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How to Cut an Extruded Polystyrene Sheet

Kimberly Johnson

Extruded polystyrene insulation, also called XEPS, is a form of rigid foam board that is used for insulating homes and commercial buildings. Extruded polystyrene is supplied in sheets, similar to wallboard, and must be cut to fit the walls or other installation area. Cutting an extruded polystyrene sheet is a quick process that requires no specialized tools.

Extruded polystyrene panels can be employed behind a wall, under the roof, or beneath flooring.

Step 1

Measure the wall, ceiling or other installation area to determine the width and length of extruded polystyrene sheet that you will need.

Step 2

Lay the polystyrene sheet on a flat surface -- such as a table or work bench -- and mark the length and width measurements on it using a tape measure and a pencil.

Step 3

Lay a straight edge along the pencil line and use a utility knife to cut 1/4 inch into the sheet all the way down the line.

Step 4

Set the utility knife and the straight edge aside and slide the polystyrene sheet over the edge of the table until the cut line hangs off by 1 inch.

Step 5

Place one hand flat on top of the section that remains on the table and grasp the free edge with your other hand. Snap the free edge downward using a quick motion to snap it off the sheet.