Within the last year, I have purchased an 80+ year-old house. The house has a sealed blacktop driveway that runs parallel to the house. The house has an integrated garage with swing-open (horizontally opening) doors. The garage floor is about 2-3 inches lower than the driveway, with the bottom of the doors being below the drop-off where the driveway meets the garage floor.
The garage gets some water in it, and when it storms it gets a lot of water. For the first time, we realized that the water may possibly be coming in through this gap since there's nothing to stop it (as opposed to general foundation leaking).
Is there a barrier method we can employ on the outside of the garage? Installing a french drain or similar mechanism would be extremely difficult due to the placement of the driveway and the garage, but laying those water-inflatable barriers would not be an option for freezing temperatures. How would I build such a barrier, and of what material? I'd like to keep the profile of the barrier as low as effectively possible to be able to use the garage from time to time.