Replacing Garage Door Bottom Seals


It’s that time of year again. Time to prepare your garage door for the upcoming winter months! To prevent cold air and critters from entering your garage it is important to inspect and if needed replace the garage door bottom seal. Replacing garage door bottom seals is a simple process and can be done as a DIY project, or with the help of your garage door repairman. The trick is finding the right product for your garage door.

garage door astragalLet’s begin by explaining what the seal is and what it accomplishes. The seal, which is technically known as the astragal, is the rubber gasket which slides into the metal “retainer” that is attached to the bottom of the garage door. The seal is usually black or grey in color. The purpose of the seal is to protect the bottom of the garage door from the floor each time it opens and closes. It also is used to close the gap between the door and the ground. Most garage door floors are not perfectly even from one side to the other so the seal helps the door become flush with the ground sealing all gaps. Replacing garage door bottom seals helps to prevent cold air, rain, debris and pests from entering your garage.

Garage door seals, or astragals, come in different forms. Not all garage doors use the same astragal retainers, so it is important that you purchase the correct product. The most common types are:

  • Bulb: This seal has a bottom circular shape with a Large T-shape on the top.
  • J-Type: This seal is J-shaped and is used on single channel retainers.
  • Beaded: Beaded seals are T-shaped and are used for double channel retainers with circular grooves.
  • T-type: The T-type seals are similar to beaded seals, and form a T-shape on both sides. They are used for double channel retainers. Astragals also come in different widths up to 7″.

If you are not sure what you need, just snap a picture and send it to us! We can identify what you need and install it for you, or you can take it to the local hardware store and purchase it yourself.

Replacing garage door bottom seals is easy to do. Here are a few tips to help you out:

  1. First, open the garage door to a convenient height that is easy to work on. If you have a garage door opener, the door should stay open on it’s own. If you don’t have an opener, use vice grips on each side of the vertical rails to hold it up.
  2. If you are replacing both the retainer and the astragal, you can simply unscrew the retainer from the garage door and discard it without removing the astragal.
  3. When replacing the astragal it can sometimes gets stuck in the retainer. Spray some WD40 or silicone-based lubricant to loosen it. A dish soap mixture works well too. You also might need to open the channel using a flat bed screw driver and cut the astragal into smaller pieces. Usually it will slide right out.
  4. Next inspect the retainer. Straighten and clean it if necessary.
  5. When installing the new astragal, it is much easier to do with another person. Spray the retainer again if needed. One person will insert the seal, making sure it is riding in the tracks, while the other person guides it through the retainer to the other side.
  6. Leave a small bit of excess on each side to be sure the outside corners of the garage door are completely sealed up.
  7. Next shut the garage door. Inspect for any gaps.  If needed you can slightly lower the retainer in the problem areas. If you have large gaps a 7″ astragal will be needed. Your garage door repairman can also adjust the limits on your door to help it seal tighter.

When preparing for winter, don’t forget about replacing garage door bottom seals. Anderson Garage Doors can help you inspect and replace your bottom astragal and retainers. We carry a variety of styles and sizes. Let us help you keep your home energy-efficient and secure this winter!



Anderson Garage Doors is Logan Utah’s #1 garage door retailer and garage door repair service. Fill out the form below or give us a call at (435) 752-6677 to get started!

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