Report

This letter is a follow-up to our investigation of the moisture problem in the crawl- space of your home. We noted that the soil in the crawlspace contained a high moisture content as a result of water infiltration into the crawlspace along the front foundation wall.

In our opinion, the source of the water is largely subsurface ground water. Rainwater landing on the ground in front of your house does not readily run off because of the depression in the lawn and flat grade on either side of the depression. The rainwater seeps into the soil at this location and flows underground to the crawlspace. The roof downspouts may also be a source for water getting into the crawlspace.

To correct the wet crawlspace problem, we recommend that you do the following:

Surface Water – Make sure that water coming from the roof downspouts is directed away from the front foundation wall. Your present drainage system may be working okay, but to be sure, we recommend that you check the system during a heavy rainstorm.

Solution A – Install a perforated drain along the inside of the front foundation wall footing and along eight feet of the footing on either side of the house. Outlet the drain at the rear of the house. Maintain a 1/8-inch per foot pitch in the outlet pipes. Use 4-inch perforated corrugated polyethylene tubing, ASTM F-405. Install the drain according to the attached sketch. You can purchase the tubing at Advanced Drainage Systems, Inc., 3927-B Morris Field Dr., Charlotte.

Solution B – Install a perforated drain on the exterior side of the front foundation wall. The bottom of the trench should be at the same elevation as the bottom of the front foundation wall footing, if possible. You can raise the bottom of the trench if conditions require it, but try to keep it at least 6 inches below the ground in the crawlspace. The lower you can make the trench bottom, the more effective it will be. Outlet the drain at the rear of the house. Maintain a 1/8-inch per foot pitch in the outlet pipes. Use 6-inch perforated corrugated polyethylene tubing, ASTM F-667. Install the drain according to the attached sketch. Make sure the drain is well bedded in crushed stone to prevent it from being crushed by the trench backfill. You can purchase the tubing at Advanced Drainage Systems.

If we can be of further assistance, do not hesitate to call.

Sincerely,

William A. Stanton, P.E.