What do you put down before a retaining wall?

Author: Wilmer Wisoky  |  Last update: Tuesday, December 16, 2025

Fill the trench with about 3 inches of paver base, spread it with a rake and tamp it down. Tamping the base provides a strong foundation. When it's all level, you can begin installing the block. Wet the paver base if it's dry and dusty.

How do you prepare the ground for a retaining wall?

How to Build a Retaining Wall
  1. Step 1: Excavate your space. ...
  2. Step 2: Lay a substantial gravel base. ...
  3. Step 3: Compact the gravel with a large compactor. ...
  4. Step 4: Pinup filter fabric. ...
  5. Step 5: Install perforated pipe for water drainage. ...
  6. Step 6: Lay the first course of block and fill with gravel.

What do you put under a retaining wall?

To build a quality wall, use a clean, granular rock underneath the base course to create a firm foundation for your project. Good drainage and compaction will add to the quality and performance of your finished wall. We refer to the material used for the base, within and behind the block as Wall Rock.

What are the 7 common mistakes made when installing retaining wall blocks?

7 Common Mistakes To Avoid When Installing a Retaining Wall
  • Choosing the Wrong Material. ...
  • Not Providing Adequate Drainage. ...
  • Forgetting the Frost Line. ...
  • Too Much Weight Behind the Wall. ...
  • Inadequate Footing. ...
  • DIYing a Complicated Wall. ...
  • Not Maintaining Your Wall.

What foundation is needed for retaining wall?

Retaining wall foundation depth should be 300mm if the soil is firm and well-drained, or 450mm if less firm and unstable. Dig out foundation [base on which wall stands] which must be twice the width of the wall. WONKEE DONKEE says to use a 215mm Hollow Concrete Block with a 450mm width foundation.

Build a Block Retaining Wall - Build a Workshop#2

What base do you need for a retaining wall?

The trench you are going to build your retaining wall in should be wide, deep, and level. Size the trench so there's enough room for the block and at least 8 inches of space behind it. Excavate deep enough to completely bury at least one full course, including space for 6 to 8 inches of base material.

What is the foundation of a retaining wall called?

Footing. The concrete footing or pad that is used to bear the weight of a retaining wall. Foundation Soils. The portion of soils below the leveling pad and reinforced soil zone that distributes pressure of the retaining wall bearing weight.

Can you build a retaining wall without a footing?

In summary, retaining walls do need a footing to ensure they are structurally sound and have proper drainage to prevent cracking or collapse. Without a footing, the ground beneath the retaining wall can shift, which can cause the wall to shift as well, leading to cracking or collapse.

What is the thumb rule of retaining wall construction?

Rules of thumb commonly used by designers to establish the geometry of the wall include (refer to diagram): Base width = 1/2 to 1/3 of the height of the wall. Base thickness = 1/8 of the height of the wall but not less than 12 inches. Stem thickness = 6 inches + ¼ inch for each foot of wall height.

What is the most common retaining wall failure?

Soil saturation is the most common external factor that causes retaining wall failure, but there are many ways to prevent it.

What is the best base for a retaining wall?

Plan to backfill the wall with well-draining gravel or sand. Higher walls or areas with soil that stays wet may need a drainage pipe. Keep in mind that clay soil retains water and sandy soil drains too easily. You'll need a well-draining soil mix behind your landscape retaining walls.

Does a 2 foot retaining wall need drainage?

Absolutely! Even a 2-foot retaining wall needs an effective drainage system. Without it, water can build up behind the wall, leading to pressure that might cause the wall to lean or even collapse. All walls need systems to manage water effectively, preventing damage over time.

What is the cheapest type of retaining wall?

What is the cheapest type of retaining wall? Poured concrete is the cheapest type of retaining wall, in terms of materials. Pressure-treated pine is next, and wood retaining walls are becoming more popular now. If you prefer stone, granite is generally the least expensive option.

Can you build a retaining wall on fill dirt?

Dig A Trench To Outline The Space

Ensure the trench is wide enough to support both the retaining walls as well as any plants or flowers that will be added. Keep in mind that the fill dirt will act as a base for the entire feature, meaning any wall layers and plants should have a layer of fill dirt underneath it.

How deep should a retaining wall be buried?

Excavation

Dig a trench for the bottom row of blocks. They should be buried about 1 inch deep for every 8 inches of wall height. This provides strength and stability to your retaining wall. Make sure that your trench is level and compacted.

How to prep a base for a retaining wall?

Base Preparation
  1. To start your layout, place stakes to represent the location of the front of the retaining wall. ...
  2. Excavate the area by removing all surface vegetation and organic materials from the area. ...
  3. If reinforcement is needed excavate behind the wall to accommodate the design length of the geogrid.

How thick should a 4 ft retaining wall be?

Medium Walls (4 to 10 feet):

The thickness can vary between 12 and 18 inches, contingent upon slope and soil characteristics.

What is the local law 37 retaining wall?

RCNY §103-09 and Local Law 37/08, effective January 1, 2014, requires owners of properties with a retaining wall or part of a retaining wall which is at least ten feet high and faces a public right of way such as a sidewalk or entrance must have a condition assessment of this wall conducted every five years and the ...

What is the minimum base for a retaining wall?

2.7 Base Trench Requirements

Typical depth of the trench is based on a minimum 6 in s5 cm) deep compacted wall rock base and buried block depth equal to 1 in (2.5 cm) of depth per foot (30 cm) of wall height, with a typical minimum of 6 in (15 cm) for commercial projects.

What are the common mistakes for retaining walls?

To ensure your project goes smoothly, avoid these 5 common mistakes.
  • Ignoring Proper Drainage. One of the most critical aspects of retaining wall installation is ensuring proper drainage. ...
  • Skipping the Foundation. ...
  • Choosing the Wrong Materials. ...
  • Incorrect Wall Height. ...
  • Poor Backfilling Techniques.

Can I build a retaining wall on my property line?

With the permission of both property owners, a retaining wall can be built on property lines. But it's worth noting that the two parties still have responsibility for any of their actions that destabilises the wall's structural integrity.

Why put gravel behind a retaining wall?

This is why the drainage system and gravel backfill are crucial; they prevent water from becoming trapped and help maintain the wall's stability. Regardless of the style or material you choose, these components are the foundation of a long-lasting retaining wall system.

What are the three types of retaining walls?

Each type is designed to suit the specific needs of a project according to the site conditions. The four main types of retaining walls are gravity retaining walls, cantilever retaining walls, embedded retaining walls, and reinforced soil retaining walls.

What goes behind a retaining wall?

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.

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