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Types of Drainage

Jun 1, 2020 | Services

Draining water has an immense power to shape its environment. Rivers, canyons, and lakes all demonstrate the ways the natural world drains water and eventually transports it to the oceans. Homes, too, have their own systems of gutters, channels, and pipes that carry water away from problematic areas into larger drains and sewers. Ensuring that your home is properly protected means strategically designing a system that defends against water’s destructive power. This post will cover the causes of poor drainage, the effects it can have on a home, and the type of drainage fixes provided by Johnson’s Landscaping Service, Inc.

Main Causes of Poor Drainage

Poor grading: The slope of the ground around structures is critical to ensure that water drains away, rather than towards foundations. Even a flat plane can prove problematic since water will accumulate without moving away from the most dangerous areas. According to SFGate, the ground should drop at least 2-3 inches for every 10 feet away from the house’s foundation.

Soil type: As a general rule, the looser the soil, the better the drainage. The size of soil particles largely determines how loose or dense a soil will be and how well it drains. Clay, the smallest of particles and highest density soil, proves the most problematic for water drainage. Clay is also the most absorbent and expansive of soils, which creates underground movement and pressure that can cause major damage. A layer of clay or dense soil called a hardpan can spell trouble, since water cannot filter through these layers and accumulates above.

Water table: The water table is the level at which soil and gravel is completely saturated with water. A high water table means that groundwater sits close to the surface, giving rain and other surface water nowhere to drain. While the water table in a given area can change with the seasons and climate, low-lying areas are the most at risk for water table issues. These issues can include swelling and shrinking of the earth around structures and water seeping into foundations.

Effects of Poor Drainage

Foundation problems: Poorly drained water proves incredibly dangerous to the critical structures of a home, most notably the foundation. Water accumulating near a home’s foundation can cause the soil to shift and expand, exerting pressure that creates cracks and other damage. This water-induced pressure, called hydrostatic pressure, can apply significant force over extended periods of time. On the other side of the issue, once water eventually drains or evaporates, the soil again contracts and shifts, releasing pressure and increasing the precarity of the foundation. Once a foundation cracks or moves, a whole host of problems can ensue. Walls, ceilings, and roofs can all shift and crack. Doors and windows can shift, stick, and pop out of place. Floors can begin to slope as the foundation continues to move and degrade. Because the entire house rests on the foundation, everything in the home is susceptible to damage as a result of movement and cracking below. The slow, incremental hydrostatic pressure eventually reverberates up through the home’s most important structures.

Wet basements: Water building up against the foundation eventually finds its way within your walls. Signs of water issues can include mold, insects, dampness, smells, and stains. These issues alone can cost thousands of dollars to repair, especially given their stubborn persistence and the difficulty of reaching the problems. More, mold and similar issues are linked to significant health issues like the worsening of asthma and other respiratory symptoms. Beyond the damage these moisture issues do on their own, they can also spread to affect other critical structures in your home like its framing.

Swampy yard: Water accumulation means mud and pools on the surface of your yard. This can kill plants and grass, damage landscaping, and provide a place for mosquitoes and other insects to breed. Children and pets will collect mud and dirt that will inevitably end up inside. Surface water affects the ways homeowners can use their yards, making it tougher to move around and enjoy the space. Swampy yards are less usable, less beautiful, and less valuable toward the eventual sale of the home.

Types of Drainage

Grading: If the ground does not properly slope away from a structure, water will not drain and instead accumulate in problem areas. The way to fix this problem is to adjust the slope of the ground such that the foundation represents the highest point and the ground grades towards the intended drainage area. This area is often just the street or alley, but can also be a French drain installed on your property if necessary – we’ll discuss this later. The process of grading an area involves bringing in dirt to raise the ground level in desired areas and replanting or resodding at the project’s conclusion. Adjusting the grading of a yard can be more labor intensive and expensive than other solutions, but frequently important in preventing more costly and significant damage down the road.

Surface drainage: This solution involves creating an ideal space for water to soak into the earth in a designated place. These spaces are often near the perimeter of the property, away from any structures vulnerable to water damage. One type of surface drain is called a soakaway. The thinking behind a soakaway is simple: dig a hole and fill it with extremely porous material so that water can soak away from the surface and drain back into the ground. Soakaways can either be used on their own, or in conjunction with other types of drainage and grating.

Another method involves borrowing from nature’s playbook and designing landscaping swales or other areas that strategically reabsorb water. Thirsty plants make great tools for taking care of excess water and when properly placed can mitigate major drainage issues. Features like rain gardens and bioswales not only reabsorb water, but have the ability to filter and process it while recharging the groundwater in needed spaces. More, these areas are perfect opportunities to beautify a property and add to the function of a yard.

Underground drainage: While differing in specifics, underground drains always involve burying a pipe or channel with the ability to carry high volumes of water. This involves either perforated, or solid piping. French drains consist of perforated pipes placed in a porous material designed to collect water from saturated areas and deliver it to dryer ones. The perforation allows water to both flow into and out of the pipe, making it ideal for redistributing water across a property. The idea is similar to a soakaway, but also allows for a higher volume of water to move away from problem areas. French drains, like swales and soakaways, have the ability to recharge the groundwater instead of removing it from the area. Local vegetation benefits from this recharge while they help reduce runoff into lakes, streams and reservoirs.

The second type of underground drainage, a solid pipe system, often transports water off the property to storm drains and other high-capacity systems. Professionals will often recommend these systems in places with high runoff. Underground drainage can look like trench drains consisting of long grates on the surface of the ground, or drains that connect to downspouts and gutter systems. Trench drains are ideal in areas like driveways, patios, and other concrete-covered areas with high runoff. Downspout drainage takes another high-runoff area–your roof–and transports the water away from the home’s foundation. This system can be especially important because of the problems of foundation damage discussed above and your roof’s ability to drain hundreds of gallons directly adjacent to vulnerable areas.

Trust Johnson’s Landscaping Service, Inc. For Your Next Project

Drainage, while often ignored or neglected, is high on the priorities of every responsible homeowner. Frequently, poor drainage isn’t the fault of the homeowner, rather, it is often the result of poor grading, poorly draining soils, or a high water table (or any combination of the three, in addition to other possible causes). It can result in major damage to your home’s foundation, its critical structures, and harm the health and well-being of those inside. Moisture-related issues like pests, mold, and rot all cost thousands of dollars to repair and remediate. Replacing and repairing framing and foundations can cost even more.

With improved technology and environmental knowledge, professionals like those at Johnson’s Landscaping Service, Inc. have many types of drainage solutions. Grading a yard might be necessary and effective when the ground level leaves pools of water near structures. Surface drainage like soakaways and swales are useful in absorbing water in safe, designated areas and can add beauty and use to a space. Finally, subsurface drainage can efficiently transport high volumes of water when necessary.

Tracing our origins back to 1933, Johnson’s Landscaping Service, Inc. has decades of experience providing quality service to the communities of Northwest D.C., Bethesda, Chevy Chase, Kensington, Silver Spring, Rockville, Potomac, and Olney. With creativity and commitment, our landscape designers provide custom solutions with unparalleled results. Contact us today for a free consultation.

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About the Author

Matt Johnson grew up in a family of landscapers and gardeners as the grandson of Raymond Johnson (Founder, 1933, Johnson's Florist and Garden Center) and son of James and Carol Johnson (Founders, 1960, Johnson's Landscaping Service, Inc.). Since 2007, he has led Johnson's Landscaping Service with his brother, Charlie.  Matt and his wife Jaime live in Petworth in Northwest DC with their 3 sons and 2 big dogs.

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