Your garage door is not meant to just let your car in and out of its storage space. It should also provide a good barrier against the elements — namely rain and snow. If you're noticing water pooling under your garage door after it rains outside, then something is amiss. There are a couple of simple repairs you can make at home to address this issue.
Replace the Weatherstripping
Chances are that there's a thick tube of rubber that runs along the bottom of your garage door where it meets the floor or driveway. This weatherstripping is meant to create a flexible barrier between the outside and inside, stopping water from flowing under the door. But as the weatherstripping ages, it can start cracking and peeling away from the door, creating gaps.
Inspect the weatherstripping, and if you see cracks or if it feels very stiff, set about replacing it. You may need to undo a few screws in order to peel the existing rubber strip off of the door. Take it with you to the hardware store to ensure you buy another strip of the same size. When you get home, measure the width of the bottom of the door, and use a pen knife to cut your new weatherstripping to that size. With the screws loose, push and tuck it into place, and then tighten the screws to hold it down.
If the weatherstripping is in good shape, then perhaps there are a few holes in the door itself. This is most likely to happen to wooden doors. The wood starts rotting along the edge of a board or two, creating a little hole. And water flows through that hole, dripping onto your garage floor.
If you do come across some holes, there are a few ways to seal them. You can use wood filler from the hardware store. Just squeeze some on, and use a scraper to smooth it out. Another option is to fill the hole with caulk. This works as well with materials like fiberglass as it does with wood. Purchase a silicone caulk tube, and cut the tip so that the opening is very small. Squeeze enough caulk to fill the hole or crack, and then smooth it with your finger or a caulk scraper.
If you cannot figure out why your door is leaking, contact a garage door repair specialist in your area, or click here for info.