Unilock Home Additions & ADU Nationwide

Unilock Home Additions & ADU: The Los Angeles Owner’s Guide

If you’re researching Unilock Home Additions & ADU in Los Angeles, the number to build around is $53,100 to $153,400 for a complete addition, installed, with the written scope and price locked before the first crew member shows up. That range assumes a site-built vertical addition or attached ADU using Unilock pavers and retaining wall systems as hardscape materials around the new footprint, which is where most Unilock-branded work actually happens on a residential job. Rowan Construction Group is an independent contractor, not affiliated with Unilock, and we stock and install Unilock-compatible materials for additions and accessory dwelling units across Los Angeles County.

Call (470) 298-9650

Homeowners usually discover this page because the pavers along a retaining wall have shifted, the soldier course at the edge of a patio is separating, or the base under a paver walkway has settled so badly it drains toward the new foundation instead of away from it. What they are actually seeing is the point where a Unilock paver product was installed without the edge restraint, drainage plane, or base depth the manufacturer specifies—and now the whole assembly is moving.

Key takeaways:

• Installed Unilock home addition and ADU work in Los Angeles runs $53,100–$153,400, depending on square footage, site access, retaining wall height, and whether we are repairing failed hardscape or starting clean.
• Unilock pavers fail predictably: edge restraint gives out first, base settlement follows, then surface pattern drifts. We see it in Los Angeles neighborhoods from Encino to Mid-City every week.
• Every Rowan quote is a written flat price with a written scope, under Clause 1 of The Haven Standard. No signed change order, no work proceeds.
• If the paver failure is tied to foundation drainage or a retaining wall over four feet, do not attempt repair yourself. That is a structural condition, not a weekend project.

Which Unilock Models This Applies To

Unilock manufactures three broad product families that show up on Los Angeles home addition and ADU projects: concrete pavers and slabs (the most installed hardscape product in the county), segmental retaining wall units, and permeable pavers for stormwater compliance. The specific Unilock lines we most often match on additions and ADUs are Brussels Block, Courtstone, Thornbury, and the Town Hall paver, along with the U-Cara multi-face retaining wall system when the addition sits into a slope.

Identification matters more than the model name stamped on the crate. Unilock products carry a manufacturing code on the side or bottom of the unit, along with the plant location and a batch date. We match on unit dimensions first: Brussels Block is manufactured in 6×9, 6×6, and 12×12 modular sizes with a 60mm or 80mm thickness. Courtstone is a tumbled unit with the same modular sizing but a wider joint. Mixing a 60mm Brussels Block with an 80mm Courtstone on the same walkway creates a lip that collects water and accelerates freeze-thaw spalling, even in Los Angeles’s mild climate. That is the kind of compatibility gotcha we check before writing a number.

For the addition itself, Unilock does not make framing lumber, shear panels, or roofing. What it makes is the ground-level system: pavers, retaining walls, steps, and the edge that ties the building pad to the landscape. The OEM versus aftermarket decision here is straightforward. Unilock manufactures the paver body; the base rock, bedding sand, geotextile, and polymeric joint sand are sourced from quarries and manufacturers that supply every hardscape contractor in Southern California. The aftermarket items are not inferior; they are the standard. But the Unilock unit itself should be purchased as genuine Unilock if you are matching an existing installation. A close-color aftermarket paver from a different plant will be visible in daylight, and the color difference gets worse as the units age.

Signs Your Unilock Home Additions & ADU Is Failing

• Edge restraint separation along the walkway or patio perimeter. The plastic or aluminum edging that holds the outside row of pavers has pulled away or cracked. Once the edge opens, the interlock in the field starts to spread. This is the first failure point on most Los Angeles installations because the edge restraint was either not spiked deeply enough or was the wrong profile for the paver thickness.
• Base settlement showing as a low spot that holds water after rain. The paver surface has dropped half an inch or more in one area, and water ponds after even a light Los Angeles winter storm. That means the compacted base below has lost density—usually from an unlined planter draining into the base, a broken irrigation line, or expansive soil movement in the San Fernando Valley.
• Polymeric joint sand washing out or growing weeds. The sand between the pavers is gone in patches, and weeds or ants are moving in. That tells you water is running across the surface and carrying the joint material with it. Left alone, the pavers begin to shift because there is nothing locking them laterally.
• A retaining wall leaning or bulging near the addition. Any retaining wall over 30 inches showing a visible lean is a structural problem, not a paver problem. In Los Angeles, walls over four feet require an engineered design and permit, and a bulging wall means the drainage behind it has failed and hydrostatic pressure is pushing the block forward.
• Step units rocking or a paver step pulling away from the threshold. A single rocking step is annoying. A full step unit separating from the door threshold means the sub-base under the step is eroding, and water is being directed toward the addition’s foundation by the settled hardscape.

Before

After

Replacement Cost & What’s Included

For Unilock home addition and ADU work in Los Angeles, the honest installed range is $53,100 to $153,400. That covers a site-built addition with Unilock hardscape around the footprint: foundation, framing, roofing, stucco or siding, plus paver walkway, patio, steps, and any low retaining wall. The spread is driven by square footage, site access (a rear addition in Silver Lake with no alley access costs more than a front-facing addition in Porter Ranch), soil condition, and whether the existing hardscape is salvageable or needs full removal and base rebuild.

A smaller scope—replacing failed Unilock pavers around an existing addition, rebuilding the base, and resetting the edge restraint—typically lands in the $8,260 to $21,240 range for a paver driveway and walkway scope, and $4,130 to $12,980 for a patio. You get the line-item breakdown before we start: paver unit cost, base rock, geotextile, edge restraint, polymeric sand, labor, and haul-away. The written quote is a flat price. If a change becomes necessary, a signed change order with its own line-item cost is produced before that change begins. There is no scenario where the final price drifts without paperwork in front of you first.

Every Rowan job includes a documented photo record of what we found under the pavers and what we installed, left with you when the crew finishes. The workmanship warranty is written into the contract, not referenced verbally. Under Clause 1 of The Haven Standard, the price is written before anyone starts.

DIY or Call Us?

What you can safely do yourself: identify whether the pavers are loose or just stained, confirm the edge restraint is the failure point by looking for a visible gap at the perimeter, and check whether water is ponding after rain. That is diagnostic work you can do without a tool belt. What you should not do is attempt a paver rebuild on a section of hardscape that ties into a retaining wall or sits against the addition’s foundation. Getting the base depth wrong on a Unilock paver system sends water into the foundation, and a retaining wall repair involves excavation and structural loading. If the wall is over 30 inches moving, call us. That is not a paver problem; it is a lateral load problem.

Grant Rowan will tell you the same thing on a walk-through: measure twice, say it once, show your work. If you want a written price to compare against what you are seeing, call (470) 298-9650 and we will come out, look at the Unilock installation, and tell you what is actually failing before we ever hand you a number.

FAQs

Call for Your Free Estimate

If your Unilock home addition or ADU hardscape is shifting, settling, or pulling away, call (470) 298-9650 and schedule a free estimate. We’ll walk the site, identify what failed, and hand you a written flat price with the scope in writing before any work starts. Grant Rowan’s crews serve Los Angeles and nearby areas, and every visit ends with a photo record of what we found. That is the standard.

Written by Grant Rowan, Owner, Rowan Construction Group at Rowan Construction Group, serving Los Angeles and nearby areas.