How do you cut rigid foam?

Foam board insulation is an affordable type of insulation board for a garage, work shed or any space that usually does not require interior finish or wall trim. To cut a rigid foam board insulation, prepare a tape measure, long straightedge, small rubber clamps, utility knife and crayon.

1. Measure the dimension

   Measure and mark the length of the foam board insulation that you want to cut. The mark serves as your cutting line.

2. Prepare to cut

   Line up a long straightedge with the cutting line. Clamp the tool to your insulation board, and ensure that the rubber clamps are placed securely so the pieces will not move while cutting.

3. Cut the board with a utility knife

   Run a utility knife along the outer edge of the straightedge to cut the insulation board. This creates a small etching on the board. Cut to the outside edge or "waste area," so that the board will not get damaged if you make a mistake. Set aside the straightedge and clamps after scoring the board.

4. Finish the cut

   Lift the insulation board to position the sheet upright. Press firmly on the backside of the etching line while holding the board's side edges. A properly scored foam insulation board should easily snap off through this process. Snap the board from its uncut side.