Adequate drain alleviates flooding at basement threshold

Inspector's Eye

Proper surface grading, adequate gutters also needed to stem water

September 30, 2001|By Dean Uhler

Ron Landy of Woodbine informed me about an incident where he had water flood over his basement door threshold, and he's worried that it will recur even though the builder made improvements to the drain.

He wrote:

"I recently moved into a new home with an areaway - a stairwell leading to a below-ground basement. The bottom of the well has a drain that leads directly to the sump pump. ... During a serious storm in early July, we had 5 inches [of water] in one hour, the drain was overwhelmed, and water seeped under the door to the stairwell and damaged the carpet in the finished basement. I was really angry.

"The builder covered all the costs of the carpet removal and replacement, and this time told me the problem was that their subcontractor had installed the wrong drain.

"It was the small nine-hole, disc-type drain, which appeared to be the same one used in my shower stall.

"The builder drilled out the concrete and replaced the drain with a black 9-by-9-inch drain, which has what appears to be about a gallon reservoir under it before it drains into the 2-inch pipe that leads to the sump.

"The builder assures me this will cover the problem and I should never have a problem again. He also paid to install a battery backup sump pump in case there is ever a power failure.

"I feel better than I did before, but it still seems to be a design flaw - depending on the sump pump to remove the significant amount of water that comes down into the areaway.

"I contacted the county and they said there is no requirement to `daylight' the drainage or direct it to a `drainage field.'"

Mr. Landy, an areaway drain with a 2-inch diameter pipe leading to the sump is typical and generally acceptable.

If you have an unusually large areaway, however, it may need a larger drain or more than one drain. Also, workmanship on all parts of the drain, and at the vicinity of the areaway, must be good for it to function as designed.

The strainer that was initially present was probably substandard.

A rule of thumb is that the strainer should have an open area of at least two-thirds the cross-sectional area of the drain pipe. If you haven't already done so, check for obstructions in the 2-inch pipe by looking into it from each end, at the areaway drain and at the sump, using a small mirror.

Make sure that poor grading at the soil surface around the areaway and house is not causing runoff to drain into the areaway. Ask the builder to regrade if needed.

Check the rain gutter at the roof edge above the areaway during a hard rain to see if it tends to overflow, which can easily overwhelm an areaway drain, and have it realigned or replaced by a larger gutter if it does.

It is true that reliance on a sump pump to prevent flooding is perhaps a flawed concept due to the risk of power failure. But loss of power for a relatively short period of time usually won't result in a flood, because the drain tile under the house is also connected to the sump and can function as a reservoir for water from the areaway drain until power is restored.

Inspector's Eye

Dean Uhler has been a home inspector for more than 12 years and is president of Baltimore-based Boswell Building Surveys Inc. Uhler is a member of the American Society of Home Inspectors (ASHI) and is the treasurer of the Greater Baltimore Chapter of ASHI.

Questions, with name, address and daytime telephone number, about homes and home inspections can be faxed to 410-783-2517, e-mailed to or mailed to Inspector's Eye, Second Floor, 501 N. Calvert St., Baltimore, Md. 21278-0001.

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