How to Seal Cables Through a Roof

Equip a power drill with a drill bit that matches the thickness of the cables and drill a hole through the roof for cables to pass.

Align a specialized sealing collar to the hole and set the collar on the roof. Sink the screws through the edges of the sealing collar with a power screwdriver.

Feed the cables through the neck of the sealing collar.

Move to the attic and pull the cables through the interior space in the attic.

Brush the attic ceiling with a dry scrub brush to remove bits of dust and debris. Spray the ceiling with a greasing-fighting detergent and scrub the area if any oils or grease exists on the ceiling. Let the ceiling dry completely

Feed the cables through a specialized interior sealing sheet.

Pull the sealing sheet up to the attic ceiling. Peel the protective film off the back of the sheet and press the self-adhesive backing to the ceiling. Place a flexible putty knife up the cable and drag it along the surface of the sealing sheet toward the outer edges until you remove all air bubbles.

Move back to the roof. Insert a tube of specialized waterproof, airtight sealant into a caulking gun. Run a thick bead of sealant around the perimeter of sealing collar where it sits on the roof and over screw heads. Ensure the sealant reaches from the edges of the collar to the roof.

Wrap the cable with sealing tape, beginning 2 to 3 inches from the collar and extending 1 to 2 inches onto the neck of the collar. If the ceiling collar has a clamp for tightening, use the appropriate screwdriver to tighten the clamp. Some sealing collars are self-sealing and do not require caulk.