Tip #3: Place French drain below the frost line. A properly installed French drain will begin at the depth of the base of the perimeter beam and is installed with a 1% minimum slope (1 inch in 8 feet). This is usually below the
In cold climates, a French drain should be installed below the frost line to prevent freezing, which typically means at least 4-6 feet deep, depending on the region.
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.
A French drain needs to be surrounded by gravel in order to filter out silt and prevent clogging the drain pipe.
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.
Tip #3: Place French drain below the frost line.
Generally, those placed below the frost line tend to provide year-round performance, especially in cold regions. They work in all seasons and usually don't suffer from issues such as frozen obstructions caused by the freeze-thaw cycle.
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.
Line the Drain With Membrane to Minimise Blockage
Once your French drain is installed, maintenance is essential. Don't let it get blocked or you could end up with a moat around your building: great if you're looking to protect it from invaders – and not so great if you're trying to fight damp.
The line varies by latitude, it is deeper closer to the poles. The maximum frost depth observed in the contiguous United States ranges from 0 to 8 feet (2.4 m). Below that depth, the temperature varies, but is always above 0 °C (32 °F).
The IPC and IRC also state that all water and sewer lines must be at least 6 inches below the typical frost level for the area to help ensure that the pipe can't freeze.
Install a Heat Cable
For truly vulnerable plumbing pipes, you can install heat cables to keep them safe in the winter weather. Most heat cables have a built-in thermostat that can sense the thermostat pipe temperature and turn the heat off and on as necessary to prevent pipe freezing.
In summary, underground PVC pipes are indeed likely to freeze in cold environments, especially when buried too shallowly, the soil is moist, or the outside temperature is too low.
Always vent downspouts at the house to keep buried downspouts from freezing. You can get warm water through that vent in the wintertime if you have a freeze up. Then, if you do freeze up and you have a thaw, the water will come out of these vents.
Dig a trench from the place in your yard that needs drainage to your chosen outlet. Check for underground utility lines and pipes before digging. The trench should be about 18 inches deep and 9 to 12 inches wide.
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.
You may want to opt for rigid PVC which is less likely to clog, and make sure your gutter drains are at least 12 inches deep or more to avoid damage from freezing and heavy traffic. To keep water away from your foundation, create a gutter drain that is at least 4 to 6 feet long, as well.
Permits Needed to Install a French Drain
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. Major projects that warrant your French drain to discharge into a municipal sewer or roadside ditch, however, do require one.
Typically, French drains are 18 to 24 inches deep, but they can be as shallow as 8 inches deep. However, they can be deeper if you live in an area with heavy rainfall and high water tables.
While corrugated pipes have their place in some applications, PVC is the sound solution for a French pipe installation. At Align Foundation Repair, this is our go-to material for underground drainage systems.
Gravel trenches are narrow, stone-filled channels situated over well-draining soil that utilize the empty spaces between stones to act as a temporary reservoir for stormwater as it soaks into the surrounding soil.
Generally speaking, a French drain will last approximately 30 to 40 years. However, the above-mentioned factors may shorten its life cycle and it must then be replaced by a team of foundation experts.