When will grading work?
The Basics:
Water flows downward only in the presence of resistance. If there is little resistance water simply goes downward.
The point above is this: Grading will only make a difference if it is actually stopping the water from soaking into the ground. This requires a very high degree of slope. A nearly unwalkable slope.
When water hits the ground it will simply soak into the ground. It only starts to run off when the ground is fully saturated.
If you basement is 6 feet underground and you slope your yard away at 3/12 slope it will be 24 feet from your house till the water run off is lower than you basement floor. This is a pretty serious slope and yet it will only lower the water volume by about 5% and the pressure at your footer/lower wall area by about 9%. This is pitiful performance for all the work of grading.
The Answer:
Grading becomes a real solution only when the ground outside is sloping toward the house over any considerable distance. This is normally not a landscaping issue but an “earth” issue and often requires a lot of dirt to be moved. If possible try to not have/remedy any areas that have large slope toward the house.
Many people will say, “installing drains to run the water around the house will fix the problem.” This is true! But.. those drains would have to be installed very deep. Installing drainage 2 feet deep when the basement is 8 feet deep will do nearly nothing but make a mess of the yard.
It is often found that some homes are simply in bad spots. There is sometimes not a practical outside solution. This is why so many try to approach the problem from inside.
