Retaining walls are a regular part of landscaping used to support the soil and prevent erosion in sloping ground. You can convert an unsuitable slope to a usable tiered garden or a level area on which to place a patio. When landscaping, a consideration in the thoughts of many homeowners is whether or not to include a concrete footing. The answer is not a simple yes or no; it is a question of a number of important considerations, and we can help you make informed decisions at Bill’s Custom Concrete & Yard Drainage. 

The Significance of a Strong Foundation 

A retaining wall will need to be strong enough to support immense pressure from the soil behind it, pressure that is increased by water and elevation. A footing is part of the foundation of the wall, spreading its load to a larger surface area so it won’t shift, settle, or collapse. 

For most retaining walls, and particularly for high retaining walls, a solid footing for a concrete wall is not just the way to go – it’s required for permanent stability and security. A wall with a defective base is far more likely to collapse, leading to expensive repairs and possibly harm to your property.

Determinants of the Need for a Footing 

There are various considerations that decide whether you require a concrete footing for a retaining wall construction.

Wall Height 

The crucial factor involved here is the height of the wall. A small ornamental garden wall less than two feet high won’t need a deep concrete footing. Walls three or four feet or higher, though, are retaining a lot of ground and absolutely need to be supported by a solidly constructed, engineered foundation to keep on standing. Wondering, do I need a concrete footing for a retaining wall​? If your wall is tall, the answer is likely yes.

Soil Conditions 

The type of soil on the ground is significant. Loose/soft clays or sand soils do not hold and settle readily. In this case, you will have to place a footing for a concrete wall to create a solid base. Solid bedrock or dense draining soil is solid enough to hold a small-sized wall without a concrete foundation.

Water and Drainage 

Water is the worst nemesis of the retaining wall. Lack of drainage will result in hydrostatic pressure on the back face of the wall that will exert effect upon it. Areas or sites of increased water tables or rainfalls need a deep foundation, usually a footing made of concrete, to support this thrust and maintain the position of the wall. Knowing the proper retaining wall footing depth is essential for tackling water issues effectively.

Local Building Codes 

Check local building ordinances before building. Every city will have a list of ordinances that will pertain to retaining walls, and it will typically consist of engineered drawings and concrete footings on walls four to three feet and above. If these requirements are not satisfied, there will be fines and the removal and reconstruction of the wall accordingly.

How Deep Does a Retaining Wall Footing Need to Be in Oklahoma City?

In Oklahoma City, local building code sets the frost line at 18 inches, meaning any footing that needs frost protection has to sit at or below that depth. Most residential retaining wall footings in the OKC metro end up excavated to at least 18 to 24 inches, both to clear the frost line and to reach undisturbed, stable soil rather than loose fill or topsoil. Taller walls or those on soft or expansive soil often need to go deeper still, since the footing has to bear on solid ground, not just clear the frost line.

This is one area where a generic rule of thumb from a different state’s building code can lead homeowners astray. Frost depths vary widely by region, and a footing sized for a colder northern state is overbuilt for Oklahoma, while a footing sized for a warmer, frost-free climate would leave an OKC wall vulnerable to heave. A local concrete contractor will excavate to the depth your specific soil and wall height require.

How Wide Should a Retaining Wall Footing Be?

Footing depth gets most of the attention, but width is what actually keeps a wall from tipping forward or sliding under soil pressure. As a general rule, footing width should measure at least twice the thickness of the wall itself, and for taller or gravity-style walls, a base width equal to roughly one-third to one-half of the total wall height is a common benchmark. A 4-foot-tall wall, for example, may need a footing in the range of 16 to 24 inches wide.

Wider footings distribute the wall’s weight and the pressure from the retained soil over a larger area of ground, reducing the bearing pressure at any single point. Skimping on width is a common mistake in DIY retaining wall projects and one of the more frequent reasons a wall leans or fails within a few years of installation.

Does a Retaining Wall Footing Need Rebar?

Yes, in nearly all cases. A footing without reinforcement can crack under the same soil pressure it is meant to resist, and once a footing cracks, the wall above it loses the uniform support it needs to stay in place. Most retaining wall footings use horizontal rebar running the length of the footing, tied to vertical rebar that extends up into the wall itself to lock the wall and footing together as one structural unit.

For a full breakdown of rebar sizing, spacing, and how deep the steel should sit inside the concrete, see our guide on what rebar size is used in residential concrete construction.

Alternatives to Concrete Footings 

Although a concrete retaining wall in Oklahoma City is a popular option for larger walls, there exist additional materials that are applied on small walls that blend into the surroundings.

Compacted Gravel Base 

For low walls, a solidly compacted base course of gravel will generally suffice. This involves excavating the hole to the appropriate depth and bedding it down with a layer or two of crushed stone a few inches thick, and compaction down to a solid level base. This provides ideal drainage, again holding down pressure behind the wall to a minimum.

Geo-Grid Reinforcement 

Geo-grid is a stabilizing man-made reinforcement grid that underlies the earth stabilizing behind the wall, reinforced even more. It is spread out in courses between courses of wall blocks and down into the ground. 

Although typically spread on a gravel base, it provides excellent added reinforcement and can replace a large concrete footing on select projects. Want to know how to build a concrete footing for a retaining wall​? Start by ensuring the foundation is properly prepared with gravel and reinforcement like geo-grid.

How to Construct a Long-Lasting Wall 

Whether to put a concrete footing on the retaining wall or not will be based on the height of the wall, the type of ground, the problem of drainage, and local building ordinances. Although low walls used just to decorate may be supported when a properly compacted gravel base is used, larger and taller walls basically always should come with a concrete footing to be stable and long-lasting. Contact Bill’s Custom Concrete & Yard Drainage for tailored advice for your project! 

Frequently Asked Questions

How Deep Should a Retaining Wall Footing Be?
 In Oklahoma City, footings typically need to reach at least 18 inches to clear the local frost line, with many walls excavated to 18 to 24 inches to also reach stable, undisturbed soil. Taller walls or soft soil conditions can require greater depth.

Do Small Retaining Walls Need a Footing?
Walls under about two feet tall often get by with a compacted gravel base instead of a poured concrete footing, especially in stable soil. Walls three feet or taller generally need a footing to meet local building code and stay stable long term.

How Wide Should a Retaining Wall Footing Be?
A common guideline is a footing width of at least twice the wall’s thickness, or roughly one-third to one-half of the total wall height for taller gravity walls. Wider footings spread the load and reduce the risk of tipping or sliding.

Does a Retaining Wall Footing Need Rebar?
Yes, in almost every case. Rebar ties the footing and wall together and keeps the concrete from cracking under the constant pressure of the retained soil.

Can I Build a Retaining Wall Without a Footing?
Small decorative walls under two feet in stable soil can sometimes be built on a compacted gravel base without a poured footing. Walls above that height, or those on soft or wet soil, need a proper footing to meet code and avoid failure.

Does Oklahoma City Require a Permit for a Retaining Wall?
Many jurisdictions in the OKC metro require a permit and engineered drawings for retaining walls above a certain height, often three to four feet. Check with your local building department before starting the project.