How to Hang Unfaced Insulation Batts on a Ceiling
- 1). Put on a long-sleeve shirt, dust mask and goggles or other protective eyewear. Climb the ladder and install the first batt of unfaced insulation. Because insulation is very light and fibrous, it will stay in the cavity without falling, if it is the proper width for the cavity. If it is too small, it won’t stay. If it is too large, the compression will cause a loss of R-value, a measure of the insulation’s properties to resist heat flow.
- 2). Tuck in one end of the insulation gently between the rafters, then continue tucking the length of the insulation across the cavity. Go back and tuck in the corners so the unfaced insulation takes on the appearance of a tucked-in fluffy bed. Ensure that no edges of the insulation stick out.
- 3). Smooth the face of the insulation once it is in place. Adjust it so that it is not compressed by running your gloved hand over the surface of the insulation. When insulation is compressed, it loses the air trapped between the fibers that give the insulation its R-value.
- 4). Install lighter batts first, if installing two batts into each cavity. Don’t shove the insulation in, and make sure that it fits snugly in place one over the other. Ceilings that require insulation of R-38 or higher may need more than one batt to meet this requirement. For instance, two R-19 unfaced batts installed one atop each other, without compression, have an R-value of R-38.
- 5). Add a polyethylene vapor barrier over the whole ceiling. This prevents a retarding factor to the movement of water vapor or moisture in the air. Attach the vapor barrier by unrolling it and stapling it in place against the roof rafters. Make sure that it's smooth, but don’t overstretch the material.
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