Proper Drainage Makes for a Dry Basement

by Murray Anderson

Damp basements aren't just unpleasant places to spend time, they can be hazardous to your health as well. Since mold needs moisture to grow, if your basement is dry not only can it be a pleasant place for your family to spend time, you won't need to worry about any health impacts mold could have on your family. While having good drainage underneath your foundation is important in ensuring a dry basement, controlling surface water is equally critical to ensure your basement stays dry and your family enjoys a healthy environment to live in. Here's some thoughts on how you can control surface water around your home.

It's not just a little rain

Many people are amazed when they learn just how much water can run off their roof. It's estimated one inch of rain falling onto 1000 square feet of roof translates into over 600 gallons of water. With that amount of water,you can see why it's important to get it well away from your foundation.
Since most roofs are sloped to guide the water to their edge, the first step is having working eaves troughs to channel the water to downspouts that guide the water well away from the foundation. If rainwater is allowed to just run off the roof, moisture will build up around the outside of the foundation walls and eventually work its way through the 'solid' walls.
Installing extensions onto the tail end of your downspouts extending out at least six feet from your home will help guide the water well away from your foundation. If possible having the extensions drain onto a solid surface (driveway?) will help ensure the water doesn't soak in close to your foundation walls.

It's not just roofs that should be sloped

The ground around your home (just like your roof) should be graded or sloped away from your home. A slope of between 1 and 1 ½ inches per foot for at least 6 feet (10 is better ) all around the perimeter of your home is enough to help drain moisture away from your foundation and keep rainfall from soaking in close to the walls.
When builders back fill around a new home the earth close to the walls can get compacted so the ground actually ends up sloping towards the walls rather than away. Fortunately it's relatively easy to add extra soil around the foundation and create the proper slope.

Trees look nice, but...

Trees in the yard are beautiful but it's important to realize that as they grow they can cause significant moisture problems around a home . The US Department of Housing and Urban Development recommends no tree be planted closer to a home than it's mature height since when trees are closer to a home, their growing roots could reach out and block any perimeter (underground) drains. Trees can also cause compacting of the soil around the foundation if their roots take up all the moisture from the soil close to the foundation walls.