Masonry retaining walls: costs and permits

Retaining walls can level or terrace a slope, keep the grade around a tree or hold up a level area such as a patio or driveway.² Most fail because of pressure from water or soil moisture building up behind them, so every wall should let that water drain down and away through gravel backfill or drainage blankets and drain pipes. Structural walls need weep holes. The wall should sit on sound, compacted base material reaching at least a foot past its front and back, and it's more stable leaning back into the slope it holds.³

HUD's inspection guide says a retaining wall more than 2 feet high should be backed with drainage material such as gravel, with drains at the bottom that let water out at the end of the wall or through pipes set in it. In all but the driest climates, poor drainage behind a retaining wall can make it fail.¹

HUD's guide lists what to look for:¹

• Bulges and cracks. A bulge from top to bottom (bowing) or along the wall (sweeping) can come from water pressure or a wall too weak for the earth behind it. Caught early, and where poor drainage is the cause, it may be fixable.
• Leaning or sliding. This can mean the wall isn't strong enough. Water behind it can add to sliding, especially in clay soil.
• Settling and heaving. Fill under a wall can compact, wet soil can dry out and settle, and in cold climates poor drainage can lead to heaving from frozen ground.
• Drains that stay dry. Check the weep holes and drains after a heavy rain. If they aren't letting water out, clean them and look again next rain. If that fails, the fix is digging out behind the wall, replacing the drainage material and damaged pipe, and backfilling.

Patching a crack won't stop a wall that's moving. HUD says a failing retaining wall more than 2 feet high should be inspected by a structural engineer, and significant failure usually means rebuilding or replacing all or part of it.¹

Port Townsend in Washington quotes the model residential code's rule: a retaining wall up to 4 feet tall, measured from the bottom of the footing to the top of the wall, needs no building permit unless it supports a surcharge. A surcharge is sideways force from something near the top, such as a building, a tank or a parking area, or from ground sloping up behind it. There, a wall that supports one needs an engineered design and a permit at any height.⁴ Douglas County in Colorado uses the same 4 feet, and also wants a permit and an engineered design for terraced walls set closer together than twice the lower wall's height.⁵

Some places are stricter. Prince William County in Virginia needs a permit once a wall's exposed height is over 3 feet, and an engineer for one of 24 inches or more with a surcharge or problem soil.⁶ Notice that height is measured differently from place to place: from the bottom of the footing, from grade or by exposed height.

Some states set a height in their own building code or rules. Unless noted, a wall at or under it needs no permit if it doesn't support a surcharge. In Minnesota, New Mexico and Virginia, a wall that holds back Class I, II or III-A liquids isn't exempt either:

• Connecticut: 3 feet, from finished grade at the bottom of the wall to finished grade at the top.⁷
• Maine: 4 feet, from finish grade, and a permit is needed only where a municipal ordinance requires one.⁸
• Minnesota: 4 feet, from the bottom of the footing.⁹
• New Jersey: a permit is needed for a wall, or walls on the same slope, with a total height of 4 feet or more, measured from the bottom of the footing, or for a shorter wall that has a negative impact on a foundation.¹⁰
• New Mexico: holding back less than 36 inches of unbalanced fill, and no more than 6 feet from the top of the wall to the bottom of the footing.¹¹
• Ohio: 4 feet, from the bottom of the footing.¹²
• Pennsylvania: 4 feet, from the lowest level of grade.¹³
• Rhode Island: 32 inches, from the lower finished grade, though a cast-in-place concrete wall over 24 inches needs one.¹⁴
• Utah: holding back less than 4 feet of unbalanced fill, unless the code requires the wall to be designed under its section R404.4.¹⁵
• Virginia: holding back less than 3 feet of unbalanced fill.¹⁶

In other states, ask your city or county building department before work starts. Your state's rules page on this site has its permit rules, with their sources.

Pick your state's rules page

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These are published national ranges from cost guides. They aren't quotes.

A wall's height, its face and whether it needs an engineer's design all change the job, so have yours priced as it'll be built.

• Who pulls the permit, if one's needed, and who books the inspections.
• How tall the wall is, measured the way your building department measures it.
• How water gets out: the gravel behind the wall, the drain pipe at its base, where it lets out and whether there are weep holes.
• How deep the footing or base goes, and what it sits on.
• Whether a driveway, building or rising ground near the top adds load, and who provides the engineer's design if your city or county wants one.
• Who'll call 811 to have buried lines marked before digging. Prince William County tells owners to call before excavating, says the service is free and holds anyone who skips it liable for damage.⁶

Before you hire, how to check a masonry contractor has what to look up. If you'd like to hear from masonry contractors near you, you can send a request through the request form.