1. Garage Door Bottom Seal
This is a piece of rubber or vinyl that attaches to the bottom edge of the garage door. The flexible material compresses when the door closes, sealing the gap with the floor to keep water, dirt, cold breezes and mice and insects from getting inside. Some garage doors have an aluminum track on the bottom that holds the seal. This style costs about $40 for a two-car garage door.
A less expensive bottom seal (see photo) is just a single rubber strip that can be attached to wood garage doors with small nails or staples. You'll know it's time to replace the bottom seal when you can see daylight through the bottom of a closed garage door.
2. Garage Door Threshold Seal
This type of seal has the same function as the bottom seal described above, except that it is attached to the floor rather than the door. A good quality vinyl threshold seal can be more durable than a bottom seal. It is installed with adhesive that is usually included in the package.
One potential downside is that the seal will prevent water from flowing out of the garage, and it makes sweeping a bit more challenging. A two-car garage door threshold seal costs about $70.
3. Garage Door Weatherstrip
Wind and rain can also get into the garage around the sides and top of the garage door. That's where garage door weatherstrip comes in handy. You can buy a 30-ft. strip for about $20. Installation is simple, using the enclosed tacks. You will probably also want to install a bottom seal or threshold seal for the garage door bottom.
You can also find a complete garage door weatherstrip kit, which includes everything you need to seal all four sides of the garage door. Installation requires a drill, screwdriver and utility knife. Weatherstrip kits for two-car garages range in price from about $70 to over $100.