Grading of your land away from the foundation in ME & NH is very important. You need to be sure that the ground slopes away from your home and foundation, so that surface water will run away from your home, and not affect your basement or foundation. That means you need to go out there and look – if it doesn’t appear to be sloping at least slightly away, you should fix it. The surface and ground should slope away from the house with a pitch consistent with conditions in your area.
How much your land should slope away from your home and foundation will largely depend on the type of soil you have, the effectiveness of your gutters and downspouts, amount of shading and shrubbery around the house, and a host of other variables.
In order to create the proper grading and land pitch, you may need to have dirt brought in to raise the grade nearer your foundation. Do not allow the dirt to touch the wood, or go above the sill plate. Alternately, you may be able to lower the land away from the foundation to create the necessary slope to keep water away from the foundation.
Slope the ground away from the outside foundation by whatever method best suits your home and terrain. Extend the slope for at least ten feet. Seed it with a good lawn grass. Sodding is a common practice that prevents washing away of newly graded areas during heavy rains.
If you have a large area of land that slopes toward the house, surface drainage may need to be intercepted and redirected some distance from the house. Dig a shallow, half-round drainage ditch or depression designed to route the water around the house. Sod the ditch or plant grass in it. If a shallow ditch is objectionable, drainage tiles, with one or more catch basins at low spots, can be installed.
Without proper grading and surface water control, all other efforts to prevent basement wetness will likely be futile.