By Hometown Landscape

Our shop sits on Sandy Spring Road in Burtonsville, in the eastern corner of Montgomery County. Howard County starts just to the north. Prince George’s County starts just to the east. So when a homeowner asks us whether a new wall needs a Montgomery County retaining wall permit, our first question back is simple: which county is your yard in? In Montgomery County, a wall needs a building permit once it holds back more than 3 feet of soil. But height is only one of five triggers. A wall that looks short can still need a permit. And the height you see above the lawn is not always the height the county counts.

The Montgomery County rule, in plain words

Montgomery County’s Department of Permitting Services, called DPS, handles retaining wall permits. Its office is at 2425 Reedie Drive in Wheaton. DPS says you need a permit to build a retaining wall if any one of these is true:

• The wall holds back more than 3 feet (36 inches) of soil.
• The wall supports a surcharge load. We explain that below, because it catches a lot of people.
• The wall crosses a lot line.
• The wall sits in problem soils.
• The wall is part of a tiered system of two or more stacked walls.

Notice the word “or.” You only need one of the five. A wall that is 2 feet tall can still need a permit if it checks any other box.

You may also see a flat 4-foot cutoff quoted in older write-ups. The county’s current guideline for residential retaining walls, updated in February 2025, uses the 3-foot rule plus the four other triggers. When we plan a wall, we follow the current county rule.

Problem soils have a county definition too. It includes soil with a high water table, soil that swells or shifts, soil that compresses, soil that cannot carry much weight, and soil with frost heave potential. If you are not sure what is under your yard, that is worth asking about before any wall goes in.

What “retained height” means, and why the wall you see can fool you

The county measures retained height as the difference in grade between the two sides of the wall at the same spot. In plain terms, it is how much higher the soil is on the high side than on the low side. It is not the number of blocks you can count. It is not the height of the cap above the lawn.

That matters in two ways. First, many block walls start with a base row set below the lawn on the low side. That buried row sits below grade on both sides, so it does not add to retained height. Second, the ground behind a wall often keeps rising up a slope. When it does, the wall is holding back more than its face shows. Sloping soil behind a wall is also a surcharge, which is a trigger on its own.

Height brings a safety rule, too. Under the building code Montgomery County uses, a retaining wall needs a guard, such as a railing or a fence, when the drop from one side to the other is more than 30 inches and the high side is within 2 feet of a walkway, path, parking area, or driveway. So a wall along the top of a driveway can need a guard even when it is close to the permit line.

The surcharge trap: when a short wall still needs a permit

A surcharge is extra weight pressing down on the soil behind the wall. That weight pushes the wall outward, on top of the normal push from the soil. DPS gives three examples:

• Soil that slopes up behind the wall.
• The footings of a structure, such as a shed, a deck, or a house, resting on the soil the wall holds back.
• Cars or trucks on the soil the wall holds back, like a driveway or parking pad at the top of the wall.

This is the part most homeowners do not expect. A 30-inch wall that holds up the edge of a driveway needs a permit in Montgomery County. So does a short wall at the bottom of a hill.

The same goes for stacked walls. Some people try to skip the permit by splitting one tall wall into two short walls with a planting step between them. The county calls that a tiered retaining wall system, which it defines as two or more stacked walls with each higher wall set back from the one below. A tiered system needs a permit no matter how short each wall is.

Walls on the property line have their own steps. If the wall sits on the line, the permit application must include a letter of approval from your neighbor. Any part of a wall that crosses the lot line needs its own permit. And the county will not permit a retaining wall inside the County right of way.

When a wall needs a design professional

Needing a permit and needing an engineer are two different questions. DPS publishes a guideline for simple residential walls. It covers lumber, reinforced masonry, and reinforced concrete walls that meet all of these conditions:

• The wall holds back less than 4 feet of soil.
• There is no surcharge, including no load from a nearby structure or driveway.
• The ground behind the wall is level.
• The wall is not tiered or stacked.
• There are no problem soils.

