Stop Molding

Stop molding is a narrow strip of trim nailed to the face of each side jamb and the header jamb of a garage door opening. When the door closes, the outer face of the bottom section presses against the stop molding on both sides, and the outer face of the top section presses against the stop on the header. This gives the door a solid surface to close against, limits travel into the opening, and creates a seal that blocks light and reduces air infiltration.

Stop molding is typically made from 3/4-inch-thick wood or cellular PVC. Wood is the traditional material; cellular PVC is an upgrade that resists moisture, rot, and the painted-surface sticking that can pull paint off older wood stop molding on warm days. Both come in a standard profile: a flat back that nails flush to the jamb face and a stepped front that presents a 1 to 1.5 inch face to the closed door.

On a standard residential installation, stop molding runs continuously up both side jambs from the floor to the top of the opening, then across the header jamb. The jamb seal or perimeter weatherstrip is nailed through or stapled onto the face of the stop molding so it compresses against the door edge when closed.

Over time, wood stop molding can rot, split, or bow away from the jamb. A gap between the stop molding and the jamb allows air, water, and pests into the garage around the door edge. A stop molding that has been nailed too tight against the door face can cause the door to bind or leave paint marks on the door skin.

When replacing stop molding, the new piece must be set so the door rests against it firmly enough to compress the weatherstrip but not so tightly that the door binds or the spring counterbalance cannot hold the door at partial height without it creeping down. Air infiltration test results depend heavily on how well the stop molding and weatherstrip are fitted and maintained.