Garage Door Threshold and Seal Replacement in Fort Worth, TX Bottom Seal, Stop Molding, Threshold

The four separate things people call a seal

The bottom seal, sometimes called the astragal, is the flexible strip in the retainer along the bottom section, and on most steel doors it slides into an aluminum channel. The stop molding is the flexible flap nailed to the face of the jamb and the header that the closed door presses against on the sides and top. The threshold is a separate rubber or vinyl ramp bonded to the slab under the door, which is a different product from the bottom seal and solves a different problem. And on sectional doors there are joint seals between sections, which are part of the section rather than a replaceable trim. Diagnosis starts by asking which one is failing, because replacing the wrong one changes nothing.

How each one fails here

Bottom seals go first because the sun reaches them under the door and the slab reflects heat back up. In a climate with a 95.6-degree July normal high at DFW and roughly twenty days a year over 100, vinyl hardens, then splits at the folds and tears out of the retainer. Stop molding on a west or south-facing opening goes chalky and stiff, and eventually the nails pull as the wood behind it swells and dries. Thresholds fail at the adhesive line, usually because they were installed on a slab that was not clean or in weather too cool for the adhesive. The retainer itself corrodes at the fasteners and stops holding the bead of the new seal, which is why the retainer sometimes has to be replaced along with the seal.

The threshold decision

A bonded threshold is the right answer for one specific problem: a driveway that slopes toward the garage, or an apron that has settled so water sheets under the door. Fort Worth thunderstorm days average 46.5 a year and the rain comes hard and fast rather than steadily, so surface water at the door line is a real drainage problem in a lot of older neighborhoods. A threshold also blocks the fine grit and leaf litter that a gust drives under the door. What it does not do is fix a door that will not seal because the slab has heaved or the bottom section is bowed, and it slightly changes how the door meets the floor, so a very worn bottom seal should be replaced at the same time. Where the concern is wind-driven damage rather than water, read the storm and wind damage page.

Sealing is not the same as insulating

A well-sealed uninsulated door still transmits heat through the steel. An insulated door with a torn bottom seal and gaps along the jamb loses a good part of what you paid for. The two jobs work together and the sealing half is a fraction of the cost, so it is the right thing to do first, and often the right thing to do instead when the door itself is sound. If the garage is attached and used as living or working space, the insulated door page covers when the bigger investment is worth it. The service list has the rest.

What the work involves

The door comes down and the old bottom seal is drawn out of the retainer, which is a two-person pull on a wide door. The retainer gets inspected and cleaned or replaced. New seal is cut to the door width with the right bead profile for the channel, because a bead that does not match the channel will pull out again. Stop molding is removed with the nails, the jamb is checked for rot at the bottom foot where water sits, and the new molding is set with a consistent reveal so it just touches the closed door rather than being crushed against it. Overtight molding drags on the door face and makes an opener strain. Thresholds go down on a slab that has been swept, degreased and allowed to dry, with the adhesive the manufacturer specifies.

Pests, light and the test at the end

Two side benefits worth naming. A tight seal ends the gap where rodents and insects get in, which is the reason a lot of these calls are made in the fall. And a proper stop molding line ends the daylight strip along the jamb that makes a garage feel like it is outdoors. The finished check is simple and should be done with you: close the door and look for light along the bottom, the sides and the top, then run the opener once to make sure the new seal has not added enough drag to trip the close force. You get the price up front, and on this job it should be short: seal, molding, threshold if you are having one, and labor.