so it is advisable to add a moisture barrier like a polyethylene sheet over such floors. The moisture barrier should be sealed at the joints and around the perimeter. A layer of gravel or sand can help prevent rips or tears.
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