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Insulating a garage door

An insulated garage door can have a huge impact on the temperature of your garage. If your garage door is adequately sealed against the climate (hot and cold air as well as water), then you can rest easy that your home’s largest door isn’t letting out valuable conditioned inside air, or letting in unwanted drafts, moisture or even insects! See the following tips for help in insulating your garage door.

Adding or replacing garage door weather seals
A good insulated garage door will have a good barrier on the bottom. This is the garage door’s weather seal, and while often neglected, is an important part to sealing off your garage to the outdoors. Replace the weather seal on the bottom of your garage door if it’s brittle, worn or torn. Remove wood door seals with a flat pry bar and attach the new seal with 1-inch roofing nails. Install a new seal with a wide angle of flange to the inside of the door. The hollow rubber weather seal on metal doors is a U-shaped astragal. This type of seal is sized according to it’s width as it lies flat. To further seal a garage door, replace wood door stops with vinyl stops that come with rubber gaskets.

For wooden garage doors, nail one end of the seal, pull it taut, and then nail the other end in, and then nail from the center out. This keeps you from having extra seal on one side as you install.

For metal garage doors, use a regular screwdriver to open channel ends and remove the old rubber astragal. Lubricate the channels with a silicone spray and insert a new rubber astragal.

If the surface directly below your door is uneven, take note. When a concrete slab buckles or sinks, it frequently creates a gap between the garage door and the floor. This gap provides easy access for small creatures, debris, and sometimes rainwater and snow. It can also knock the door out of level, creating unnecessary wear and tear on the door’s hardware and automatic opener. Close the gap using one of these two methods:

You can buy a gap-filling astragal, which will work on the metal or wood garage doors, provided they are installed in a retainer clip mounted to the door. Astragals are available at garage door supply stores in a variety of widths. These work best if your concrete moves with seasonal temperature variations.

You can also try scribing the bottom of a wooden garage door to fit the concrete. Remove any old seals at the bottom and close your door. Using a small piece of wood that is the same thickness as the widest part of the gap, tape a pencil to the wood and slide the wood and pencil down along the ground so that you are tracing and transferring the concrete’s curves (profile) to the garage door. When you’re done you’ll essentially have a pencil line along the bottom of the door that matches the line on the concrete below. If you cut your wooden garage door along this line, install a new weather seal, your garage door will close tightly on the uneven surface, helping you to drastically increase insulation in your garage.

Finally, an easier fix to the uneven problem can involve buying a long strip of foam pipe insulation (about 3/4″ in diameter) and nailing it to the back edge of the door. Use 4d box nails.

When sealing off a garage door, be sure to turn the lights out in the garage during the daytime and stand back, looking for slivers of light coming through. You may notice some at the jambs. These can easily be filled with a light bead of expanding foam insulation. If you see light lines on the door itself, you can apply some paintable caulking along the edges where the panels meet.

Of course, if you are up for the investment, you can buy fully insulated garage door panels and install them in place of your hollow panels. Insulated garage door panels help guard against the sun’s heat rays from the outside, while keeping the garage warm and cozy during the winter months (as long as you have a small heater going!). If the expense is too much, it’s easy enough to purchase 1-2″ insulated foam panels at the home center. Just cut them to size and place them on your door; metal garage doors sometimes allow you to just sit the insulation inside along the rails. Wooden garage doors may require you to affix foam pieces using construction adhesive.

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