Can you put a French drain under a retaining wall? If you're building a retaining wall, add a French drain behind the first course of stones or blocks. Otherwise, water moving down the hill will build up behind the wall and undermine it. The pipe should rest on the same compacted gravel base or concrete footing that supports the wall.
How deep should a French drain be behind a retaining wall?
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.
How do you install a French drain in a retaining wall?
How do I run drainage behind a retaining wall?
For proper drainage, the first 12 inches of space behind a retaining wall should be filled with crushed stone or gravel. This is so that when water gets into the space, it does not become bogged down in soil but instead can flow down the wall to the drains or weep holes.
Where do weep holes go in a retaining wall?
There are several ways to prevent water from building up behind a retaining wall. Weep holes should be drilled through the wall. Weep holes allow water to escape from behind the wall. These holes should be regularly spaced in the horizontal direction.
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Do French drain holes go up or down?
So, when installing a French drain, the holes in PVC piping always face the upward position. The only time holes should be in the downward position is when installing a leaching field. This is when water is poured or pumped into a pipe and we want the water to drain out of the pipe into the surrounding ground.
How do you build a French drain?
Are French drains worth it?
French drain systems are incredibly effective because, unlike typical surface drains, they collect water over the entire length of the drain as opposed to one dedicated area. The force of gravity helps to guide water along a reliably smooth path to a desired discharge point.
Does a French drain have to have an outlet?
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.
How far apart should french drains be?
We recommend installing the french drains between 2 and 5 feet away from the foundation. There are a few variables that impact the exact distance to dig the new drain lines to carry water away from your home. Finding the right distance: Check where water is pooling naturally during heavy rains.
Can you put topsoil over French drain?
The simplest drain is a classic French drain, which is nothing more than a trench filled with coarse stone or gravel. The drain can be left open or, if aesthetics are a concern, can be covered with a couple of inches of topsoil and sod.
What can I put on top of a French drain?
Some use landscaping stones on the very bottom of the drain, serving as a first layer of rocks, then placing gravel on top. Along with this, you can use decorative landscaping stones to place on top of your French drain after you are done installing.
Can you add drainage to an existing retaining wall?
Installing drain lines at existing walls requires labor and equipment to remove the retained soil so the line can be correctly placed. Installing drains in an existing concrete block or wooden timber wall is done by boring weep holes and installing sleeves made from PVC pipe.
Can you drill your own weep holes?
DO NOT power up your drill. Drilling weep holes in the proper location is almost impossible because you don't know the actual termination point of the flashing. If you drill weep holes in the wrong places, you could introduce water penetration, damage mortar, or open the wall to pests.
Should I use solid or perforated drain pipe?
If absorption and drainage are required, perforated pipe should be used. If pipe serves only to move water away from an area (such as downspout run-offs, etc.), non-perforated pipe is best because it will not dissipate water into the surrounding area.