If you are suffering from a yard that is constantly underwater or has certain areas that just don’t drain after heavy rain, a french drain might be right for you.
A french drain is a type of draining system that allows pooling water to escape to a lower point in the yard or the street. The main concept behind the design is a slightly sloped trench starting at the area that retains the most water and sloping away towards the street. The trench is filled with round gravel and a perforated pipe to allow the water to run easily away from the house and not get caught in the soil.
The gravel is one of the most crucial components to the french drain as it allows water that has soaked through the ground to be carried away down the slope of the french drain.
However, there are tons of different types of gravel out there and we often hear the question. “What kind of gravel is best for a french drain?” The best type of gravel for a french drain is a hard rock like granite chips or washed river rock. Preferably, the gravel pieces average at least 1″ wide to allow the best surface area for water to run along.
In the set up of a french drain, gravel normally fills at least the bottom one third of the trench and a perforated pipe is laid on top of the gravel to allow even faster drainage in case the water is soaking into the ground faster than can be drained by the gravel. In french drains where there is not a pipe being installed, make sure to get even bigger gravel pieces. Try to get stones 1 and 1/2″ or bigger if possible.
Additionally, it is wise to choose a harder rock for your base gravel so that it doesn’t wear down too quickly. Softer rocks that break down over time will become too small to properly drain the water and will end up clogging the drain.
A french drain can be a super helpful solution to a problem that could end up costing you lots of money if left unaddressed. There are several factors to consider when deciding if a french drain would be worth the investment and what options are available. We will discuss this more in detail below.
Is a French Drain right For you?
While it might not be the biggest home renovation project you could do, installing a french drain is a relatively large investment whether you’re installing it yourself or having professionals do it for you.
On average, french drains cost anywhere from $10-$15 per linear foot for materials and labor and the average total price is anywhere from $1,000 to $3,000.
To get comfortable spending that kind of money, it is always best to know exactly what you can expect to get out of your investment. Here are some scenarios that french drains can be extremely useful.
– Pooling water near the foundation of the house – After a house settles into the foundation over time, the foundation area can often become the low point in the yard and a french drain can be especially effective in routing standing water away from this area.
– Keeping your Basement Dry – Since a basement is inherently below grade, it is subject to lots of water pressure if the soil has a lot of water in it after a storm or heavy rain. A fantastic way to keep water from seeping into your basement from cracks in the concrete is to either install an exterior french drain along the base of your foundation or to install an interior french drain in the basement itself.
– Preserving Retaining Walls – Similar to a concrete basement, retaining walls are also subject to a similar pressure when the soil that is pushing up against them is heavily water logged. Using a french drain to keep the soil more dry and compact will help keep your retaining walls in tact for much longer.
Recommended Products
If you do decide that a french drain is right for you, there are several options available in terms of product choices. You will need to select the type of gravel to fill the trench with and the type of piping to lay on top of the gravel. Here are some of the top products available.
- Mexican Beach Pebble – This is product is an ideal choice for french drain gravel. The stones are roughly 1″ to 1 and 1/2″ wide and are already smooth which is ideal for water to run along the surface of the stone.
- Vigoro All Purpose Decorative Stone – This stone is not quite as wide as the beach pebble but is still a great option for filling your french drain as it is extremely hard and will not wear quickly. The rigid nature of this stone will also be perfect for filtering soil out of the water which will prevent the drain from getting clogged.
- Prefabricated French Drain – This is honestly one of the best french drain pipe options on the market. It is flexible and easy to fit into any trench shape.
It is technically marketed as a draining option that does not need gravel but in my experience, it is best to still lay a gravel base in the trench with this product for maximum results. Because this product is inherently wider than a traditional perforated pipe you will not need to lay as much gravel in the trench and may even need to dig the trench slightly wider.
Helpful Resources
Whether you are preparing to install your french drain or just curious about the additional methods or products available, it is important to do your homework. Here are some of the most helpful resources I found when when initially doing research on the subject.
- Great articles on overall installation process
How To Build A French Drain - Do it Yourself – French Drain Installation
- Here is an in depth, step by step explanation of the french drain installation process.
Final Thoughts
A French Drain can be an extremely effective method for solving a drainage problem in your yard and maintaining the integrity of below grade concrete walls.
If you determine that a french drain is right for you, make sure to do your homework in terms of best practices for installation. Additionally, make sure to locate any utility lines or wiring that might be beneath the area that you will be digging your trench. The last thing you need is to add a broken pipe to your ever growing “to-do” list.
Hopefully you find this post useful and it can point you in the right direction in terms of addressing the drainage needs for your house.
Happy DIY’ing!