To insulate a cellar door, apply caulk to the door frame, apply foam weather stripping to the door, and install a vinyl door sweep. You need a general cleaner, utility knife, caulk, a caulking gun, foam weather stripping, scissors, a pencil, a door sweep and a power drill.
- Clean the door frame
Use a general cleaning agent to remove all dirt, dust and grime. Use a utility knife to cut off any old caulk. Dry the entire area with a towel.
- Prepare the caulking gun
Place a container of silicone construction caulk into the caulking gun. Cut the tip off the canister, and squeeze the trigger until caulk is visible.
- Apply the caulk
Gently apply caulk to the gap around the door frame, holding the caulking gun at a 45-degree angle. Be sure to keep the gun in place until releasing the trigger. Allow it to dry according to the label.
- Stick weather stripping to the top and sides of the door
Remove the adhesive from the weather stripping, and apply it to the top of the door frame beginning at the left corner. Make sure it stays flush when the door is closed, then trim off the excess. Do the same for both sides of the door.
- Install a door sweep
For interior-opening doors, place the vinyl door sweep on the inside, and for exterior-opening doors, place it on the outside. Use a pencil to mark drill holes. With a bit that's one size smaller than the screws, drill holes on the pencil marks. Screw the door sweep into the holes.