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Putting In A French Drain? Complete These Preliminary Steps Before Digging Begins

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If you've decided your home needs a French drain, you may be itching to start digging right away. Before you get going, though, you'll need to handle a few important tasks to help the installation go smoothly. Here are some vital steps for planning out your drain project.

Getting The Necessary Permissions

While it's fine to do the occasional digging in your garden, big projects like placing a French drain will require government permissions before you can get started. Depending on the zoning laws for your area, you may have to submit plans for your project for review before a permit will be issued, so it's important to handle this step long before you plan to start work. There is a chance your permit will be denied the first time, so you need to give yourself plenty of time to reapply after making the necessary changes to your plans.

Visiting your municipal zoning office is important anyway, since you'll need to find out about any pipes or cables the city may have running under your home. Damaging one of these during the digging could cost you thousands of dollars and even get you arrested, so be sure your drain installation won't conflict with any of their locations.

If possible, you should also discuss adding the drain with your neighbors. Depending on the placement of the outflow pipe, they may be adversely affected by the redirected water. If you don't get them to consent to the placement of your drain pipe in writing, you could be open to a lawsuit for any damages later on.

Determining The Scope Of The Project

French drains can vary greatly in size depending on how much water you need to redirect, the shape of your yard, and how far you need to move the water. To get an idea of how large your drain will need to be, you'll need to plot out its pathway and endpoints. Use garden stakes at the beginning and end, then mark the intended pathway with landscaping paint, being careful to avoid any buried pipes or cables.

To keep water moving along, drains should have a slope that goes down at least 1 inch per 10 feet. If your land doesn't slope enough or slopes in the wrong direction, the drain will have to be dug deeper in order to maintain the downward angle. Some trenches have to be as deep as 6 feet in order to move water, so be prepared for the project to be more involved than you initially expected.

Once you have an idea of how wide and deep your trench needs to be, you can plan for equipment. Shallow and thin drains can be dug by hand without too much strain, but if your home is subject to frequent near-flooding, you may need to rent professional equipment in order to complete the digging in a timely manner. Large trenches may require more gravel than you can lay by hand, so consider that as well when choosing your equipment.

Choosing Your Pipes

French drains are only as good as their pipes, and the pipe you choose should be fitted to your home's needs. While smaller, more flexible piping is less expensive than PVC, it's only suited to homes with very light water troubles. If your trench will be deep, the weight of the gravel may collapse a flexible pipe over time. PVC pipes are more costly, but are rigid and come in larger sizes, making them best-suited for drains that need to channel large amounts of water away quickly.

Thinner pipes also clog more easily, and snaking them is difficult due to the risk of damaging the pipe wall. This makes PVC a more cost-effective investment if you're worried about the drain clogging up. 

French drains aren't hugely complicated to install, but you could land yourself in hot water if you don't plan carefully before the project starts. Make sure you've talked to everyone affected by the drain and you're sure of its exact measurements before you break ground for the first time. With thorough preparations made, everything else will be a cinch. For more information about your french drain installation, visit