Where We Work

Ten cities. Ten different sets of ground rules.

Most contractors treat the Front Range as one job site. It isn't. The soil changes, the grade changes, and — the one that actually gets people in trouble — the retaining wall permit threshold changes from city to city.

A crew running “four feet everywhere” will build an unpermitted wall in Lakewood, in Littleton, in Boulder, and in Denver. We check every time.

Retaining wall permit thresholds, by city

Published by each jurisdiction, and different almost everywhere. Confirm with your building department for your specific address — thresholds change, and a surcharge (a patio, driveway, slab, or parked vehicle above the wall) removes the exemption at any height in most of these cities.

City	Wall permit trigger	Adopted frost depth
Denver	Denver runs three triggers, and the first one surprises people: any wall over 12 inches high needs a zoning permit. A building permit is required for walls over 4 feet. Masonry site walls and retaining walls over 6 feet get commercial engineering plan review. Structural calculations are required for walls retaining more than 24 inches of soil or over 4 feet measured from the bottom of the footing.	36 in
Lakewood	Lakewood is the trap in this metro. The exemption is 30 INCHES — not 4 feet — measured from grade to the top of the wall, and it disappears entirely if the wall supports a surcharge. A 3-foot garden wall that needs no permit in Golden needs one in Lakewood.	36 in
Arvada	Arvada uses the model-code threshold, stated plainly: a permit is required for retaining walls over 4 feet measured from the bottom of the footing to the top of the wall, or for any wall supporting a surcharge. Engineered, stamped structural plans are required.	36 in
Wheat Ridge	Wheat Ridge requires a permit for retaining walls over 4 feet high or supporting a surcharge. Clean model-code threshold plus the surcharge clause.	36 in
Golden	Golden states it from both directions, which makes it the clearest of the metro: a permit IS required for retaining and landscape walls over 4 feet tall, and engineering is required with it. Walls 4 feet or under, not supporting a surcharge, are exempt. Note that Golden's language covers landscape walls, not just structural retaining walls.	36 in
Littleton	Littleton is the strictest jurisdiction we work in. The city amends the model code DOWN: retaining walls are exempt only up to 2 FEET, measured from the bottom of the footing to the top of the wall — and there is no exemption at all if the wall supports a surcharge.	Not published — we confirm
Centennial	Centennial's Building Division points applicants to IRC R105 rather than publishing a local amendment. The unamended model-code exemption is 4 feet from the bottom of the footing to the top of the wall, with no exemption when a surcharge is present. Because we could not confirm the absence of a local amendment, we call the city before quoting a wall — we don't guess at a threshold.	Not published — we confirm
Parker	Parker requires a permit for retaining or block walls over 48 inches. The town's page doesn't state the measuring point, so we confirm it — a wall measured from the bottom of the footing crosses the line sooner than one measured from grade.	Not published — we confirm
Castle Rock	Castle Rock adopts the model-code exemption without amending it, so the threshold is 4 feet measured from the bottom of the footing to the top of the wall, with no exemption when a surcharge is present. The town also explicitly classifies retaining walls as Group U structures, and requires a stamped report from a Colorado-licensed engineer or architect at foundation inspection.	36 in
Boulder	Boulder's threshold is 3 FEET, not 4 — measured from the top of the wall to the bottom of the footer — and it comes with a second trigger most contractors miss: a retaining wall of ANY height on a slope of 15 percent or greater must be designed by a Colorado-licensed engineer. Boulder has a lot of 15 percent slope.	Not published — we confirm

Pick your city

Denver

City and County of Denver · 5,280 ft

Paver, flagstone, and concrete patios in Denver — built for Denver Formation claystone, a 36-inch frost line, and the city's 12-inch wall permit trigger.

Lakewood

Jefferson County · 5,656 ft

Patios, flagstone, and retaining walls in Lakewood. Lakewood permits walls over 30 inches — not 4 feet — and we build to a verified 36-inch frost depth.

Arvada

Jefferson County (with a small eastern portion in Adams County) · 5,525 ft

Paver patios, flagstone, and retaining walls in Arvada — expansive claystone, a verified 36-inch frost depth, and the 4-foot wall permit rule.

Wheat Ridge

Jefferson County · 5,348 ft

Patios and hardscape in Wheat Ridge — postwar lots, Clear Creek alluvium, expansive clay uplands, a 36-inch frost line, and permits for walls over 4 feet.

Golden

Jefferson County · 5,784 ft

Patios, walls, and steps in Golden — built for foothills grade, dipping Hogback bedrock, Clear Creek cobble, a 36-inch frost depth, and permits over 4 feet.

Littleton

Primarily Arapahoe County, with portions in Jefferson and Douglas · 5,397 ft

Patios, flagstone, and walls in Littleton. Littleton permits retaining walls over just 2 feet — the strictest threshold in the metro — and we build to it.

Centennial

Arapahoe County · 5,722 ft

Paver patios, flagstone, and walls in Centennial — built for Denver Basin expansive clay, with permit thresholds confirmed with the city before we ever dig.

Parker

Douglas County · 5,834 ft

Patios, walls, and flatwork in Parker — built for Douglas County soil that can heave when it gets wet AND collapse when it gets wet. Two hazards, not one.

Castle Rock

Douglas County · 6,224 ft

Patios, retaining walls, and steps in Castle Rock — a verified 36-inch frost line, Douglas County split soil risk, and stamped-engineering wall rules.

Boulder

Boulder County · 5,430 ft

Patios and retaining walls in Boulder, where walls over 3 feet need a permit, any wall on a 15% slope needs an engineer, and footings can hit floodplain.

One thing we won't tell you: how many freeze-thaw cycles we get

You'll see contractors on the Front Range quote a freeze-thaw cycle count — 55 a year, 105 a year, 150 a year. We went looking for a primary source behind those numbers and couldn't find one. So we don't use them.

What we can point at is the adopted code criteria: the Denver metro's weathering classification is Severe, the Air Freezing Index is 532, and the winter design temperature is 1°F. Those are real numbers from a real table, and they say everything a made-up cycle count was trying to say: the ground here freezes hard, and your base had better be dry.

Not sure if you're in?

Ask. If we can't get to you, we'll say so.

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