It’s not always simple to determine how high construction on your land may be. You can do certain things yourself, yet more substantial construction requires a structural engineer and many building permits.
One thing that could be tricky to fathom is how high can a retaining wall be. Retaining wall construction isn’t like a regular building with upper or lower floors, yet many retaining wall designs are load bearing, such as tiered retaining walls.
Do you need to build such a retaining wall and are unsure if you can build it yourself, or do you face permit requirements? How high can you build a retaining wall? Any retaining wall can rise more than ten feet, yet many walls are over three feet, and many municipalities require a permit to allow them to be constructed.
In our guide, you can learn more about building a retaining wall without a permit and how large it could be. By the end, you’ll see many measurements needed to determine the size of your structure, which can affect your retaining wall height
without a permit. (Learn How To Build A Brick BBQ With Chimney)
What Types of Retaining Walls Are There?
In residential and commercial landscaping, retaining walls are typical. Retaining walls alter a property’s landscape physically besides preventing soil erosion. The four retaining walls most frequently are:
Cantilevered Retaining Wall:
Many applications use the most popular retaining wall style for medium to large heights.
They are often made of concrete, with the wall (stem) connected to a concrete footing that supports the weight of the soil and prevents the structure from toppling. For ultimate strength, a steel rebar is used to reinforce these walls.
Gravity Retaining Wall:
These are suitable for short landscaping walls since they rely on their mass to withstand pressure from behind. Gravity retaining walls are the simplest because they have the most material variety available.
Sheet Piling Retaining Wall:
Walls used in confined locations and soft soil can be driven directly into the ground.
Such walls are made of steel, wood, or vinyl, placed 2/3 below ground and the upper 1/3 top of the wall outside the ground. To offer more reinforcement, they are constructed with vertical corrugations.
Anchored Retaining Wall:
They are used frequently in situations with projected higher loads or for fundamentally thinner walls.
Anchors may support a variety of “fronts” of retaining walls pushed deep into the ground and attached by cables or strips using this wall.
Any other approaches can be combined with this one as additional support. However, such a design would be out of DIY’s scope and need a professional engineer.
How Tall Should A Retaining Wall Be?
Broadly speaking, there’s little need to construct your retaining wall any higher than three to four feet.
Building taller walls over four feet requires city approval and pricy engineering, particularly in some towns or geographical areas. In addition, think if your retaining wall is to prevent soil erosion or to direct water and avoid floods in extreme weather.
The retaining wall starts from the bottom of the first block or bottom of the footing, contrary to the common misconception that you only think about the height measurement of what you can see on your retaining wall.
For instance, a retaining wall with an exposed height of less than 3.5 feet will typically have at least 6 inches of hidden wall, thus totaling a wall height of 4 feet.
For cantilever or segmental gravity (block) retaining walls, a building permit is typically necessary if the total height measured from the bottom of the footing to the top exceeds 4 feet (including any buried sections).
Even though there is no premium, some towns demand a building permit for walls taller than two feet.
For wall heights between 4 and 6 feet, some areas issue a building permit without an engineer’s signature, so either way, you’ll need to check your local codes before you build.
Besides this, you can find limitations set by block manufacturers. For example, the maximum height for a particular block system can typically range from 2 to 6 feet.
You should never build above the height advised by the manufacturer, so consult the block manufacturer or expert to confirm the maximum height of any blocks used for walls taller than 2 feet. (Learn How To Turn Off Fire Alarm In Building)
How Tall Can Retaining Walls Be Without Permit?
As a general rule, most cities require a permit if measured from the bottom of the footing to the top of the wall, and it’s taller than 3 to 4 feet. These regulations vary depending on where you live and the type of property your wall is on.
For example, if you live in a Phoenix location, and wish to build a retaining wall taller than 3 feet, generally, you need a permit.
Any object exerting a lateral force on top of the wall is known as a surcharge. Any wall surcharge needs engineer approval.
This includes vehicles, a pool, equipment, footings, or a fence on the wall; even if not tied to the wall, such a fence adds wind load.
Trees create a surcharge behind a wall as they grow and gain weight, their roots push the wall out, and their height imposes wind stresses on the wall. Behind the wall, you can grow small shrubs and plants.
The edge of any surcharge object shall be at least 2 times the total wall height from the back of the retaining wall.
If your total wall height is 4 feet, including the buried height plus exposed height, any surcharge must be at least 8 feet from the back of your wall blocks.
The grade or slo0ping fill behind your wall project also adds lateral stress.
Slopes or the garden grade are shown by the horizontal (H) length for every 1-ft vertical (V) elevation.
