Stagnant water on your property can destroy your landscaping and serve as a breeding ground for pests like mosquito larvae. It can also potentially flood your basement by leaking into the foundation of your house.
The French drain system can prevent water from getting near your house’s foundation. French drains improve drainage in your yard, but they require the proper size gravel to function properly.
This article will go over the various aspects that affect the ideal size of gravel for French drains, as well as the processes for installing them to solve drainage issues.
What is a French Drain?
A french drain is a gravel-filled trench with a slotted or perforated pipe. It’s also known as a curtain drain or a perimeter drain. These drains are designed to guide groundwater or surface water away from a particular spot and toward the lowest point where it can seep through the top layer of gravel and into the drain.
Additionally, French drains can stop water from accumulating and pooling in particular places which could otherwise result in water issues above or below ground. As an alternative, this water is sent to a more advantageous site, such as a dry well or a location of your choosing.
Design of French Drains
There are numerous aspects to consider when creating and installing a French drain. The factors to take into account include:
- Drainage component: Gravel can range in size from pea gravel to larger chunks of river rock. When different-sized aggregate is used, the smaller bits often sit closer to and on top of the surface, while the larger ones typically go closer to the pipe.
- Drainage depth: Water-diverting projects should be able to use depths between 8 inches and 2 feet. Those constructed around retaining wall bases, subsurface housing, and foundations may be deeper.
- The flow of the drain: The slope, aggregate placement, and fabric around the pipe to stop debris from clogging it are all important factors in ensuring that water flows freely.
- Length of the drain pipe: The pipe should have adequate length to transport water from the subsurface locations where it gathers to the point where it emerges.
The French Drain Installation
Choose an Exit
The first step in creating a French drain is selecting an exit point. Do you wish to remove impurities from the water before it reaches the waterways or collects them for later use?
Choose the Ideal Spot
The ideal site is determined by the issues’ location, the elevation in the area, and the soil quality. Use the above design advice to assist in identifying the optimum slope and depth.
Get Ready to Dig the French Drain
Be mindful of the local ordinances and consider how your drainage solution may affect your neighbors. It’s also a good idea to do this now so that any subsurface utilities may be designated before digging can start.
Dig a Trench
The most labor-intensive part of the project is digging the trench. The trench for French drains needs to be 9 to 12 inches broad and at least 18 inches deep at its shallowest point.
Use Landscape Cloth to Line the Trench
Dig the trench, line it with landscaping fabric, and then fill it with gravel. This material encourages water percolation while preventing dirt from contaminating the gravel. A small amount of gravel is then shoveled over the fabric once it has been laid down, allowing the corners to wrap around the gravel and hold it in place.
Add a Pipe
At the bottom of the trench, install a perforated pipe pointed toward an exit to drain away from the house.
Fill with Gravel
The gravel of your choosing will now be shoveled in. Your layer needs to be about three inches thick. Once the gravel is in place, cover it with a further layer of landscaping fabric, topsoil, and fresh sod.
How to Select the Best Gravel for a French Drain
Round gravel is used to fill the trench, and a pipe with holes has been added to allow water to readily flow away from the home. One of the most important parts of the French drain is the gravel because it enables water that has seeped through the ground to be taken away down the slope of the drain. But which gravel is ideal for a French drain?
Hard rocks like washed river rock or granite chips are the ideal gravel for French drains. The gravel pieces should ideally average at least 1′′ wide to provide the best permeability for water to run along. If you use a perforated pipe, the gravel layer at the bottom of the trench should fill up about one-third of the way.
Purchase even larger gravel pieces if your arrangement does not contain a pipe. Get stones that are at least 1 1/2′′ in size, and cover the trench with gravel until it’s two-thirds full. This gravel layer will act as the main canal to keep water from accumulating in your yard.
To prevent premature deterioration, a tougher rock should be selected for your base gravel. Pea-sized gravel may be attractive, but draining cannot be accomplished with it. Similarly, smaller rocks don’t let enough water flow through them.
Finally, ensure the gravel you’re using is the washed variety to avoid dust from delaying water flow. Examine the stones before adding more gravel to the trench.
The integrity of concrete walls can be preserved while resolving a drainage issue in your yard using a French drain. If you decide to use them, be sure to conduct your research on installation best practices. Locate any utility or wiring lines that may be under the site where you will also be constructing your trench.
If you are experiencing drainage issues and water accumulating in your yard, call the professionals in your area. At Granite Foundation Repair, we have experts who will examine your yard and recommend the best drainage systems to safeguard your home’s foundation.