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Unilock Home Additions & ADU: The Orange County Owner’s Guide
A Unilock home addition or ADU project in Orange County typically runs $45,000 to $130,000 installed, depending on square footage, site prep, foundation work, and finish level. We carry Unilock pavers, retaining wall blocks, and wall caps on our material schedule and install them as part of larger addition and ADU builds. Most homeowners call us when they notice their existing Unilock hardscape has shifted or failed around a planned addition, or when they want the new ADU’s walkway and patio to match the main house.
You typically spot the problem at the transition points: where new foundation meets old paver runs, where a retaining wall has started to lean after heavy rain, or where the existing Unilock base course was never compacted properly and now shows dips and lippage. The fix is rarely just replacing one paver. The real issue is almost always the base layer under it, and that is what we price and correct in writing before any work starts.
Which Unilock Models This Applies To
This page covers Unilock products used in home additions and ADU construction across Orange County. The most common lines we specify are Brussels Block, Courtstone, Thornbury, Richcliff, and Unilock’s Estate Wall series for retaining and seat walls. Each line has different joint widths, thicknesses, and base requirements, and the compatibility gotcha most owners run into is mixing product lines. A Brussels Block paver is not a visual or dimensional match for Courtstone, even though both are Unilock. If your original patio was installed ten years ago with a discontinued color run, you need a match from current production dye lots, not just the same product name.
To identify what you have, check the underside of a loose paver for a raised Unilock stamp with the product name. Measure thickness: most Unilock driveway-rated pavers are 60mm or 80mm, while patio pavers run 50mm to 60mm. That thickness determines what base depth the addition’s walkway or patio requires. For ADU projects, we treat the outdoor hardscape as part of the permit package, not an afterthought, because tied retaining walls and drainage swales have to be shown on the plans.
Styles & brands we work with
Signs Your Unilock Home Additions & ADU Is Failing
- Paver lippage or sinking near the addition’s foundation line. The trench for the new foundation or utility lines was backfilled without mechanical compaction, and the base has settled. Water now pools against the house.
- Retaining wall leaning or bulging outward. The wall was built without geogrid reinforcement or proper drain rock behind it. Clay soil in Orange County holds water and expands, pushing the wall over time.
- Joint sand washing out after every rain. The pavers were dry-laid without edge restraint, or the bedding sand was too thick. Gaps open between pavers and weeds take over.
- Color fading or spalling on older pavers. Southern California UV exposure breaks down the surface sealant and efflorescence builds up. Spalling is surface concrete flaking that does not repair itself.
- Water pooling or draining toward the ADU slab. The original grade was not pitched away from the structure, or the paver base was laid flat instead of at a 1-2% slope. This is the most common cause of slab damage at the door threshold.
See the difference
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After
Before
After
Before
AfterReplacement Cost & What’s Included
In Orange County, the installed price for Unilock home addition and ADU hardscape work runs $45,000 to $130,000 for full-scope projects. That includes demolition of failed hardscape, subgrade excavation, base material, compacted aggregate, bedding sand, the Unilock pavers or wall block, edge restraint, joint sand, and finish grading. Smaller scoped repairs to an existing Unilock patio or walkway that tie into the addition can run $3,500 to $11,000 depending on square footage and base condition.
What drives cost: access (side yards in places like Fountain Valley or Garden Grove are tight), retaining wall height and need for reinforcement, drainage corrections, and whether the existing base is salvageable. We give you a written price before any work starts, line by line, so you know what you are paying for. Every completed project carries the 365-Day Done Right Promise: if the work does not hold within a year, we come back and correct it at no charge.
DIY or Call Us?
You can safely check for surface issues yourself: look for standing water after rain, run a level across pavers near the foundation, and inspect the edge restraint. What you should not do is lift pavers on an unstable base, rebuild a leaning retaining wall, or dig near a foundation without knowing where utility lines run. Retaining walls over three feet in California require an engineer’s detail and a permit, and a wall that fails can damage the addition itself.
If you see a leaning wall, sinkhole-sized settlement, or water collecting against your new ADU slab, call us at (562) 262-2907. We will walk the site, give you a straight number, and put it in writing.
FAQs
Unilock pavers are rated for 30 to 50 years of structural life, which means the paver itself holds; the base under it typically needs attention every 15 to 20 years depending on drainage and soil movement. In Orange County, clay-heavy soils and drought-to-deluge weather cycles shorten base life compared to regions with stable sandy soil. Call (562) 262-2907 and we can tell you within a few minutes whether your pavers are still sound or the base is the problem.
Yes, if the pavers themselves are intact and the issue is localized settlement, we can lift and re-lay the affected area with fresh base material and re-compact it. If the base has failed across the entire run or the wall has lost structural integrity, a repair will not hold and replacement is the honest call. We will tell you which one you need before any work is scheduled.
A standalone patio or walkway install in Orange County runs three to five working days including excavation, base compaction, paver laying, and joint sand. Tied retaining walls add two to four days depending on wall height and reinforcement requirements. We give you a written schedule with your written price, and we hold to it.
We order Unilock pavers and wall block directly for each project, which is standard practice across the industry and ensures you get the correct dye lot and product line. Our material schedule includes Unilock, KraftMaid, Cambria, and Silestone among the documented brands we install, with manufacturer specs and warranties that back our own guarantee.
Written by Curtis Lane, Owner, Bradford Remodeling Co – Orange County at Bradford Remodeling Co Orange County, serving Orange County and nearby areas.
