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How to Install Sheetrock Over Rigid Foam Board

Alexander Callos

Rigid foam board insulation is commonly used to help insulate homes. With varying sizes of thickness, this insulation is a great way to save on energy costs. This type of insulation is commonly installed in basements over concrete block, and installing drywall on top of it can give the room a finished and elegant look. Installing drywall over insulation is similar to installing drywall into regular studs; however, there are some added steps to ensure the drywall is properly installed.

Drywall can be installed over rigid foam board insulation.
  1. Multiply the width of the wall by its height to determine how many sheets of drywall will be necessary to cover the insulation.

  2. Mark a horizontal chalk line along the foam board 3 inches from the top of the wall, followed by a line 3 inches from the bottom. Measure from the bottom to the direct center and snap another chalk line. Add one more chalk line directly between the middle line and the top line. The fifth and final line will go between the middle line and the bottom line.

  3. Line up the first furring strip on the bottom chalk line. Drill a hole 5 inches deep with a masonry bit and hammer drill through the insulation and into the concrete walls. Begin at one end and drill a hole every 16 inches. Repeat this process for each of the five furring strips. Drive 4-inch long spring spikes with a hammer into each of the holes.

  4. Connect 1x3 furring strips vertically to the horizontal strips. Space the strips every 16 inches on center across the entire length of the wall. Drill in drywall screws spaced every 16 inches vertically.

  5. Line up the first piece of drywall along the wall. If the sheet needs to be cut, use a T-square and cut along the straight edge with a utility knife. Bend the piece of drywall down and it will snap. Cut the back side to break it off completely.

  6. Drill drywall screws beginning at the top left corner into the 1x3 vertical furring strips. Position the screws every 16 inches all the way down the entire sheet. Go around the entire sheet of drywall, screwing into the top, bottom and the other side. Repeat this process for each sheet, cutting to fit when necessary.

  7. Mud over the seams and screws holes with joint compound and a taping knife. Spread out the mud with a knife to cover any gaps. Smooth out the compound by sanding down the area with a drywall sander.