How to Install Insulation Sheathing

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Insulation sheathing provides insulation for those areas that allow heat and cold to escape your home. Electrical sockets are the most well-known areas where this occurs. Studs also provide access for heat and cold to escape, this is called thermal bridging. Extruded polystyrene or polyisocyanurate are two of the most common types of foam board insulation sheathing materials available. Polyisocyanurate has a higher R-value than polystyrene. R-value is the rating given to the amount of heat flow resistance an insulation sheathing carries. Check local building codes for local R-value standard requirements. Insulation also provides noise control and air infiltration. With the right tools and materials installing insulation sheathing can be accomplished in a relatively short period of time. Successful installation begins with the preparation of your tools and materials.

Choosing the Insulation

The type of insulation sheathing panels you choose has a great deal to do with what type of walls and/or the siding you are applying. Generally, it is advisable to use panels with either reflective aluminum or matte facings underneath brick, stucco, and certain wood sidings. Use Non-foil-faced panels beneath an aluminum, vinyl, and wood-based siding. The standard insulation sheathing panel sizes are 2 by 8 feet, 4 by 8 feet, and 4 by 9 feet, The foam board thicknesses range from 3/8 inch to 4 1/4 inches. Larger panels can be 50 feet long and fold in an accordion style. The accordion folding of the sheathing makes handling the panel easier.

Preparing Materials

Most insulation sheathing panels are extremely lightweight and capable of being cut with a utility knife. If you need to cut a panel use the 2 by 4-inch board as a straight line guide. Do not precut any panel. Cut each panel individually for each section. In the event you accidentally cut or score a panel with a nick 6 inches or longer, repair it with duct tape. Leaving these nicks open can cause the sheathing to weaken in that area.

Sheathing Placement

The facing of the sheathing should be placed toward the living space. Align each panel of insulation as close as possible to the previous panel.


Use either staples or nails recommended by the manufacturer. Most insulation sheathing is stamped with the manufacturer’s instruction providing the suggested type of fasteners to be used, along with the distance used between fasteners. In most cases, sheathing panels should be stapled approximately every 8 to 12 inches, or according to the manufacturer’s instructions. The insulation must be properly stapled or nailed over the face of the studs; it must be overlapped with no gaps to ensure the best seal. When using nails make sure you drive the nail flush without crushing the panel.