How to: Polystyrene Insulation Sheets

Polystyrene insulation sheets and boards are actually made of groups of small bubbles or beads, filled with polystyrene foam and then encased in a surrounding sheeting to hold them in place. Similar to Styrofoam, these beaded pieces are generally go on the exterior of the walls of the home before the roofing material or siding go into place; if there is existing siding on the walls, the insulation can go over the existing pieces and then be covered with new siding. The insulation sheets keep the air inside safe from changing temperatures and raging climate of the outdoors, cutting down on power bills.

Things You'll Need

• Stud finder
• Chalk line
• Level
• 3/8-inch diameter galvanized roofing nails
• Hammer or nail gun
• Utility knife

Instructions

1. Locate the studs of the wall with a studfinder and mark their locations on the wall with a chalk line. Mark both edges of each stud and then run a chalk line right up the middle; the fasteners hold best if installed as close to the center of the stud as possible.

2. Hold your first insulation sheet up against the wall and line it up so that it is flush with one corner. Use a level to make sure the sheet is completely flat against the wall with no gaps.

3. Secure the sheet in place with 3/8-nch diameter galvanized roofing nails, installed with a hammer or nail gun. Set a nail every 24 inches along each stud that the insulation sheets cross to hold it firmly in place.

4. Butt the next piece of siding firmly against the first and continue to install all along the wall. When you come to a corner or obstruction, mark the line along which the sheets need to be cut, with chalk or a pencil. Score the sheets along the cut line with a sharp utility knife and then snap the sheets along the scored lines to get them to size.

5. Sand any rough cut edges lightly with a rasp or fine grit sandpaper to make the edges completely smooth. Otherwise you may have small gaps between the sheets of insulation.

6. Continue to cut and nail all polystyrene sheets until the installation is firmly in place.

Tips & Warnings

• Read all product instructions and warnings that come with your polystyrene insulation sheets. These will provide any manufacturer-specific recommendations or requirements for fasteners and cutting the sheets.

• Use only galvanized nails; these are rust-resistant. The nails must penetrate at least ¾ inch into the wall of your home for proper holding.

References

• United States Department of Energy: Foam Board Insulation
• Dow Building Solutions: Existing Walls---Installing Styrofoam Residing Board, Residential Sheathing, Tongue and Groove, Duramate Plus, Tuff-R, Super Tuff-R