Installing French Drain Systems
Pooling Water Causes Foundation Damage but Green Landscaping Helps
Mar 17, 2008
Installing French Drain Systems
There are many scenarios where a residential property can have water drainage problems. One of the most common is where a neighbor's property sits at a higher elevation. The rainwater will naturally drain to the lower property and pool in low spots. This can result in foundation damage which results in costly foundation repair. Or, in some areas, it's going to cause basement damage. One direct solution is installing French drain systems.
Any excessive rainwater coming off the roof can be handled with gutter downspouts.
How Does it Accomplish Rainwater Runoff?
The drain essentially creates an underground channel to funnel rainwater runoff from one area to a lower one. It's a very good example of green landscaping. No pumps are used, no pouring concrete, and very affordable. The force of gravity does all the work!
Choosing the Location for a French Drain
Choosing the location for the drain is the most crucial step when planning excess rainwater runoff. The area where the water is pooling is the obvious starting point. The trick is finding a lower spot to divert the water to.
Digging the trench is the physically hardest part of this DIY project. But it carries its own inherent potential problems. Many utilities are buried during residential construction, indeed, all real estate construction. Phone lines, gas lines, and coax laid by cable TV services.
Once a potential trench line has been determined, it's important to get all these services involved to be certain that no lines are cut. Not only will this minimize getting into a major can of worms, it will show that due diligence has been done if things go awry.
Trenching Dimensions
This is the easy part – planning the depth and width of the French drainage system. At a minimum, the trench should be at least 6” wide and even wider depending on the volume of runoff rainwater. As for the depth? Obviously, it should start out at least as deep as the lowest spot where it pools.
But the bottom line is that the level where the water is delivered to must be lower than the pooling area in order for the French drain system to be functional. Ideally, the grade should be one foot drop for one hundred feet of trench length. Check the depth using a level staked string line running from one end to the other.
Finishing the Drain
Now that the trench is done, line it with landscaping fabric. Allow a few inches to overlap the trench's lip on both sides. Next, pour coarse gravel into the trench. Pea gravel will work, but a coarser gravel will drain more efficiently.
Fold the landscape fabric over the gravel. The purpose of this is to keep sand and soil from drifting down into the gravel, hampering water flow. Cover this with a layer of coarse sand to anchor it all, then add soil up to the lever where grass sod will lay level with the lawn. Proceed with the sod installation, and it's mission accomplished!
 |
