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Of all the possible defects that can be found in residential construction, the biggest contributor to major costly repairs is poor drainage. The drainage system of residential construction starts with the roof, gutters, downspouts, and proper grading. In many cases poor drainage is in the design of the house, for example:

The use of undersized gutters

Long spans of gutters without adequate slope

Not enough fasteners on the gutters

Little or no roof overhang

The use of undersized downspouts

Downspouts that terminate without a splash block or ground leader

Not enough backfill around the foundation

Hillside construction with poor drainage

Home built on a lot that is too low

Some of these deficiencies can be corrected at a low cost, while others are too costly to change but can still be dealt with in different ways. For example, a home that is built on a low lot needs to be monitored and regularly maintained to prevent long term damage due to water.

Poor drainage can cause a multitude of problems; some can even cause health problems related to the build up of mold.

Wet soil in crawl spaces creates humid conditions for mold to thrive. Along with proper drainage, the use of a vapor barrier and open vents will help keep the crawl space dry and deter the growth of mold.

Basements are also a common place to experience moisture problems, even with proper drainage. The best preventative in this situation is regular cleaning and a dehumidifier.

One of the most common mistakes is adding soil around the foundation at levels high enough to come in contact with the wood on the house. This can cause rot and insect infestation.

Another common problem exists because, when soil is excavated to construct a foundation, the soil that is removed usually extends three to five feet wider than the foundation. After the foundation is built, the remaining void needs to be backfilled. Ideally the backfill soil should be compacted to prevent settlement.

The replaced soil is not going to be compacted as well as it was before it was disturbed, and it will settle. This will form a depression that will collect water in the worst place, against the foundation. If this foundation is a basement, that scenario can cause very costly problems. Extreme cases of water and soil pressure (hydrostatic pressure) can result in the collapsing of the basement walls. Hydrostatic pressure is irreversible, and once it starts, if not corrected will result in very costly repairs. Early detection and preventive maintenance is your best defense in the battle with poor drainage.

Proper drainage should lead water away from the sidewalls and the foundation of the house. Here are some tips to help you accomplish this:

Add soil to settled areas

Make sure the downspouts discharge three to five feet away from the foundation

If the downspouts discharge underground, make sure the ground leaders stay clear

Make sure the gutters and downspouts stay free of debris

Keep gutters tightly attached (gutters that are poorly attached allow water to run down the sidewalls and to the foundation)

Caulk any joints where a sidewalk or drive meets the foundation

Check for positive grading around the foundation

Avoid heavy watering of plants or gardens that are against the house

Remember that awareness of proper drainage and preventive maintenance will help keep your wallet high and dry from the flood of costly repairs.