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How to Install 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. (JM's EasyFit® insulation batts feature vertical perforations that allow you to easily tear the insulation by hand for fitting into non-standard-width cavities.)

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.

Batt Insulation Tips

  1. For ceiling and attic spaces, use batts of R-30 or R-38. In exterior walls R-13 to R-21 is commonly used, while in interior walls where insulation is used for sound control, R-11 is used most frequently.
  2. Open the packages by cutting lengthwise through the side panel. Be careful to avoid cutting the product or facing. Insulation is compression packaged. Handling or fluffing the product during installation helps the product expand to full thickness and delivers the highest R-value.
  3. Gently push batts into the cavity so that it sits all the way in, especially at the corner and edges. Then, fluff it to its full expansion by pulling it forward to fill the depth of the cavity. The fit should be snug,
  4. With faced batts make sure the vapor retarder is facing the conditioned interior space, unless building codes specify otherwise.
  5. Allow friction to hold the batts in place. Or you can staple the flanges of faced batts to the inside or face of the joists. (Stapling on the inside is preferred by many drywallers because it leaves the edges of the framing members easier to locate. However, your local building codes may require you to overlap the flanges and staple them to the edges of the framing members.)
  6. Take care not to stretch the facing too tight as you staple, which can over compress the batt, and avoid gaps and puckers.
  7. 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 the fasteners at least six inches from each end of the batt and 12" - 24" apart.
  8. 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.
  9. Johns Manville's EasyFit® batts have vertical perforations at intervals along the width of the batt so cutting with a knife is not needed. Simply grip the insulation on either side of the perforations and tear to trim it to the desired width.
  10. For shorter spaces, cut the insulation to fit properly. Don't double it over or compress it. Compression changes the R-value of the insulation.
  11. If it takes more than one batt to fill the height of a wall cavity, make sure the two pieces are butted snugly together.

Related Products

ComfortTherm® Batts and Rolls


ComfortTherm® insulation is a lightweight, thermal and acoustical insulation made of long, resilient glass fibers bonded with an acrylic thermosetting Formaldehyde-free™ binder.

EasyFit® Batt Insulation


JM's EasyFit® Formaldehyde-free™ insulation is available unfaced or with kraft facing, and has vertical perforations for fitting non-standard wall cavities.

Kraft-Faced Batts and Rolls


JM's Kraft-Faced Batts & Rolls are made of naturally white, Formaldehyde-free™ fiber glass, reducing environmental concerns including the risks of poor indoor air quality and the effects of manufacturing on the environment.

Unfaced Batts and Rolls


JM's Unfaced Insulation is a lightweight thermal and acoustical fiber glass insulation made of long, resilient glass fibers bonded with an acrylic thermosetting resin made without formaldehyde.

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