How do I build 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.

Do retaining walls have weep holes?

Weep holes allow water to escape from behind the wall. These holes should be regularly spaced in the horizontal direction. Retaining walls with a height greater than a few feet should also have weep holes that are regularly spaced in the vertical direction, forming a grid pattern.

What is a French drain and what does it do?

A French drain is a trench filled with a perforated pipe and gravel that allows water to drain naturally from your yard. Depending on the size of your yard and the scale of your drainage issue, you can purchase the pipes and equipment to create a French drain yourself.

How does a retaining wall drain work?

Retaining wall drainage is critical. It ensures water does not collect behind the wall, causing it to fail. A quality drainage system collects and redirects rainwater away from the wall. It decreases pressure on the soil around the foundation and within the wall itself, reducing erosion and settlement.

How deep do you have to dig for a French drain?

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.

Where should drainage pipe be retaining wall?

Pipe drains or agricultural drainage pipe should be at the base of the wall with perforations to direct water away from behind the wall and out through weep holes. To maximise retaining wall drainage, the pipe should extend to the entire length of the wall and be vented at regular intervals.

How do you put weep holes in a retaining wall?

For walls built out of cinder blocks, line the weep holes up with the grout lines to ensure rebar is avoided. Use a core drill* to core 2″ diameter holes in the locations that you have marked. To penetrate the full thickness of the retaining wall, use a wet concrete diamond drill bit*.

How many weep holes do I need?

Installation Sitework. Vents are required at 450mm intervals and each opening should have at least 2 weep holes.

Can you backfill a retaining wall with dirt?

Second, a retaining wall must have properly compacted backfill. Backfill refers to the dirt behind the wall. In order to provide proper drainage, at least 12 inches of granular backfill (gravel or a similar aggregate) should be installed directly behind the wall.

Should you use fabric behind retaining wall?

You should use landscape fabric behind a retaining wall because the fabric supports the bricks, wood, or other materials that make the wall. Wet soil can push against a retaining wall, weakening it. By placing a strip of landscape fabric under the soil, the wall won’t have as much pressure on it.

How many drainage holes do I need for a retaining wall?

For large walls, around 6 ft. or taller, incorporate 3- to 4-in. dia. weep holes every 3 to 4 feet. If your wall is smaller than that, make your holes more like 1-1/2 in.