How do you keep a lot of rain from coming under a door?

Answer 1

You won't be able to construct a permanent fix until it has stopped raining. During a storm, you could tape a long piece of 3-mil plastic to the outside of the lower half of the door, with a piece long enough to create a sloping away from the door (like a plastic "slide"), say 4 to 5 feet long. Put a brick on both corners outside to hold the plastic down and taut--make sure it keeps a slope instead of sagging or flat. On the inside of the door, remove any throw rug or mat so it doesn't get soaked. (Wall-to-wall carpet will present more issues.) Use rolled up heavy towels to block water on the inside-- remove, wring out, and replace them often. You can also tape several layers of cardboard to the door, even with the floor on the inside, and put rolled up towels in front of the cardboard. Water will seep UP the cardboard layers first before getting to the towels.

The permanent fix is very dependent on the cause. For example, if there is no gutter above the doorway, rain will obviously come straight down. If the doorway is flush with an outside porch or patio (as many are) or is even or slightly lower than an outside surface, rain can easily backflow into the door footer.

So first, identify the cause.

1. If there is a gap under a door, consider adding a flexible door sweep on the inside and outside. Measure sweep with door closed.
2. If your screen door also has a gap at the bottom, consider adding door sweeps there too. Make sure to measure with the door closed to get the proper placement.
3. Look at how you can create a sloping away from the door outside.
4. Consider installing a gutter and downspout to direct water away from the door.
5. Hire a contractor to create a slope.