How to Insulate Without Exterior Sheathing How to Insulate Without Exterior Sheathing

What You'll Need
Panel or roll type, faced batt insulation
Respirator
Polycarbonate safety glasses or goggles
Staple gun
Tape measure
Utility knife
Long sleeve shirt and pants
Work gloves

Homes without exterior sheathing can still be satisfactorily insulated. The most common insulation for this situation is batt insulation consisting of flexible fibers. Fiberglass batt is light weight but it's high density provides an excellent R-value. Standard ceiling height is 8 feet. Batt insulation comes in precut in standard widths, panels 8 feet long or in rolls which you can cut yourself. The facing on this type of insulation can provide vapor barriers and/or air barriers, certain types are also flame retardant. Without exterior sheathing, it is advisable to purchase insulation that provides all these barriers.

Step 1 - Measure

First measure floor to ceiling, then count the number of spaces between studs on the wall you will be insulating. For illustration purposes here use 8 feet for floor to ceiling measurement and 10 spaces. Multiply 8 feet x 10 spaces = 80 as your total lineage. Measure the distance between studs, this is the width of insulation you will need. Standard distances are 12 inches, 16 inches and 24 inches. Panel batt comes in a standard 8 foot long size. Rolls come in different lengths, so to determine how many rolls you need divide the total lineage by the length of the batt you chose.

Step 2 – Placement

Start at the top, gently place the non-face side of the insulation toward the exterior wall. Allow friction to hold it in place. Gently push on the insulation from the top down and side to side, taking care not to crush the batt as you go. Slightly pull the insulation back to where the facing is even with the front of the studs. Do not stretch the facing too tightly, this can over compress and cause gaps and puckers. Compression of the fibers removes air pockets and compromises the R-value of the insulation. Always trim any excess from the bottom. Do not fold or bend the excess to fit.

Step 3 - Fastening

Faced batt insulation will have small flanges on both sides of the panel or roll type insulation facing. The flanges or small excess piece of paper will allow you to staple it securely to the studs. Check local building codes to see if you can staple the flanges to the inside of the stud or if you are required to overlap on the face of the stud. Over lapping is highly recommended. This creates a better vapor barrier. A vapor barrier helps eliminate moisture from seeping to the interior walls. Dry wall installers prefer you staple to the inside, this gives them easy access to the framing studs.

Step 4 – Trimming

Panel type insulation will require minimal trimming. You will need to trim around any electrical outlets or windows. Roll type can be cut on a floor before installing or trimmed at the bottom with a utility knife after you have placed it on the wall. 

Additional Tips

Most panel and roll type batt insulation comes wrapped in plastic. When you open the casing take care, as it will expand when released. After you have finished your installation it is advised that you either discard the clothing you wore or wash them separately from any other clothing.

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