Cutting Rigid Foam Board Insulation

Foam board Insulation is a relatively inexpensive type of insulation board that adds a high R-Value to areas where adding standard installation is either cost-prohibitive or not required. Foam board insulation is often used in garages, work sheds or other spaces that may not require interior finish or wall trim.

While formed foam board insulation offers a quick solution to your insulation needs, it is very messy and difficult to work with—especially when you're trying to cut it. Follow these steps for an easier project.

Step One - Measuring

Measure the distance on the foam board insulation that you wish to cut, and then make a mark there. This will serve as your cutting line.

Step Two - Preparing to Cut

Take your long straightedge and line it up with your cutting lines. Clamp the straightedge to the foam insulation board. Make sure your rubber clamps are securely and firmly in place so that the pieces will not shift or slip during the cutting.

Step Three - Cutting the Foam Insulation Board

With your utility knife, score the foam insulation board by firmly running the utility knife along the outer edge of your straightedge. This will result in a small impression or etching in the board.

While cutting the foam insulation board, make sure that your knife cuts to the outside edge, or 'waste area.' If you make a mistake, it will it will not damage or destroy your board.

Once you finish the scoring the board with your utility knife, remove the clamps and straightedge.

Step Four - Completing the Cut

Lift the foam insulation board so that the sheet is upright. Then snap along the scored cut by pressing hard against the backside of the score (etching) line while securely holding the side edges of the board. If you have properly scored the foam insulation board, it should simply pop or snap off. Remember to snap the foam board from the uncut side of the insulation board.