Retaining walls: when a hardscape job turns into an engineering claim

The honest answer is that a retaining wall is the one thing a landscaper builds that can hurt somebody three years after the check clears. Patios heave and get relaid. Sod dies and gets replaced. A four-foot segmental block wall on a Castle Rock slope, built in expansive clay without enough drain rock behind it, does something different. It leans for a season, then lets go with a neighbor’s patio on top of it. The claim comes to whoever’s name is on the invoice, from a policy year that already closed, and the first question the adjuster asks is whether an engineer ever looked at it. That’s the moment a hardscape job becomes an engineering claim. Here’s how it gets there, what the GL typically pays, what it doesn’t, and what covers the block on the driveway while the wall is still going up.

Why walls fail on the Front Range

Two things, and they work together.

Expansive clay. The soils along the Front Range piedmont swell when they get wet and shrink when they dry. Douglas County has a well-documented version of it.

A wall holds back soil. Soil that swells pushes harder than the soil the wall was designed for, if anyone designed it at all. Then it shrinks, the wall relaxes, and next spring it pushes again. Freeze-thaw adds a second cycle on top, every winter. A wall that would stand forever in decomposed granite above 9,000 feet has a different life in a Parker backyard.

Drainage. Water behind a wall is weight. Clean drain rock, a perforated pipe at the base, filter fabric, and somewhere for the water to go are what keep hydrostatic pressure from turning a landscape wall into a dam. Skip the drain rock to save a day, or backfill with the native clay because it was there, and the wall is carrying a load nobody calculated. Most of the wall failures we’ve looked at come down to drainage before they come down to anything else.

Then the surcharge. A driveway above the wall, a hot tub, a slope that keeps rising behind it. A wall that’s holding back more than dirt is a wall that needed a stamp.

The engineer question

Building departments set a height above which a retaining wall needs an engineered design and a permit, and most treat any wall that holds back a surcharge as needing one at any height. The threshold is different in Aurora than in Castle Rock than in unincorporated Douglas County, and it changes, so we don’t quote a number here. Ask the building department where the job is. Ask before you bid, not after.

Here’s why it matters to the claim and not just the permit. When a wall fails and someone’s hurt or something’s wrecked, the adjuster and the other side’s attorney both look for the design. If there’s a stamped drawing and you built to it, the argument is about workmanship and who deviated. If there’s no drawing and the wall was tall enough or loaded enough that the county would have required one, you built an unpermitted structure that needed engineering. Your GL carrier will typically still defend you. The conversation about whether it should pay just got longer, and your negligence is a lot easier for the other side to prove.

That is the difference between a hardscape claim and an engineering claim. Same wall. Different paperwork.

What the GL typically pays, and what it doesn’t

General liability has two halves, and a wall claim usually lands on the second one.

Ongoing operations covers what happens while you’re building: the Yanmar mini skid steer setting a 1,200-pound cap stone loses it on a wet morning and it rolls through the neighbor’s fence. Covered, under most standard forms, subject to the limit and the deductible.

Completed operations covers what your finished work does after you’ve left. The wall that lets go in year two. This is where the claim lands, and it’s the part of the GL that gets sublimited or dropped on cheaper forms. Look for it on the dec page as products-completed operations, with its own aggregate.

Then the exclusion that decides most of these.

The “your work” exclusion. Under most standard GL forms, the cost to repair or replace your own defective work is excluded. The wall you built wrong is yours to rebuild. That’s your warranty, and under most standard forms the GL isn’t going to fund it. What is commonly covered is the resulting damage: the neighbor’s patio the wall landed on, the car in the driveway below, the foundation that cracked when the slope moved, the person who was standing there.

Every wall claim turns into an argument about where that line sits. If the wall is the only thing that broke, the claim is mostly yours. If the wall took something else with it, the GL typically responds to that part. The adjuster reads the form and the facts, and the policy language controls.

The septic installer article has the same completed-operations problem in a different trade, including why the occurrence form keeps working after you cancel and why every old policy stays in the drawer. Read it if you build walls. The tail is the same.

The block on the driveway

Here’s the exposure nobody thinks about until it’s four pallets deep.

While the wall is going up, the materials belong to you. Block, caps, geogrid, drain rock, the pipe. On a big wall in Aurora that can be a meaningful pile sitting on a customer’s driveway for two weeks. A hailstorm cracks the caps. A trailer backs up to the rest on Saturday night. A delivery truck drops a pallet on the way in.

GL typically does not cover it. GL covers what you damage, not what you own. Contractor’s equipment typically does not cover it either. That policy covers the machine, at the number on the schedule, which the equipment schedule article covers. The materials fall in the gap between them.

An installation floater typically covers materials on site, in transit, and in temporary storage, from the time you own them until the owner accepts the work. It’s typically written per job or as a blanket for the year with a per-location limit. On a crew that regularly has more block on a driveway than it would want to eat, it’s a small line item for what it does. Once the owner signs off, the wall is theirs and the floater’s job is done. From then on it’s completed operations.

What the underwriter asks

Walls, and how tall. That’s the first question on a hardscape application, because the underwriter is pricing the tail. Expect to answer:

• Tallest wall you’ll build, and whether you build over the local engineering threshold at all.
• Whether you use an engineer on the tall ones, and whether you can produce the stamped drawings.
• Whether you pull permits.
• Whether you subcontract the excavation or the compaction, and to whom. The subcontractor article covers why the uninsured sub’s compaction is your wall.
• What’s behind your walls: drain rock and pipe, or whatever came out of the hole.
• Your loss runs.

An outfit that says “we don’t build over four feet, and anything with a surcharge goes to an engineer” is a different account from one that says “whatever the customer wants.” Both are insurable. They aren’t priced the same, and the second one should expect the completed-operations aggregate to be the number the carrier watches.

What we don’t control

The threshold. Every building department sets its own, and the only way to know the number for the job in front of you is to call the one with jurisdiction. We also don’t control how an adjuster draws the line between your work and resulting damage on a wall that took a patio with it, or whether a customer will pay for the engineer. What we can do is build the GL with completed operations at the full aggregate, put the floater on the job with the pile, and make sure you know where the “your work” exclusion sits before the wall does.

Where to go from here

The hardscape and paver installer page has the full coverage stack, the exposures, and the FAQs we hear most from wall builders. The Castle Rock and Douglas County page covers the soils and the local permit picture where a lot of these walls get built. If you’d rather work through it yourself first, the insurance readiness checklist has the questions in order. The landscaping insurance hub covers where hardscape fits with the rest of the green trades.

Serving businesses located in Colorado. Coverage is determined by the policy language and the carrier.