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Belgard Home Additions & ADU: The San Francisco Owner’s Guide
Belgard home additions and ADU construction in San Francisco typically runs $53,100 to $153,400 for a full addition, and $106,200 to $259,600 for a detached ADU with foundation, utilities, and hardscape tie-in. Most failures we see aren’t structural failure of Belgard materials themselves. What actually goes wrong is the integration: improper substrate prep under pavers, missing drainage behind retaining walls, or door thresholds that don’t meet Belgard paver elevations after the ground settles. The result is water pooling where it shouldn’t, pavers shifting at the transition point between the old structure and the new addition, and gaps that widen every fog season.
We stock Belgard-compatible transition pieces, edge restraints, and jointing sand on our trucks, and we can match existing Belgard paver lines so the addition doesn’t look bolted on. This page is the straight answer for San Francisco homeowners who already have Belgard product on the property and need the new work to match it, not fight it.
Which Belgard Models This Applies To
Belgard doesn’t make a product called “home additions” or “ADU.” What they make is the hardscape system that surrounds and supports those structures, and that’s where compatibility matters. The most common Belgard lines we work with on San Francisco addition and ADU projects are the Cambridge Cobble, Catalina, Lafitt, and Urbana paver series. Each has different dimensional tolerances, and that’s the gotcha: a Cambridge Cobble paver is 60mm thick, while a Lafitt slab runs 50mm. If you have a patio laid in Cambridge Cobble and the new ADU walkway is spec’d in Lafitt because “it looks close,” the surface heights won’t match at the seam. You’ll feel a lip every time you step from old to new.
Here’s how to identify what you have. Look at the side of an existing paver. Belgard stamps a lot number and series code on the bottom or side face of most units, but if that’s worn off, measure the thickness. 60mm is cobble-series. 50mm is slab-series. Take a photo of the paver face and texture pattern and our crew can match it from the Belgard catalog. For OEM versus aftermarket: Belgard’s own edge restraints and polymeric jointing sand are what we use on additions where the new pavers will see fog-driven moisture nine months out of the year. Aftermarket jointing products exist, and some are fine, but when the manufacturer spec mentions Gator Maxx or Techniseal as the approved sand pair with Belgard pavers, we use what the spec calls for. The guarantee we issue is only as good as the parts we can stand behind, and Belgard backs their own accessories with manufacturer documentation we can hand to you.
Styles & brands we work with
Signs Your Belgard Home Addition or ADU Integration Is Failing
- Pavers lifting or rocking at the transition line where the old patio meets the new addition. This usually means the base material under the new section wasn’t compacted to the same density as the original install, or a drainage layer is missing. The soil in San Francisco’s Outer Sunset and Richmond districts is sandy and shifts with winter saturation, which makes inconsistent compaction show up fast.
- Water pooling against the addition’s foundation or stem wall after rain. Belgard pavers are not waterproof. The slope underneath them is what moves water. If water is pooling at the wall line, the subgrade slope was likely pitched wrong or the edge restraint has sunken and trapped water against the structure.
- Gaps appearing between pavers where jointing sand has washed out. Fog condensation and light rain cycles are actually harder on jointing sand than heavy downpours. A fine gap that reappears month after month means the sand was swept in dry or the pavers are moving slightly, breaking the sand’s bond.
- Efflorescence, the white chalky film, spreading across pavers near the addition. This appears when water is moving through the paver bed and carrying mineral salts to the surface. It’s common after the first wet season, but if it keeps coming back year after year, water is being trapped under the pavers instead of draining through the base.
- Door thresholds or step risers no longer align with the paver surface. If the ADU door now sits too high or too low relative to the pavers outside it, the base has settled or heaved. This is both a trip hazard and a sign the subsurface wasn’t prepared for the structure’s actual load, not just foot traffic.
See the difference
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After
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AfterReplacement Cost & What’s Included
Here’s what San Francisco pricing looks like when we’re matching Belgard hardscape to a home addition or ADU. A full addition running $53,100 to $153,400 includes the structure itself, plus the hardscape tie-in: excavation, base compaction, paver matching, edge restraint, and jointing sand. The ADU range of $106,200 to $259,600 covers foundation, utilities rough-in, framing, finishes, and all exterior hardscape integration including walkways, patios, and any retaining elements where the grade changes.
What drives the spread is the condition of your existing Belgard install. If the original base is intact and flat, we’re matching color and relaying the transition area. If the base has failed, we’re pulling pavers, recompacting, and resetting, which adds labor hours but not usually new material cost. The written price includes parts, labor, debris hauling, and the paver-matched transition so the new work is indistinguishable from the old. And every job closes with the 365-Day Done Right Promise in writing: if anything fails in the first year, we return and make it right at no charge.
For a straight number on your specific ADU or addition, call (831) 610-5598. The estimate is free, and the price we give you is the price you pay. No change orders appearing a week into the job because someone “forgot” to include drainage.
DIY or Call Us?
An owner can check drainage slope with a four-foot level and a golf ball. An owner can photograph their existing Belgard paver face, measure its thickness with a tape measure, and confirm whether jointing sand is washing out after rain. That information helps us quote accurately. Where DIY goes wrong is compaction. A homeowner with a hand tamper cannot achieve the density under walkways and patio slabs that a plate compactor produces, and the first winter in San Francisco will prove it. Lifting and resetting pavers next to an ADU foundation also means working around gas lines, water service, and sometimes electrical conduit, which a homeowner should not be digging near without locate markings.
If the failure is at the foundation wall or where pavers meet the sill plate, get a professional to look before you lift anything. One call to (831) 610-5598 and we’ll tell you what we’re seeing and what it costs to fix. If it’s something you can handle with a bag of sand and an hour, we’ll tell you that too.
FAQs
A properly installed Belgard paver surface in San Francisco lasts 25 to 30 years before the base, not the paver, usually needs attention. The paver itself is concrete and will survive decades. What fails first in this climate is the base compaction and drainage layer under it, which is exactly why we document the base prep with photos before any paver goes down. Call (831) 610-5598 and we can walk through what your current base was likely built with and what’s recoverable versus what needs full recompaction.
Yes, most settling sections can be repaired by lifting the affected pavers, recompacting or adding base material, and resetting the same pavers. The deciding factor is whether the existing pavers are cracked or just out of level. If they’re intact, we reuse them and the repair cost stays in the low hundreds rather than thousands. Call (831) 610-5598 for a straight answer on what your specific failure needs.
A typical walkway and patio tie-in for an ADU runs five to seven working days once the structure is weathertight. That includes excavation, base prep, paver setting, edge restraint, and jointing sand. If we’re also handling retaining walls or a paver driveway, add another three to five days depending on square footage. We’ll give you a written schedule with the estimate, and we hit it or tell you why before it slips.
Yes, we stock common Belgard edge restraints, 60mm and 50mm transition pieces, and polymeric jointing sand on our trucks for the series we service most in San Francisco. For specific colors or discontinued lines, we order direct from Belgard distribution and have material on site within a few days. Bring us a photo of your existing paver face and we’ll match it before we quote the job.
Written by Curtis Lane, Owner, Bradford Remodeling Co – San Francisco, CA at Bradford Remodeling Co San Francisco, serving San Francisco and nearby areas.
