DIY Foam Core

Foam core is often added between plywood or waferboard structure and the exterior siding.

Foam core or foam board refers to a wide range of construction and building materials composed of an extruded lightweight plastic or polymer filling that has a foamy texture. Generally, these materials have high insulation properties and thermal resistance. Because of this, they are commonly used in renovations and in places where less-expensive fiberglass and cellulosic insulation are impractical. Foam core also can help reduce heat loss through structural materials, such as wall studs, in addition to fiberglass insulation. In either case, it's easy to install and can make a big difference in the energy efficiency of a home.

Things You'll Need

• Measuring tape
• Drywall square
• Utility or carpet knife
• Vapor-barrier nails
• Hammer
• Foil tape

Instructions

1. Measure the shape that the foam core will cover. In most instances, several full sheets will form the exterior wall with corners cut out to accommodate door and window openings. Transfer the measurements to a sheet on the ground by holding the drywall square against one edge of the foam board and drawing a marker or pencil along the square.

2. Hold the foam board against the structure's exterior to ensure the measurements are accurate. Redraw the lines according to Step 1, if necessary.

3. Return the foam board to the ground. Press the blade of the utility or carpet knife into the line marked by previous measurements. Slide the drywall square against the knife blade, and in line with the measurements, and pull the knife through the foam core, using the square as a guide for the blade. This will ensure consistently straight cuts.

4. Hold the foam board against the side of the structure where it will be installed. Press a vapor-barrier nail through the foam board then strike sharply with a hammer until the plastic washer is snug against the board. Continue pounding nails into the foam board at approximately 2-foot intervals.

5. Repeat Steps 1 through 5 to form a single row along the top just below the roof. Cut one board in half to start a new row in the middle of the top row. A staggered pattern should start to emerge as you go along. Continue measuring and cutting until the building's entire exterior is covered with foam board.

6. Seal seams in the foam core with foil tape and cover all nail holes with pieces of foil tape. This will increase the overall vapor-barrier properties of the structure.

References

• Energy Savers: Foam Board Insulation
• Hammer Zone: Installing Rigid Foam