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Unilock Home Additions & ADU: The Tampa Owner’s Guide
Unilock home additions and ADU projects in Tampa typically run $45,000 to $130,000 installed, depending on foundation work, square footage, and whether the structure ties into existing plumbing and electrical. We’re a Cedarwell company with a 365-Day Done Right Promise, and we write the price down before any work starts. Most Tampa homeowners reach out after they’ve realized their current layout no longer fits the family, or after a preliminary design conversation made clear that the paver or retaining wall product they assumed would carry the addition actually needs a proper structural base, drainage, and code-compliant connection to the house.
What surprises people most is how much of an addition’s long-term performance depends on what sits under the Unilock product, not the paver or wall unit itself. In Tampa’s sandy soil and wet-season saturation, a failed base or missing drain detail shows up within two or three years. The surface stones may look fine while the structure slowly moves. By the time cracks appear in the wall or the new room’s threshold stops sitting level, the repair usually means partial demolition, not a quick patch.
Which Unilock Models This Applies To
If you have a Unilock paver patio, walkway, retaining wall, or driveway apron that will need to be cut, relocated, or extended as part of a home addition or ADU build, this page applies to you. Common lines in Tampa yards include Unilock’s Brussels Block, Town Hall, Courtstone, Richcliff, and the U-Cara multi-face wall system. Each has a different joint width, paver thickness, and base requirement, and they do not interchange without visible pattern breaks.
The practical gotcha: Unilock pavers for vehicular use are rated thicker, often 60mm or 80mm, while pedestrian-only pavers run 50mm or less. If your addition adds a driveway extension or a new parking pad for the ADU, you cannot simply reuse the old 50mm stones from a walkway. A Tampa inspector will check the base depth and paver thickness against the intended load. We measure every existing Unilock unit and check the lot stamp on the back of a pulled paver before we quote replacement or extension work. Elmstead Remodeling Tampa is an independent contractor; we are not affiliated with Unilock, but we work with their products daily and keep dimensional references for the common Tampa-sold lines on hand.
For OEM Unilock units, matching is by size, finish, and manufacturing run. Unilock intentionally varies surface texture slightly by run, so an exact match from a different pallet can still read off under direct Florida sun. We order from the same regional distributors Tampa landscape suppliers use, and we hold aside a few extra units from every extension job for future repairs rather than leaving you to hunt down a discontinued color. If you’d rather not stay with Unilock, quality aftermarket pavers from Belgard or Techo-Bloc can work, but the color match to existing Unilock will be approximate, and we say that plainly before anything is ordered.
Styles & brands we work with
Signs Your Unilock Home Additions & ADU Is Failing
- Paver edges near the house have dropped or separated from the foundation. In Tampa’s summer storms, water gets under the sand base, washes out the bedding layer, and the pavers sink. When this happens at the point where a new addition meets the old patio, the threshold becomes a trip hazard and water starts running toward the slab, not away from it.
- Retaining wall sections bulge outward after heavy rain. Unilock U-Cara and similar wall blocks rely on geogrid reinforcement and clean drainage aggregate behind the face. When a previous job skipped the grid or used native sand instead of clean stone, hydrostatic pressure pushes the wall face. You’ll see horizontal cracks or a slight belly in the middle of the run before it fails outright.
- The new room’s French door or sliding door no longer closes square. This is often the first sign that the paver base under the door landing has shifted. Even a quarter-inch of movement changes the reveal on the door. It reads as a door problem, but the root cause is usually base settlement at the threshold.
- Water pools against the addition’s exterior wall after rain. Unilock patios need a slope of roughly 1/8 inch per foot away from the structure. When the slope flattens over time, or was never set correctly, water sits against the sill plate, wicks into the framing, and starts the slow work of rot and termite attraction. Tampa’s humid season turns this into a standing problem, not a drying problem.
- Efflorescence or white crust appears on new pavers within weeks of installation. This is water moving through the paver and carrying salts to the surface. It often means the base is not draining and water is trapped under the stones. On its own it’s cosmetic, but the trapped moisture is structural, and in Tampa it invites moss, ants, and eventual freeze-spall even in mild winters.
Replacement Cost & What’s Included
For a Tampa home addition or ADU that involves Unilock work, the full project range runs $45,000 to $130,000. That range covers permits, foundation, framing, roofing, electrical, plumbing, and finish work for an addition, with the Unilock site work, base correction, and drainage typically falling between $3,500 and $11,000 of the total depending on square footage and base depth. A standalone paver patio repair or extension, when not tied to an addition, usually lands at $3,500 to $11,000 as described in our paver patio pricing.
