Unilock Home Additions & ADU Nationwide

Unilock Home Additions & ADU: The Sunnyvale Owner’s Guide

Unilock pavers and retaining wall systems used in Sunnyvale home additions and ADU projects typically run $45,000-$130,000 installed, depending on whether you’re extending a foundation with a paver patio, building an ADU with a Unilock walkway system, or integrating retaining walls into a hillside addition near the Cupertino border. We stock Unilock-compatible base materials, edge restraints, and jointing compounds for same-day repair and replacement on existing installations. Most Sunnyvale homeowners discover a Unilock hardscape failure when settling cracks appear after winter rains, or when polymeric sand washes out from between pavers on a sloped ADU approach - both signs that the base or bedding layer underneath has compromised.

Call (650) 405-3637

Which Unilock Models This Applies To

Unilock’s hardscape lines fall into distinct series, and the right repair approach depends on which system was originally installed. The Beacon Hill Flagstone and Richcliff lines - common on Sunnyvale ADU walkways for their permeable joint profile - use a 60mm paver thickness that requires a specific 1-inch bedding sand layer over compacted aggregate base. The Brussels Block and Umbriano series, often seen in Lakewood Village home additions near Washington Park, run 70mm and need a steeper edge restraint profile to prevent lateral spread under load. Check the paver edge for the stamped Unilock logo and series name; if weathering has worn it smooth, measure a full paver - 60mm versus 70mm tells us which bedding spec to match.

We source OEM Unilock replacement pavers and matching color lots where available, though discontinued colors sometimes require us to pull from Unilock’s West Coast distribution in Livermore or recommend a compatible aftermarket equivalent from Belgard or Techo-Bloc. The jointing compound matters as much as the paver itself: Unilock’s EasyPro polymeric sand activates with water and sets harder than generic silica sand, which is why we stock it on our trucks rather than substituting.

Signs Your Unilock Home Additions & ADU Is Failing

• Pavers rock or wobble underfoot. This means the bedding sand layer has eroded or the base aggregate has settled unevenly, often from poor initial compaction or water intrusion through failed edge restraints. In Sunnyvale’s clay-heavy soils near the Stevens Creek corridor, seasonal expansion accelerates this.
• Visible settling or low spots forming. The compacted aggregate base, typically 4-6 inches of Class II road base, has degraded or washed out beneath the bedding layer. On sloped ADU approaches, this usually starts at the down-slope edge where water concentrates.
• Polymeric sand cracking and washing out between joints. The jointing compound has broken down from UV exposure or was improperly activated during initial installation. Once gaps open, weed growth and ant colonization follow quickly in Sunnyvale’s mild climate.
• Edge restraints pulling away or heaving. Plastic or aluminum edging spikes have corroded or loosened, allowing the paver field to spread laterally. This is common where lawn maintenance equipment strikes the edge repeatedly.
• Efflorescence blooming across paver faces. White mineral deposits indicate moisture moving through the concrete substrate, usually from inadequate drainage below the base layer. It is cosmetic but signals a wet base that will degrade freeze-thaw performance if left unaddressed.

Before

After

Replacement Cost & What’s Included

These ranges reflect parts plus labor with no hidden line items. The spread depends on excavation depth needed, whether we can reuse existing pavers, and access constraints - tight side yards in Sunnyvale’s older neighborhoods like Birdland require hand-carrying material, which adds labor hours. Under Clause 1 of the Haven Standard, every quote is a flat written price with material costs, labor hours, and any subcontractor scope listed separately before work starts. Our 365-Day Done Right Promise covers the repair against settling or joint failure, and every visit includes a documented photo record of the excavated base condition and finished work.

DIY or Call Us?

An owner can safely inspect surface conditions: check for wobble with a straightedge, photograph efflorescence patterns, and verify whether edge restraints are still seated. Do not attempt base excavation or paver removal yourself. Unilock installations rely on precise base compaction - 95% standard Proctor density - and improper compaction guarantees failure within two seasons. The bedding sand layer must be screeded perfectly level; even 1/8-inch variance creates the wobble that destroys joints. More critically, many Sunnyvale ADU hardscapes sit over utility trenches or near gas lines installed during original construction. Call before you dig is not optional. If the failure involves a retaining wall over 30 inches tall, California building code requires engineered plans and permit inspection - a DIY fix here risks collapse liability and resale disclosure problems. For an honest assessment of whether your Unilock hardscape needs spot repair or full replacement, call (650) 405-3637 and we’ll schedule a free written estimate.

FAQs