Readers ask: How To Install Drainage Behind A Retaining Wall?

Do you have to put drainage behind a retaining wall?

Drainage. Third, since most retaining walls are impervious, which means water cannot pass through the wall itself, efficient drainage is crucial. When drainage goes unaddressed hydrostatic pressure will build up behind the wall and cause damage such as bulging or cracking.

How deep should a French drain be behind a retaining wall?

And make it about 18 to 24 inches deep; the depth will vary depending on the depth of your soggy area. If your French drain is against a foundation or retaining wall, you’ll need to dig just below the footing.

What is the best base for a retaining wall?

Due to soil erosion, your retaining wall should be built on a solid foundation made from gravel.

  • Choose gravel that has stones sized between 1/2-inch and 3/4-inch.
  • Fill the trench with a 2- to 3-inch layer of gravel.
  • Use a rake to ensure the stones are evenly distributed.

What kind of stone do you put behind a retaining wall?

Crushed or smooth stone, well graded, compactable aggregate, ranging in size from 0.25 in. to 1.5 in. (6 to 38 mm) is the ideal wall rock size.

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What is the cheapest type of retaining wall?

What is the cheapest retaining wall material?

  • Treated pine and is the least expensive material.
  • Hardwood is more expensive than treated pine.
  • Railway sleepers are another – slightly more expensive – option and are built to withstand ground and water contact.
  • Concrete sleepers are more expensive.

Can you use pea gravel behind retaining wall?

Base material



The various-sized crushed gravel with the fines helps ensure the right amount of compaction. Round rocks, such as pea gravel, roll and dislodge under pressure resulting in failure of the retaining wall. Lay a 4- to 6-inch layer of the crushed base material in the trench.

What is the easiest retaining wall to build?

For the average do-it-yourselfer, building a retaining wall is easiest when using masonry blocks that will be stacked no taller than three feet, with no mortar binding the stones or concrete members. (For a curved wall, mark instead with a garden hose or spray paint.)

How do you make a strong retaining wall?

Here are three key principles in building any solid retaining wall:

  1. Bury the bottom course, or courses, of the retaining wall one tenth the height of the wall to prevent the soil behind from pushing the bottom out.
  2. Step back the blocks, rocks or timbers to get gravity working in your favor.

Is crushed gravel good for drainage?

Crushed stone is great in paving blocks and concrete for sidewalks. If you have an area of your yard where the water doesn’t drain the way you would like, add some crushed stone as a decorative feature. The stone will help the water drain and not puddle while providing some decoration.

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What size gravel is best for drainage?

In general, you want to aim for ½ inch to 1-inch gravel for drainage. Areas that will see especially heavy flow may need larger gravel. Or, projects without drainage pipes may also need larger gravel. For example, a French drain without perforated pipe needs 1 ½ inch gravel.

How high can a retaining wall be without a permit?

Legislation on the construction of retaining walls is set by your local council. The ‘magic number’of 1 metre is commonly referred to as the maximum height you can build to without a permit.

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