What drives the Unilock portion of the cost:
- Base depth and soil condition. Tampa’s sandy soil compacts poorly under load unless it’s properly excavated to a stable layer. A driveway apron or ADU parking pad needs 8 to 12 inches of compacted base; a walkway can often pass at 6 inches.
- Drainage correction. If water has been sitting against the foundation, we add a French drain, a channel drain, or regrade the slope before the pavers go back in. This is not an optional add-on; it’s the part that keeps the next contractor from writing you another repair quote in three years.
- Unilock unit replacement versus reuse. When pavers are cracked or spalled, we replace them from new stock. When they’re intact but sitting on a failed base, we reuse them after cleaning. Reuse saves material cost but the labor to pull, clean, and relay is similar to new install.
- Permit and inspection requirements. Any addition or ADU in Tampa requires permits. We pull them, schedule the inspections, and stand behind the work with the 365-Day Done Right Promise. The written line-item price includes the permit fees, and the price does not change after we start unless you change the scope in writing.
We also install named-brand finish materials in these additions: cabinets from KraftMaid, countertops from Cambria and Silestone, and fixtures from Kohler, Moen, and Grohe. The Unilock portion of the job gets the same written-price treatment as the framing and trim. Graham Stein writes the fixed scope before a single tool comes off the truck, and the crew leaves a photo of the clean-up before they go.
See the difference
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After
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After
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AfterDIY or Call Us?
You can safely check a few things on your own: look for standing water after rain, run a level across the pavers near the foundation, and note any door that suddenly sticks or rubs. Those observations help us quote the job faster. What you should not do is pull up Unilock pavers and attempt to re-base a section yourself near a foundation or retaining wall. The excavation depth, compaction, and drainage slope are code-specified, and doing it wrong means the next failure happens under the new addition’s sill plate, where the repair bill is much larger. Retaining wall work above three feet in Tampa also requires an engineered design, and wall removal without shoring is dangerous. If the wall is holding back soil or the pavers sit against the house, call us at (850) 779-4017 and let a trained technician look at it. The estimate is free, and the written price tells you exactly what the fix costs before you commit.
FAQs
A properly installed Unilock base with clean drainage aggregate and full compaction under a Tampa addition lasts 20 to 25 years or more before needing major work. A failed base shows problems within two to three years. The difference is almost always the base depth and drainage detail below the stones, not the paver itself. If your patio was installed without a geotextile separator or with native sand in the base, expect earlier settlement. Call (850) 779-4017, and we’ll tell you what your specific base looks like when we inspect it.
Yes, in many cases individual cracked or sunken pavers can be removed, the base corrected underneath, and the same stones reset. If the units themselves are intact, we reuse them and only pay for new sand, base material, and labor. If the pavers are cracked through or spalled from moisture, we replace just the damaged units with matched stock. The workmanship is covered by the 365-Day Done Right Promise, and the price is written before we start.
A paver repair or base correction next to a foundation usually takes two to four working days, including excavation, compaction, drainage, and resetting the stones. A full paver extension for a new ADU parking pad or patio tied into the addition may take five to seven working days depending on square footage and weather. The written price includes the schedule, and we keep noise confined to the hours we told your family to expect.
We keep a small on-truck stock of common Tampa-sold Unilock sizes and colors for repairs, and we order full pallets from regional distributors for larger extensions and fresh installs. When we order, we hold back extra units from the same manufacturing run so future repairs match. We also work with KraftMaid, Cambria, and Silestone for the finish materials inside your addition or ADU.
Contact Elmstead Remodeling Tampa for Your Unilock Addition or ADU
If your Unilock patio, wall, or driveway needs work as part of a home addition or ADU in Tampa, call (850) 779-4017. Graham Stein and the Elmstead Remodeling Tampa crew will schedule a walkthrough, measure your existing Unilock units, check the base and drainage, and hand you a written price before any work starts. We write it down before we start so nobody is guessing mid-project. A live person answers the phone, shoe covers and drop cloths go down on every visit, and the clean-up photo is sent before the crew leaves. You’ll know the number before the first tool comes off the truck.
Written by Graham Stein, Owner, Elmstead Remodeling Tampa at Elmstead Remodeling Tampa, serving Tampa and nearby areas.
