My garage door is fairly new (2yrs maybe) and still has a good rubber seal on the bottom edge (no tears or dry rotting and still flexible). When it rains a lot, there is a considerable amount of water that seeps in at the corners. Is there an effective way of "waterproofing" the door? What types of materials do I need? Should I install a threshold? And finally, how should the door be sealed around the sides and top?

There should be a rubber or vinyl drip edge along the sides and top of the door frame, is there one? The bottom can't be made water tight but you can build a small dam on the floor right behind the main rubber seal using a good silicone caulk. I am talking about something about 4-5 " at each side. Apparently your apron is slightly picked in the wrong direction.

Yes there is a drip edge (1/2"-3/4" rubber flap) on the top and sides. When you say "apron", are you talking about the rubber seal on the bottom of the door or something else? Thanks for your help.

The apron is the concrete from the door out towards the driveway. It should pitch down and away from the garage to avoid letting water into the garage.

You can also purchace a rubber threshold... it is installed under the door and apoxied to the floor. If you cut it in tight it will keep out 99% of the water. I have installed them and all my clients say they were awsome. I am sure lots of places have them... menards has them for around $70.00
Mike

I picked up a threshod at menards for $35. Installed it yesterday... waiting for rain :)