How do I Seal a Concrete Sloping Garage Door?

Written by kenneth crawford
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How do I Seal a Concrete Sloping Garage Door?
Remedy the slope under your garage door with a threshold seal. (luxury house image by yong hong from

Garage doors include a bottom weatherstrip to prevent rain and snow from entering the garage when the door is down. If your concrete garage floor has a slope under the door, this thin seal on the door has little effect against the outside elements. Installing a garage door threshold seal, a hard rubber seal with a ledge, on the floor will ensure rain and snow cannot enter your garage, even if it is built on a slope.

Skill level:

Things you need

  • Garage door threshold seal
  • Utility knife
  • Tube construction adhesive
  • Caulking gun

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  1. 1

    Open the garage door and lay the garage door threshold seal between the door tracks with the 45 degree hump pointing inside the garage. Cut the ends of the threshold to fit in between the door tracks with a utility knife.

  2. 2

    Stand inside the garage and lower the door over the threshold seal. Push the hump of the seal against the back of the garage door. Trace the outside edge of the seal onto the garage floor with a pencil. Raise the garage door and move the threshold out of the door opening.

  3. 3

    Sweep the area where you plan to install the threshold seal. Then insert a tube of construction adhesive into a caulking gun and cut the tip of the tube nozzle at a 45 degree angle with the utility knife.

  4. 4

    Turn the threshold seal over so that the bottom is facing you and the seal is flat. Apply thick beads of construction adhesive along the bottom of each side of the threshold seal, 2 inches from each edge. This gives you two beads down the length of the threshold. Apply a third bead of adhesive in between the first two beads in an up and down fashion resembling waves.

  5. 5

    Slide the threshold to the door opening and turn it over to set it against the concrete floor. Line the outside edge of the hump side with the pencil line on the floor. Press down on the entire length of the threshold to spread the adhesive uniformly across the threshold and the floor. This will ensure the threshold bonds tightly with the floor.

  6. 6

    Close the garage door over the threshold and leave the door down for a minimum of 24 hours to allow the adhesive to cure.

Tips and warnings

  • Thresholds for garage doors are available at garage door dealers and some home improvement centres.

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