Water in crawl spaces

Here in the Seattle area we are known to receive a fair share of precipitation. It is no surprise to me  when I crawl under a home and find ponding, pooling water. Modern homes typically have a footing drain installed around the exterior foundation perimeter during construction. Inside the space they may also have a footing drain. Sometimes these systems are inadequate or have been crushed during back filling. I see so many interior footings drains clogged with mud, and some are roughed in but never cut to length.

Water is a destructive force. It has been called the "universal solvent" and there is some truth to that. In a crawl space standing water may reduce the load bearing capacity of the soil to cause footings, and foundations to sink.

A more common concern is the elevated levels of moisture in the crawl space. These levels create an environment that is conducive for wood destroying organisms (WDO's). In my service area, I see mostly fungal wood rot decay as the most common WDO. However I do see Anobiids, (wood boring beetles), Dampwood Termites, Moisture  and Carpenter Ants.

It is very important to correct the drainage defect in order to remove the conducive conditions for these WDO's.

Here is a crawl space that has been neglected for years. Water was allowed to pool in the space, with no vapor barrier, and inadequate crawl space ventilation.

The floor system is significantly weakened as a result of Anobiid (wood boring beetle) activities and fungal wood rot.

Sometimes the water problems in the crawl space can be directly attributed to a defective gutter system. It would amaze many people how much water the roof system collects. When this water is discharged at the base of the structure, it is no mystery that it will find its way to lowest point, which is under the home.

The worst drainage problem I have ever encountered was several years ago on a beautiful high end home near Snohomish. The home had been meticulously maintained by its' owners, and during the inspection I was not finding any material defects.

Upon entering the crawl space everything changed. The crawl space clearance was 6 feet plus. The deepest end of the space was about 12 feet. The problem was that the water had no where to go. It continued to fill up this space until it looked like a swimming pool. The only dry ground in this space was at the access, and along some of the upper concrete footing ribbons. Everything else was a pond.

I wish I had before and after pictures, but this inspection took place before I was using digital cameras as an inspection tool. The water lines on the foundation were over 5 feet high in some places.

Needless to say the sellers' were shocked. Like most homeowners, they never entered their crawl space. The house was new when they purchased it, and they had no reason to believe a problem existed. I know these folks would have had the problem addressed had they been aware.

After pumps were installed to remove the water, it was found that an underground spring had changed course and was dumping water into the space. The drainage contractor came up with a permanent system designed to remove this water.

...And the buyers, they did purchase the house.