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Insulating Non-standard Size Spaces and Narrow Cavities

Home construction is fairly standardized, so insulating one room will usually be the same or similar as insulating any other room. JM insulation is manufactured in standard widths designed to fit the most common cavity sizes. However, it's likely you will encounter cavities that are nonstandard in size. In fact, up to 35% of cavities in newer homes are non-standard widths.

It's easy to ensure that you properly fill these nonstandard cavities with insulation. Follow the installation tips below and view the video for a demonstration.

Insulating Non-standard Size Spaces and Narrow Cavities

Installation Tips

During the installation process, you may encounter some cavities that are non-standard size, or are taller, shorter or narrower than the insulation batt. You will need to trim and piece the insulation.

Cut the insulation and facing 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.
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.
If it takes more than one batt to fill the height of a wall cavity, you need to make sure the two pieces are butted snugly together.

Another easy solution is to use Johns Manville's EasyFit® insulation batts, which have 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.

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