If installing the drain involves diverting a stream or affecting a wetland, you likely need a permit to move forward. Generally, a small French drain on your property that doesn't change the flow of runoff entering and exiting your yard won't need a permit.
In some cases, the installation of a French drain may require planning permission from your local planning authority, especially if the drain is part of a larger construction project. You should consult your local planning authority for guidance on any necessary permissions and requirements.
In most cases, if you own the property and plan to install a French drain within your property boundaries, you may not need a permit. However, if the drain is intended to direct water onto neighboring properties, a permit might be necessary.
Depending on the size of your yard and the scale of your drainage issue, you can purchase the pipes and equipment to create a French drain yourself.
The type of drain and its length determine total cost. Installing a French drain costs $500 to $18,000, with a national average of $9,250. On average, you can expect to pay $10 to $100 per linear foot, or between $500 and $5,000 to have a 50-foot French drain installed.
French drain installation specialists, landscapers, foundation repair technicians, basement waterproofers, and plumbers can complete this job.
Clay soil has poor permeability, meaning it doesn't allow water to pass through easily. In such cases, the effectiveness of a French drain may be limited as the water may struggle to drain away from the area efficiently. French drains may not be suitable for areas with high water tables.
French drain depth: About 8 inches to 2 feet deep should be sufficient for many water-diverting projects, though related systems, such as those built around foundations and sub-ground living spaces, as well as the bases of retaining walls, may be deeper.
Swales: A Natural Solution
They're a great option if you're looking for a more natural, eco-friendly alternative to French drains. A swale is typically lined with grass or vegetation that helps slow down and absorb water.
The ideal distance for a French drain from the house ranges from 5 to 10 feet. This distance provides an adequate buffer to keep water from seeping into and around the foundation, which can be a common cause of damage.
You'll likely need a permit since this project may require soil grading to avoid drainage issues. Repairing your floor may be more cost-efficient than replacing it if grading is necessary. No permit may be required to hang drywall on exposed wooden wall studs in your garage.
Officially a French drain is a gravel drain with no pipe. The water just collects in and travels through in a gravel or stone filled channel that starts from the surface or just below it. But in modern times, and for practical purposes, we will consider a French drain to include a drainage pipe in the gravel.
If installing the drain involves diverting a stream or affecting a wetland, you likely need a permit to move forward. Generally, a small French drain on your property that doesn't change the flow of runoff entering and exiting your yard won't need a permit.
Make sure you excavate the correct pitch (or slope) of your French Drain installation so that water drains into a sump, catch basin, or other drainage feature. There should be a 1-foot drop (sloping downward) for every 100 feet of pipe.
Connections to a public sewer are called direct connections. If you want to connect to a private drain, you will also need to obtain permission from the drainage owner. Connections to a private drain are called indirect connections. Moving a public manhole is called manhole relocation.
Depending on the placement and length of the PVC pipe, you can expect to pay between $2,800 and $6,500 for a French drain. The national average cost of a French drain, across projects of all sizes, is $5,000.
Connect with local French drain experts to help with your project. Installing a French drain yourself is possible but labor-intensive and time-consuming. Call 811 a week or two before you start your project to get your buried utility lines marked.
A properly designed French drain system does not require an outlet. The water will simply soak into the soil as it flows along the perforated pipe. In fact, a French drain doesn't require an inlet on just one end either. You can construct the drain to accept water along its length, and disperse it underground.
Although French drains are low-maintenance, they are not entirely free of potential issues. Over time, the system can become clogged with silt, roots, or debris. When this happens, water may pool again in areas the drain was meant to protect. Regular inspections can help identify problems early before they escalate.
A French drain needs to be surrounded by gravel in order to filter out silt and prevent clogging the drain pipe.
The optimally installed French drain does not necessarily need an end point. Ideally, as the excess water from one area runs down the drain, it will be distributed more evenly across your yard and absorbed.
Landscapers have the expertise to work the French drain installation into your existing landscape design, ensuring it not only functions well but also doesn't interfere with your yard's aesthetics.
To minimise this risk, a French drain should be positioned at least a metre away from walls, rather than directly next to them (though this may minimise its benefits for treating rising damp).
Efficient Water Management
Preventing Basement Flooding: French drains, particularly exterior French drains, are excellent at keeping basements dry by channeling water away from the foundation before it can seep inside. This can significantly reduce the risk of basement flooding and the associated costly repairs.