Insulating a garage door can easily be done in a day.
Step 1: Remove any remnants of pre-existing weather seal along the bottom and sides of your garage door. If the existing seals are still in good shape, do not replace them.
Step 2: Newer doors have tracks along the bottom for the weather seal to fit in. If this is the case, purchase a seal that will slide securely into the tracks. Slip the seal in and use scissors to cut the excess seal once it is in place.
Step 3: For older doors, purchase a universal door bottom seal that can be nailed or screwed into place. Typically these seals will have a wide lip on one side. The lip is designed to face the exterior of the garage. If the garage floor is lower than the driveway, face the wide lip toward the interior of the garage. To attach the seal, start from one side of the door and work toward the other side, placing nails or screws approximately 3 inches apart.
Step 4: Once the seal is properly attached, trim any loose edges that may obstruct the operation of the door. Test the door to make sure it opens and closes properly and clean up any extra nails or screws you may have left on the garage floor.
Step 5: Install garage door weather strip along the exterior sides and top of the garage door. Exterior garage door weather strip is available as a flexible vinyl roll or ridged wooden/PVC pre-cut strips. Either way, close the garage door before installing the weather strip. For a tighter seal, cut the ends of the weather strip at a 45-degree angle where it meets in each corner. Begin installing the weather strip on the top, working from one corner to the next. Nail, staple or screw the weather strip to the door jamb, spacing the nails, screws or staples approximately 3 inches apart. Make sure the lip of the weather strip rests evenly along the face of the closed garage door. Repeat the process on both sides of the door jamb.
Step 6: Uninsulated metal doors and lightweight wooden doors also will benefit from the installation of an insulating radiant barrier such as Reflectix reflective bubble insulation. To install the insulation, measure the panels of your garage door from the inside. Cut pieces of Reflectix slightly larger than each panel. Fold the edges of the insulation to the back of the sheet and press the sheet up into the metal channels framing each panel. For wooden doors, fold the insulation edges to the back and staple each sheet directly to the door panels. The application of Reflectix tape around the edges of each panel will assure your sheets stay in place. When finished, each insulating sheet should bow out slightly from the panels, creating an efficient air space behind between the two. Keep the insulation and tape free from the moving parts of the garage door to avoid obstructing the use of the door.
Open and shut your garage door a few times, watching from both the interior and the exterior of your garage to be certain your door operates properly. Pack away your tools, recycle the leftover materials and close the door on another job well done.