As a professional landscaper, you know the importance of drainage and of making sure that lawns, paths, patios and driveways aren’t ruined by waterlogging. One of the most commonly used drainage solutions is a French drain.
If you want to know how to install a French drain, then this blog post is for you. It may sound like a big job, but it’s not – it’s a straightforward way of ensuring the effective drainage of surface water and flood water.
To help you deliver a job of the highest quality and get good reviews, we’ve put together this short, seven-step guide to installing a French drain.
What you need to install a French drain
If you haven’t installed a French drain before, the first thing you should know is that you don’t need many materials. However, you do need to use good-quality ones.
The landscaping materials you need to install a French drain are:
- A non-woven geotextile fabric that has a stable but open structure – this will maintain the capacity and efficiency of the drain. We recommend Draintex, which is ideal for trench work like this. It’s also great for wrapping soakaways and water attenuation crates
- A perforated plastic drainpipe
- Pea shingle or similar clean, non-limestone gravel
Before you start, a key factor to consider is the depth of the trench. How deep you need to dig depends on the size of your job: depth can range from 0.2m for smaller domestic jobs and up to 6 metres for larger projects.
Similarly, the size of your job also determines the size of the drainpipe you should use. So, large diameter pipes for agricultural applications and large areas, and smaller diameter pipes for domestic and smaller commercial jobs.
How to install a French drain in 7 steps
Once you have your non-woven geotextile fabric, drainpipe and shingle, you’re good to go.
Step 1: Dig your trench. It’s important that the trench is on a gradient. Either position the trench on a natural slope or dig the trench at a gradient – 1% is fine. And make sure that the trench is wider than your pipe – wide enough so you can surround it with the fabric and shingle.
Step 2: Put in your geotextile fabric. Lay the fabric in your trench, allowing it to come up the sides. It’s important that there is enough fabric to lay over the top of the pipe – this step comes later.
Step 3: Fill the bottom of your trench with shingle. About a third of the way up should do it. This will enable the water to keep flowing and reduce the likelihood of blockages.
Step 4: Put in your drainpipe. Lay your perforated drainpipe, holes face down, in your trench. If the holes are the other way up, the drain won’t work as well.
Step 5. Add more shingle to the trench. Make sure you cover the drainpipe with shingle and fill to just below the top of the trench, leaving enough room to cover with soil or a decorative aggregate.
Step 6. Cover the drain with the fabric. You should have fabric sticking out the sides of the trench. Take this fabric and wrap it round the shingle and pipe, ensuring that there are no gaps through which debris could enter.
Step 7. Cover or hide your drain. Depending on the type of project you’re working on, you may want to cover the French drain with either soil or a decorative aggregate.
That’s it – How to Install a French Drain in 7 Easy Steps. Do a good job using quality materials and your drain will deliver effective drainage and filtration, and provide reliable protection from waterlogging.
With over 20 years’ experience in the landscape industry, Growtivation understands the needs of landscaping professionals and has concentrated on providing high-performance solutions with our Product That Works range.
Growtivation’s wide range of professional landscaping systems means we have the right solution for all common landscaping problems.
Find out more about the Growtivation Product That Works range by downloading our Product Guide and your free copy of our Landscaping That Works guide to weed control and geotextile fabrics. Our PledgeMark warranty certifies that our products are suitable for their intended use for your peace of mind and quality assurance.