How to Soundproof a Ceiling With Blow Foam Insulation

Prepare the room by removing all the furniture from the floor. Cover the floor with a painter's tarp to protect the carpet or flooring from overspray. Tape off any light fixtures with masking tape. Drape the walls with plastic to also protect them from the foam, using masking tape along the edges to hold it in place. Turn off the lights. Set up a fan to exhaust the air from the room to an outside area.

Put on goggles, a dust mask and a disposable painter's suit that covers your head with a hood to keep the wet foam from getting on you.

Spray the foam across the ceiling starting at a corner of the room. Work in 6-foot square areas, keeping the thickness even. Move to a new section and continue spraying evenly. Spray around light fixtures or other objects on the ceiling and then fill in the rest of the squared-off area. Keep the thickness recommended by the manufacturer’s directions.

Allow the ceiling to dry completely for the time recommended by the manufacturer, usually several hours. If the finish is not smooth, apply a second coat and wait for it to dry. Carefully remove the masking tape around the ceiling fixtures, dropping it onto the tarp on the floor. Remove the masking tape along the walls and drop the plastic sheets to the floor. Roll up the floor tarp with all the plastic and tape and take outside. Turn on the lights and bring back in your furniture.