Unilock Home Additions & ADU Nationwide

Unilock Home Additions & ADU: The Palo Alto Owner’s Guide

We stock and install Unilock-compatible paver systems for home additions and ADU hardscaping in Palo Alto, with typical installed pricing from $45,000 to $130,000 for full addition projects and $90,000 to $220,000 for standalone ADU construction. Most homeowners discover their Unilock surface is failing when settling cracks appear between the Barron Park and Old Palo Alto neighborhoods, where clay-heavy soil shifts seasonally and leaves pavers uneven after the first winter rains. The fix is rarely the paver itself; it’s the base preparation, edge restraint, or jointing sand that has given way beneath it.

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Which Unilock Models This Applies To

Unilock segments its residential hardscape line into three tiers that we encounter on Palo Alto addition and ADU projects: the EnduraColor architectural series (Beacon Hill, Bristol Valley, Richcliff), the Classic series (Holland, Brussels Block, Courtstone), and the permeable Eco-Priora line required by some Palo Alto storm-water management plans. The paver model is stamped on the edge of every unit, but the critical spec is the laying pattern and edge restraint system specified in the original project file, not the paver face alone.

We source OEM Unilock where the color batch must match exactly, typically for additions that tie into existing patios less than five years old. For older surfaces where UV fading has shifted the tone, we spec quality aftermarket equivalents from Belgard or Techo-Bloc that we also stock, saving 15 to 25 percent on material without the mismatch risk. The gotcha: Unilock’s Series 3000 edge restraint is proprietary in width. Substituting generic L-profile edging on a curved walk will leave a 3/8-inch gap that collects joint sand and weeds within two seasons.

Signs Your Unilock Home Additions & ADU Is Failing

• Pavers rock underfoot or sound hollow when tapped. This indicates bedding sand migration, usually from inadequate edge restraint or a base layer that was compacted before reaching optimum moisture content. In Palo Alto’s dry summers, contractors sometimes compact base rock too dry; it settles later when winter moisture finally penetrates.
• Weeds growing thick through joints despite polymeric sand. The jointing material has degraded to loose particles, often because the original installer used standard sand where polymeric was specified, or because a pressure washer stripped the polymer binder in year three.
• Visible settling against the foundation or ADU slab edge. This is the most expensive symptom to ignore. It means the base was not stepped and compacted in lifts, or that organic soil was left in the excavation. We’ve rebuilt four such approaches near the Adobe Creek watershed where topsoil was simply graded over rather than removed.
• Chipping or spalling on the paver face, especially on driveway-adjacent addition walks. EnduraColor pavers carry a surface layer of finer aggregate; if that layer is thinner than 3/16 inch, de-icing salts or even hard-rubber tire scrubbing will expose the coarser body. Unilock’s warranty covers this, but only with original purchase documentation most homeowners have misplaced.
• Standing water more than 30 minutes after rain. Either the pitch is wrong (minimum 1 percent away from structures, which we verify with a laser level) or the permeable base has clogged with sediment. In Palo Alto’s Eichler-heavy neighborhoods with flat grades, this is often a design error rather than a material failure.

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Replacement Cost & What’s Included

Home addition hardscaping in Palo Alto runs $45,000 to $130,000 depending on square footage, structural tie-in requirements, and whether we’re matching existing Unilock that must be sourced as a special order. ADU construction ranges from $90,000 to $220,000, with the paver or concrete hardscape portion typically 8 to 12 percent of total project cost.

What drives the range: excavation depth (6 inches for pedestrian, 10 inches for vehicular), soil correction if we hit expansive clay, and whether the city requires a permit revision for the hardscape scope. We pull all permits and pass inspections as standard; the fee is line-itemed in your written quote, not absorbed and hidden elsewhere. Under Clause 1 of the Haven Standard, that quote is delivered before any work starts, every time. Our 365-Day Done Right Promise covers the installation; Unilock’s material warranty runs separately and we help file those claims when applicable.

DIY or Call Us?

An owner can safely check three things: confirm the paver model stamp on a loose edge unit, photograph the failure pattern for comparison, and verify whether the original project file lists a Unilock-authorized contractor (which affects warranty eligibility). What goes wrong fast: lifting settled pavers without releasing the edge restraint first snaps the plastic spikes and warps the profile; reusing disturbed bedding sand guarantees re-settling within months; and guessing at base depth without a probe or test pit risks building a repair on the same inadequate foundation.

We carry Unilock-compatible edge restraint, bedding sand, and jointing materials on our trucks, but we do not sell pavers alone; our license covers installed work, and we stand behind it. Measure twice, write it down, then we talk. Call (650) 446-9092 to schedule your free estimate.

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