Ignoring Poor Drainage Can Be Costly Mistake
But poor drainage can build into costly repair work for a patio, pool and/or home foundation. If it creates runoff, it can carry all kinds of polluting materials toward the house or into the street – where gutters and storm drains will take it to the nearest natural body of water.
"Sometimes, just seeing that something’s wrong can be difficult," said Dan Rogers, Kansas State University Research and Extension engineer. "It may be seasonal or develop over time. People can go for years without realizing they have a persistent problem, simply because High Plains weather varies so much.
"Besides, if you’ve got warm, humid air indoors, that certainly can mask some of the symptoms."
Drainage woes tend to become obvious after a foundation develops cracks.
"Cracking is fairly common. Soil is always shrinking and swelling in line with moisture content and temperature changes. The clay content in soils across much of the High Plains exaggerates these effects," Rogers said. "Then poor drainage can provide the moisture to leak through unrepaired cracks. It can build up enormous water pressure on a foundation, enlarging existing cracks and creating new ones.
"I’ve seen cases where poorly built concrete-block basements literally imploded."
Identifying the cause of poor drainage also can be difficult, he warned. Water sources can include surface runoff from rain or sprinklers, supersaturated soil, an underground spring, and/or a high water table. A source may be constant, seasonal or an occasional "event." Homesite factors that may be helping water turn into a problem include paved surfaces, bare soil, the yard’s slope, lack of plantings, soil type and house design.
"I always recommend that every homowner periodically check their homesite to see what happens to runoff during a rain," Rogers said. "Surface runoff is the most common reason for drainage problems.
"Fortunately, some of those problems can be fairly easy and inexpensive to fix. And they’ll already be taken care of, if you find you’ve got a further factor that’s going to require hiring professional help."
The engineer suggested the following check points:
* Does rainwater quickly soak into the ground? Does it puddle or create runoff in certain places? Do you need to be thinking about adding fill dirt or improving clay or silt soil with organic matter?
* Does your yard slope away from the house – dropping 6 inches in the first 10 feet from the structure and at least 1 foot per 100 feet beyond that? Overall, is the slope gentle enough to let gravity move excess rain toward the street, yet allow at least some of that water to be absorbed by the soil? Does slope keep your house at least 18 inches above street level? Can you make any needed changes without raising the soil level next to your house and thus increasing the odds for a termite attack?
* In contrast, does runoff from the street, a neighbor’s house, a hill, a patio, a play area or the like end up draining toward your home? Does your yard effectively divert that water, allowing it no closer than 20 feet from the house?
"Solving this kind of problem can seem impossible," Rogers said. "But a series of low ridges and shallow depressions in your landscape can channel surface runoff. I’ve also seen homeowners do the job by digging a 3-feet deep channel that’s 1- to 2-feet wide and filling it with some porous material, such as gravel. Taking care of minor problems sometimes requires no more than improving the soil, building a raised flower bed, or putting in plants and mulch."
* Are basement window wells collecting water? Do they need a cover? Has the ?fill" soil next to your foundation started to sink or settle, so that it’s directing and/or holding water next to your house?
* Are the gutters on your home’s eaves in good repair, firmly attached, free of debris and sloping toward a downspout (a minimum 2 inches from the high to low ends on a 30-foot run)? If you have no guttering, do you have an effective substitute, such as a ground-level, drip line, gravel-and-pipe system that’s connected to a catch basin?
* Are downspouts carrying water at least 10 feet from your house? Do you need a splash guard where the water exits, to absorb some of the energy the water is using to gouge out gullies?
*If you have a basement – even one with a footing-level drain tile system – does it never seem to dry out? Does it seem increasingly damp? Have you noticed clear subsurface water leaking in?
"Some communities now require drain tiles, as well as a guttering system on new homes with basements," Rogers said. "But at least one Kansas building code left out the additional requirement of a sump pump or gravity system, to get the collected water away from the house. The tiles there were concentrating that collected water underground and next to the foundation, creating a structural threat."
Muscle and common sense can improve many surface drainage problems, he added. But re-sculpturing a large-scale landscape slope can seem worth the cost of hiring someone with earth-moving equipment. Working with underground systems requires trained help.
"If your problems seem to go beyond the obvious, you’ll want to investigate the alternatives and look for a reputable specialist," Rogers said. "In particular, I’d never advise doing anything with your foundation other than repairing cracks, adding a little fill dirt or perhaps painting indoors with waterproofing.
"When you move dirt away from foundation walls, you can put your entire home at risk."