How to Glue Insulation Boards to a Concrete Ceiling

Clean any dust and dirt particles off of the ceiling's surface with a shop vac. The construction adhesive will adhere to the insulation board and the concrete surface better if it is free of loose debris.

Slice the nozzle at the end of a tube of construction adhesive with a utility knife at a 45-degree angle. Poke through the foil cover at the bottom of the nozzle with the metal rod connected to a caulk gun. Place the tube into the caulk gun and press the plunger into the back of it. Turn the plunger handle 180 degrees then press the release button.

Start at a corner of the ceiling and use full pieces of insulation board where possible. Use the utility knife to cut pieces to fit into smaller areas. Lay the insulation board upside down on a flat surface and apply a bead of construction adhesive in swirls over the entire surface of the board. Apply the adhesive to two boards at a time so that you always have one ready to go and can work with few interruptions.

Allow the adhesive to set up for three to four minutes then press it into place on the concrete ceiling. Push all of the board against the ceiling and ensure it sticks to the ceiling before releasing it. Continue installing insulation boards on the rest of the ceiling's surface.