Proper Drainage Around the House
One of the most important things you can do to maintain your home is to keep water out of the structure. Keep in mind the mantra that water always wins.
If there is a crack or a gap and a slope toward the structure, gravity will carry water into the house.
Here are a couple of simple diagrams that show how water should be managed on the outside of the home to keep it from getting to the inside:

Diagram 1 shows proper drainage around a house. In Diagram 2, a down spout discharges onto the roof causing premature wear. An inexpensive extension is the solution.