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Techo-Bloc Home Additions & ADU: The San Francisco Owner’s Guide
We install and build home additions and ADUs using Techo-Bloc hardscape materials across San Francisco, with typical project costs running $53,100 to $153,400 depending on square footage, foundation work, and site access. Most San Francisco homeowners reach out to us after realizing their existing foundation or retaining wall can’t support a second-story addition, or after a city planning review flags drainage issues tied to their current Techo-Bloc patio slope. The part that usually fails first isn’t the Techo-Bloc paver itself: it’s the base layer beneath it, which shifts on San Francisco’s clay-heavy hillsides and takes the surface with it.
Which Techo-Bloc Models This Applies To
For home additions and ADU work, the Techo-Bloc products we encounter most often are the Blu 60 mm and Industria 80 mm pavers, along with the Borealis and Villagio wall systems used in raised planter beds and retaining walls that often run right up against a new foundation line. Here’s the compatibility gotcha most owners don’t know: Techo-Bloc’s residential pavers are rated for pedestrian and light-vehicle use, so if you’re building an ADU with a driveway approach or a garage conversion, you need the 80 mm industrial thickness, not the 60 mm residential version. The 60 mm will crack under repeated vehicle weight within two to three years. Identifying your existing pavers is straightforward: flip one over and look for the Techo-Bloc name stamped on the underside, and measure the thickness with a tape. If you’re matching existing pavers for an addition that ties into an old patio, be aware that Techo-Bloc changes color blends between production runs, so even the same named color can shift slightly year to year. We always order from a single production batch when we’re extending a paver area.
We stock OEM Techo-Bloc pavers and wall blocks, and we’ll also install quality aftermarket equivalents when the original color has been discontinued. The aftermarket options from Belgard and Basalite in matching colorways sometimes cost 15 to 20 percent less, but the chamfered edge profiles are the difference to check: Techo-Bloc uses a distinctive beveled edge that aftermarket brands don’t always replicate, and the joint lines will look visibly different if mixed on the same surface. Elmstead Remodeling San Francisco is an independent contractor and not affiliated with Techo-Bloc, so we’re free to recommend whichever manufacturer’s product actually matches your site.
Styles & brands we work with
Signs Your Techo-Bloc Home Additions & ADU Is Failing
- Pavers rocking or shifting underfoot near the proposed addition footprint. This usually means the base layer has eroded or settled unevenly, which on San Francisco’s sloped lots often traces back to drainage washing fines out of the compacted base. A new foundation poured on top of that won’t sit level.
- Retaining wall blocks separating or leaning outward. Techo-Bloc wall systems rely on geogrid and proper backfill. When San Francisco’s winter rains saturate the soil behind a wall, hydrostatic pressure pushes blocks forward, and you’ll see a visible bulge at the midpoint of the wall face.
- Hairline cracks running across multiple pavers in a straight line. That line is usually the ghost of a joint in the concrete slab poured underneath the pavers as a base. The slab cracked, and the pavers followed. It’s the single most common failure point we see on San Francisco additions built in the 1990s and early 2000s.
- Standing water pooling against the foundation edge after rain. Techo-Bloc surfaces are permeable at the joints, but if the subsurface was never sloped to daylight or a drain, water sits against the new addition’s sill plate. That’s a slow leak into the crawl space, not just a puddle.
- Wall caps loose or missing entirely. Caps take the most abuse: sun, rain, people sitting on them, kids walking along them. When the adhesive bond fails, the cap rocks, and water gets into the wall core. On a hillside San Francisco lot, that water freezes extremely rarely, but it does erode the internal drainage gravel over several years.
See the difference
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AfterReplacement Cost & What’s Included
For a Techo-Bloc home addition or ADU project in San Francisco, the full installed range of $53,100 to $153,400 includes site prep, foundation work where needed, drainage correction, and the Techo-Bloc materials themselves. What drives the spread is three things: slope (flatter lots are cheaper to grade), access (rear-lot additions in the Richmond or Sunset districts where equipment can’t reach the back mean more hand-carrying labor), and whether the existing base layer can be salvaged or has to be excavated and rebuilt from scratch. On the smaller side, a garage conversion with a modest paver approach runs $35,400 to $94,400. A full attached ADU with foundation, utilities, and Techo-Bloc hardscape typically lands between $106,200 and $259,600 in San Francisco, where permit fees and structural engineering for seismic code add meaningfully to the total.
Every quote includes a written price before any work starts, with each line item named, so you can see exactly what the foundation costs versus the pavers versus the drainage. That’s the only way we work, and Graham Stein has been writing those line-by-line numbers since he first swung a hammer in California. All Techo-Bloc work carries our 365-Day Done Right Promise: if it’s not done right after we finish, we come back and make it right.
DIY or Call Us?
You can safely check a few things yourself: measure paver thickness, flip a paver to read the stamp on the underside, and note where water pools after rain. That information helps us quote accurately over the phone. What we don’t recommend is removing pavers near a foundation line yourself to inspect the base layer. On a sloped San Francisco lot, pulling pavers without shoring the edge can let the remaining surface slide, and a shifted paver field against an active foundation is a structural problem, not a cosmetic one. We’ve also seen homeowners chip the chamfered edges on Techo-Bloc pavers using pry bars without scrap wood protection, which turns a reusable paver into garbage. Call (831) 480-4497 before you start pulling anything up, and we’ll tell you honestly whether it’s worth a site visit or something you can photograph and send over.
FAQs
Techo-Bloc pavers installed on a properly compacted base with correct drainage typically last 25 to 35 years in San Francisco’s climate before needing surface-level attention, though the base layer may need recompaction at the 15-to-20-year mark if drainage was ever compromised. Call (831) 480-4497 and we’ll assess your specific slope and drainage pattern at no cost.
Yes, if the base layer failure is localized: we can cut out the affected area, recompact the base with new aggregate, and relay the original pavers when they’re intact and not chipped. If the failure runs under a foundation edge or across more than 30 percent of the paver field, replacement is usually the better long-term call. Either way, we’ll show you the numbers in writing before deciding.
Most additions and ADUs run 10 to 20 weeks from permit approval to final walkthrough, with the Techo-Bloc hardscape portion typically taking one to two weeks of that timeline depending on square footage. San Francisco’s permitting and inspection schedule adds time we can’t compress, but we sequence the work so your household keeps functioning throughout.
We stock the most common Techo-Bloc lines, including Blu 60 mm, Industria 80 mm, Borealis wall, and Villagio wall, and we order project-specific colors and quantities directly from Techo-Bloc distributors so the batch matches across your entire addition. You’ll never be asked to source your own materials or pick up a pallet from a yard.
If you’re planning a home addition or ADU in San Francisco and want a written price that names every line item before a single tool touches the floor, call Graham Stein and the Elmstead Remodeling San Francisco team at (831) 480-4497. Tell me what the room needs to do, and we’ll figure out the rest from there.
Written by Graham Stein, Owner, Elmstead Remodeling San Francisco at Elmstead Remodeling San Francisco, serving San Francisco and nearby areas.
