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The Inside Outside Guys: French drains — rediscovering an old solution

By Ken Calverley and Chuck Breidenstein
Special to The Detroit News

Thunderstorms and heavy rains are beautiful events unless you are a homeowner who has experienced a flooded basement or crawl space.

Basement water is usually the result of misdirected surface water. While many homes have rain gutters and downspouts, the resulting water flow is often toward the house and the foundation.

Those downspouts should be connected to another pipe; this one buried in the ground and directed away from the house. It is a form of what we call a French drain, likely named after the early American farmer who popularized the concept of installing ditches and sub-grade pipes to drain crop fields.

In its simplest form a French drain is a perforated pipe laid in a bed of stone. The stone creates a path for water to enter the pipe where it is then directed to an acceptable terminus, perhaps a roadside ditch.

House foundations have long used the concept to direct ground water to a sump crock in the basement where the water is pumped up and away from the home. These drains are often called weep tiles since their early construction was clay tiles roughly butted up against each other and laid in a level perimeter around the footings to intercept and slowly redirect ground water to the sump.

French drains have been recently “re-discovered” as a means for homeowners in small-lot subdivisions to deal with ponding water. Such subdivisions are generally built with perimeter swales running through them to direct surface water to an acceptable end point, perhaps a ditch or nearby creek.

But decades of owner landscaping and modification often render these swales ineffective with the result being many homeowners will have periodic ponds in their yards. One solution might be to create a swale in the yard, which directs the water to the gutter at the street’s edge. Where this is not possible, another alternative might be a French drain.

This type of drain will be intended to detain the water below ground level where it will slowly “weep” into the surrounding soils. It may consist of a series of shallow small diameter (6”) pipes run horizontally or larger pipes run vertically down into the ground. In some cases a single large diameter pipe is located vertically with many smaller diameter pipes running away from it – sort of a spider’s web configuration.

The central idea is to get the water away from the home’s foundation and below the lawn so that ponds don’t create breeding grounds for insects or kill the grass.

The simplest system today will consist of a corrugated and perforated plastic pipe that is “sleeved” with a filter cloth. Ideally the pipe is surrounded by stone, often pea pebbles. This “stone bed” is then wrapped by another filter fabric.

The filter fabric is intended to make sure that, over time, very small particulate we call “fines” in the soils do not get into the drain where they might settle and eventually plug up the system. These fines are what often plug up a homeowner’s weep tiles surrounding the basement.

Where a large diameter pipe, buried vertically, is the core of such a system, there may be a removable cap or lid on top of it to allow for periodic inspection and, if need be, cleaning and pumping.

So, if you’re a homeowner dealing with surface water issues, know that there is a solution. Direct the water well away from your home and possibly use French drains to keep the water out of sight and out of mind.

For more home improvement advice listen to the Inside Outside Guys every Saturday and Sunday on News/Talk 760, WJR, from 10:00Am-12PM or contact us at insideoutsideguys.com with your questions.

Protect your basement -- and everything in it -- with a French drain.

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