Installing Batt Insulation
Batts are pre-cut panels of insulation and are available in a variety of lengths, widths and R-values. Batt insulation is made to fit within most regular wall framing, which are usually spaced 12", 16", or 24" on center, and for either 8-ft. or 9-ft. high walls.
Batt insulation is available with and without facing. Faced batts are used in exterior walls as well as attics, finished basements, ceilings, floors, knee walls and cathedral ceilings. The facing material usually serves as a vapor retarder and makes handling and attachment easier to install. Factory-applied vapor retarder facings are generally made of kraft paper.
Faced batts are attached to framing members by stapling through the flanges. Unfaced batts are installed between framing members but not attached, allowing friction to hold them in place.
Installation Tips
In ceiling and attic spaces, use R-30 or R-38 batts.
In exterior walls R-13 to R-21 batts are usually used.
In interior walls where insulation is used for sound control R-11 is used.
To open packages cut lengthwise through the side panel. Be careful to avoid cutting the product or facing. Insulation will quickly expand to its full volume when the bag is opened.
Push the batt gently into the cavity so that it sits all the way in, especially check that the corners and edges are in. Then fluff it to its full expansion by pulling it forward to fill the depth of the cavity. It should fit snugly.
With batts that have facing on them, make sure the facing is toward the conditioned interior space, unless the building codes state differently.
Let friction hold the batts in place, or you can staple the flanges of faced batts to the inside or the face of the joists. Stapling on the inside is best because it is easier for drywallers and the drywall has a more even fit. Sometimes, however, the local building codes may require you to overlap the flanges and staple them to the edges of the framing members.
Be careful not to stretch the facing too tight as you staple. This can over-compress the batt and avoids gaps and puckers.
Secure floor insulation with wire fasteners (sometimes called "lightning rods"). Press the fasteners so they bow up gently against the subflooring without compressing it. Space them at least 6" from each end of the batt and 12" to 24" apart.
Cut insulation about an inch wider than the space using a sharp utility knife against a safe backstop, such as an unfinished floor or other smooth, flat surface. Always cut on the unfaced side of the batt. Sometimes batts have vertical perforations at intervals along the width of the batt so cutting is not needed. Simply grip the insulation on either side of the perforations and tear to trim it to the desired width.
If spaces are shorter, you will have to cut the insulation to fit properly. Never double it over or compress it because that will change the R-value of the insulation.
If it takes more than one batt to fill a cavity, be sure the two pieces are butted snugly together.
