InspectUSA Tool Tips & Useful Info

Written by John Klima

When a homeowner is having problems with water getting into his basement, he will most often consult a waterproofing company. Although this seems like an eminently reasonable thing to do, it may not be the best first step. In my 23 years of experience as a home inspector, I have seen many cases where a water proofing company has installed sub slab drain tiles and a sump pump when it wasn’t really necessary.

Many wet basement problems are the result of conditions that can be corrected by the homeowner himself, or with the help of a landscaper. Please note that I say many, not all. There are situations where the services of a waterproofing contractor really are needed. Before consulting a waterproofing company, you should examine the conditions around your house yourself. You may find that the cause of the problem is quite obvious.

The first thing you should look at is the condition of your rain gutters and downspouts. If the gutters are full of leaves and debris, they cannot function, and the water from the roof will just pour of the edge of the roof and saturate the soil at the basement wall. Very few basement walls are impervious to water penetration. If the soil outside the basement wall is saturated with water, the water will find a way in.

You should also look at where your downspouts empty out. Typically, the bottom of the downspout will have an elbow on it to direct the water outward, and a concrete splash block underneath to keep the falling water from eroding a hole in the soil. If the splash block slopes away from the house, this may be adequate. If the elbow or the splash block is missing, or the splash block is dead flat, or slopes back toward the house, the water will just collect at the bottom of the downspout, and saturate the soil next to the basement. In some cases it may be necessary to connect a drainpipe to the bottom of the downspout to lead the water away from the house. The pipe may sometimes be left on the surface, but in some cases it is more appropriate to bury it under the soil for either aesthetic or functional reasons.

The second thing you should examine is the foundation grading, where the soil in the yard actually meets the basement wall of the house. The soil in this area should slope distinctly away from the foundation for several feet, so that it drains out into the yard, rather than toward the house. A slope of ½” per foot is considered adequate. If the grading around your foundation is dead flat, or actually slopes down toward the house, this is very likely a contributor to you wet basement problem.

What counts here is the slope of the soil itself. A deep layer of mulch can often hide a reverse slope at the foundation. Before attempting to re-grade at the foundation, you should pull away all mulch and other organic matter, to expose  the mineral soil. When the bare soil is exposed, then you can build up the grade near the foundation with additional soil. When doing this, it is best to use a soil with a fairly high clay content so that it can be packed down to form a layer that is less vulnerable to water penetration. When the added soil is in place, it should be tamped down firmly so you don’t have to wait for it to settle naturally. Once the new soil is in place, it can be protected from erosion by grass, mulch, or ground cover.

The third thing you should look at is the general slope and drainage situation of your lot. If a part of your yard slopes downhill toward the house, it will also drain toward the house. The water draining off that part of the yard will wind up against or near the foundation and will get into the basement. If you have a condition like this in your yard, you will need to re-grade the yard so that it no longer drains toward the house.

In simpler situations, this re-grading may consist of just creating a shallow ditch or swale between the house and the higher ground so that the water is intercepted by the swale and directed around one end of the house. In more extreme conditions, where there is a really steep hill involved, you may need to terrace the side of the hill in one or more terraces.

Another thing that can cause water in a basement is a patio slab that has settled unevenly so that it slopes back toward the house. The drainage from such a patio will run up to the basement wall. Similarly, a sidewalk or driveway adjacent to the house, which drains toward the house, will direct water toward the basement wall.

An additional thing to look for is a hollow or void in the soil underneath a concrete porch or stoop. Such a void commonly develops when the back fill soil settles out from under the porch or stoop. A cavity of this type provides a place for water to  accumulate. If such a cavity is discovered, it can be packed with soil to keep the water out.

In my experience, most water proofing companies will not look for these common sense solutions on the outside of the house. They will just proceed with the drain tiles and sump pump, which can be expensive, and may be avoidable.

In general, what you are looking for is common sense ways to keep water from approaching or accumulating right outside the basement wall. It is much better to keep the water away from the basement wall in the first place than to let it come in and then pump it out with a sump pump. If you need assistance in analyzing your wet basement problem, a seasoned home inspector can often be helpful.

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John Klima has almost 30 years of experience in the field of inspecting residential, commercial and multi-family properties. He is a Maryland licensed home inspector and has inspected over 10,000 buildings.

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This entry was posted on Tuesday, June 2nd, 2009 at 9:51 am and is filed under Home Maintenance. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.