A 10H:1V slope rises 1 ft in height for every 10 feet of horizontal distance.
Any wall slope needs project engineer approval. Even if the slope is a fair distance from the wall, it should not exceed 2H:1V, as a sloping wall must be considered.
The type of permit necessary for a retaining wall varies on its size, the city’s zoning rules, environmental implications, and the structure’s type.
Most cities have zoning restrictions regulating wall size and length depending on home and property lines. (Learn How To Build A Rock Drainage Ditch)
What Will The Required Width Of A Retaining Wall Be?
Engineers say a retaining wall should be 1/2 to 1/3 the structure’s height. If your wall is too tall for its base, it may collapse in inclement weather.
So, a 3-foot-tall retaining wall must be at least 12 inches wide.
A terraced wall uses two or more lesser walls instead of a single taller wall.
Unless the upper wall is offset (D) 2 times the lower wall height, the upper tiered wall forces a surcharge on the lower wall, therefore they are treated as one wall (H1).
H2 must be less than H1 (H1).
Two 3-ft-tall, 4-ft-apart tiered walls are treated as one 6-ft-tall wall and require a permit and an engineer.
If the two 3-ft-tall tiered walls are 6-ft apart or more, they can be treated as independent walls.
On a non-engineered wall, only one terrace is allowed. Many landscapers develop multiple layers to avoid permits and engineering expenditures. This is a ruse landscapers employ to undercut their competition. An unengineered wall can fail with the first rainstorm.
How Tall Can Wood Retaining Walls Be?
Wood retaining walls should be 4 feet tall. Most localities have a 3-to-4-foot height limit for unpermitted buildings, including retaining walls.
A wood retaining wall taller than four feet would need extra support, which might be costly. Contact your city regarding code codes if your home needs a taller wall.
What if There Is Water Near My Wall?
Hire an engineer if your wall is erected near a pond, creek, or other water sources. For example, leaking irrigation lines, water mains, or other pressured water sources might cause soil and wall structure problems.
To provide a safe wall and stop soil erosion, numerous additional precautions must be taken because water is the leading cause of retaining wall failures.
Consider moving or piping downspouts away from your wall while planning your location.
Water should never drain toward a wall (negative grade).
Behind the wall, water shouldn’t pool. Call an engineer if water can’t be diverted off the wall. Also, contact an engineer if your wall site has groundwater or moist soil. This post discusses drainage.
How Close Can A Fence Be To A Retaining Wall?
Try to create a retaining wall three feet away from an existing fence. According to the International Building Code, non-engineered retaining walls must be 3 feet from fencing.
Because fencing creates a surcharge, it can magnify storm winds and demolish your retaining wall.
How Close To A Property Line Can I Build A Retaining Wall?
In most area codes, you can build a retaining wall within a foot of your property line. However, if an exact border hasn’t been drawn, you may require approval from your neighbors or the city with a building permit.
Can I Build A Retaining Wall Close To A Structure?
Distance-wise, any retaining wall should be 2 to three feet from any structures. For example, offering a gap for your wall provides drainage and chances of wall failure in a storm.
To prevent floods, place landscape cloth behind your retaining wall.
What Material Is Best For A Retaining Wall?
Material-wise poured concrete, brick, and stone materials are options for your retaining wall. Of the three, poured concrete gives your wall the most design options while being strong.
Regardless, building a retaining wall from concrete is generally recommended to line any retaining wall with landscaping fabric and add gravel or stone materials to drain water. (Learn How Many Rockets For Sheet Metal Wall)
What Are The Height Limits for Retaining Walls?
Here is an overview of wall height limits. However, regardless of the materials used, such as concrete or blocks, check with your city as regulations can vary from city to city, and you’ll know for sure if you need a building permit.
- Retaining walls less than or equal to 30 inches tall are automatically allowed.
- According to Chapter 11.5.20: Development Permits, a retaining wall taller than 30 inches and no taller than 48 inches is allowed. In addition, a landscaping buffer at least 18 inches wide must be placed in front of such a wall if it fronts a public street or wall.
- According to Chapter 11.5.20: Development Permits, retaining walls taller than 48 inches are allowed with a conditional use permit.
- As required by the California Building Code, a guard rail must be installed on a retaining wall.
- If the aggregate height of the retaining wall plus the fence, wall, hedge, or screen planting does not exceed 10 feet, then a fence, wall, hedge, or screen planting may be built on top of the retaining wall.
- A landscaping terrace of at least 3 feet in width must divide a fence from a retaining wall if its combined height exceeds 6 feet.
- If a setback area has several retaining walls, they must be separated by at least three feet of expansive landscaped terraces.