For a wall like that, the county guideline can be used in place of custom construction plans. If a wall misses any one of those conditions, DPS requires construction plans prepared by a Maryland licensed design professional.

Here is a detail worth knowing. The guideline’s building sections cover lumber, reinforced masonry, and reinforced concrete walls. Many landscape walls today are dry-stacked concrete block. If that is the wall you want, ask DPS, or ask us, whether the simple-wall guideline fits your project or whether you need drawn plans.

The building code behind the county rules says the same thing in its own words. Under Section R404 of the International Residential Code, walls that hold back more than 4 feet of soil, or more than 36 inches with a surcharge, must be designed to accepted engineering practice. A few more county lines to know:

• A wall taller than 6 feet 6 inches counts as an accessory structure.
• A wall with a design height over 7 feet must also meet the county’s Special Inspection Program rules.
• Walls 4 feet or shorter are not subject to setback limits, unless the property borders a historic park.
• A wall cannot go in a drainage, utility, or similar easement unless the agency in charge of it approves.

Cross a county line and the rule changes

Burtonsville is close enough to two other counties that a short drive changes the rules.

In Prince George’s County, which begins just east of us around Laurel and Beltsville, permits go through the Department of Permitting, Inspections and Enforcement, called DPIE. DPIE requires a building permit for retaining walls taller than 2 feet. A wall 2 feet or shorter is exempt unless it supports a structure. That line is a full foot lower than Montgomery County’s. DPIE also asks that the retaining wall building permit be applied for before the site grading permit is issued.

In Howard County, which begins just north of us around Fulton and Scaggsville, permits go through the Department of Inspections, Licenses and Permits, called DILP. Howard County sets its own rules, separate from Montgomery County’s, so we confirm the current requirements with that office for every Howard County wall.

Your mailing address can fool you here. Some town names cover land in more than one county. Check the county on your tax bill or property record, not just the town in your address.

Before anyone digs: Miss Utility and the lines it will not mark

Every wall starts with a trench for its base. In Maryland, that means a call to Miss Utility first. You can call 811 or 1-800-257-7777, or you can file a ticket online. The Maryland window is no sooner than 3 business days and no later than 12 business days before the digging starts.

Here is the gap most people do not know about. The utility companies mark their own lines. They do not mark private ones. Miss Utility lists invisible fencing, sprinkler systems, well and septic systems and their power lines, and the water and sewer pipes that run from the meter to your house. Those private lines can run right along the edge of a lawn or planting bed, which is where many new walls go. If you have them, a private locating company can mark them before the digging starts.

How we handle a Montgomery County retaining wall permit

When a wall needs a permit, we handle the paperwork as part of the project. In Montgomery County, that includes:

• A site plan. DPS wants the wall drawn on your house location survey, with its distance to the lot lines and its height from grade to the top. The survey must be to scale and prepared by a Maryland licensed surveyor.
• Your HOA. Many neighborhoods have covenants about walls. The county does not enforce covenants, so check with your homeowners association before any block is ordered.
• Your neighbor, if the wall is on the line. The application needs their letter of approval.
• Well and septic. If your home uses a private well or a septic system, the wall has to keep the required distance from both.
• A licensed contractor on the permit. DPS lets a homeowner pull the permit in their own name. But it strongly suggests listing the contractor as the party responsible for the work, and a contractor must be properly licensed to get a building permit.

If you are planning a wall, our retaining wall installation team can look at your slope, what sits above it, and which county rules apply, before anything is dug.

This article is general information, not legal or engineering advice. Permit rules change, and the county has the final say. Before you build, confirm the current rules with Montgomery County DPS by calling 311 (240-777-0311 from outside the county), or with the permit office in your own county.

Frequently Asked Questions About Retaining Wall Permits in Montgomery County

Planning a wall in Burtonsville or nearby? Tell us where the wall will go and what it needs to hold back, and we will sort out the permit question before any digging starts. See our full hardscaping services in Burtonsville, MD, or contact our team to talk through your project.