ADU Before & After in Fontana, CA
Photos beat promises. Every project here started with a slab, a garage, or an underused corner of a Fontana lot, and ended with a permitted, inspected ADU with keys in the owner’s hand. Below is what that actually looks like, neighborhood by neighborhood, with the real constraints we hit and how we solved them.
Recent Transformations
Garage Conversion ADU - Southridge, Fontana
The owner had a tenant-ready garage but no permit path. We found the slab was 4 inches, within range for conversion per Fontana’s adopted 2022 California Building Code, though the 100-amp main required a 200-amp upgrade to handle the ADU load plus house demand. Under Haven Standard Clause 1, the all-in price, drawings through final inspection, was set at $78,000-$94,000 before we touched a wall. We pulled the electrical permit through Southern California Edison’s Fontana service center, ran a new 200-amp underground lateral, and documented every phase: slab moisture test, rough electrical, insulation inspection, and final. The photo record shows the original water heater relocation and the new mini-split mounting. Done in 14 weeks, keys handed over with a 365-Day Done Right Promise in writing.
New Detached ADU - Sierra Lakes, Fontana
Sierra Lakes lots run deep but narrow, and the setback variance here, the extra distance Fontana requires between the ADU and the property line, was the make-or-break detail. We measured 4 feet side and rear, which cleared with no variance needed, but the alley access meant San Bernardino County flood control had a say in the driveway cut. We coordinated that pre-application meeting in the first week, not after framing. The owner wanted a Tuff Shed shell with James Hardie siding to match the main house, so we specified the Tuff Shed TR-800 series with Hardie Panel in Monterey Taupe, then handled the foundation, MEP rough, and finish inside our single contract. Written price before start: $142,000-$168,000. Photo record includes the rebar tie inspection, the Tuff Shed crane set, and the final stucco color match under afternoon light. Permitted, inspected, occupied.
Junior ADU & Interior Conversion - North Fontana, near Summit Avenue
This was a classic North Fontana 1970s tract home with a side wing that had become a dumping ground for bikes and holiday bins. The owner needed rental income but couldn’t sacrifice the garage, and the lot coverage was already near max for a full detached unit. A Junior ADU, defined by California law as created within the existing walls of a single-family home, was the only path. We kept the shared wall, added a 30-inch efficiency kitchen with induction cooktop, and tucked a 36-inch shower into what had been a utility closet. The catch: the existing floor was 3/4 inch below main house level, so we floated a new subfloor to match without disturbing the slab. Haven Clause 1 price: $48,000-$62,000. Because it’s a JADU, no separate utility meter, no fire separation beyond 1/2-inch drywall, and no additional parking. Photo record shows the subfloor build-up, the wet wall rough, and the final certificate of occupancy from Fontana Building & Safety.
ADU Site Prep & Utilities - Hunter’s Ridge, Fontana
Not every before-and-after shows a finished ADU. This one shows what has to happen first, and what goes wrong when it doesn’t. The owner had a Cover prefab unit on order with a 16-week factory lead time, but the site was unbuildable: 8 percent slope, a rotting timber wall, and a sewer main that ran through the neighbor’s easement. We started with a soils report, then designed a 4-foot engineered block retaining wall with drainage behind it, brought in 22 cubic yards of fill to create a level pad, and negotiated a sewer easement amendment with the neighbor, documented in writing. The electrical service was 80 feet from the pad, so we trenched a new 1.25-inch conduit and set a pedestal. All of this was under our Site Prep & Utilities contract, with a written price of $34,000-$41,000 before the first shovel. The photo record, 147 images across 6 site visits, went to the owner and to Cover’s install coordinator so their crew hit the ground with no surprises. The ADU set three months later. That’s how prefab actually works when the site prep is treated as its own project.
Garage Conversion with Abodu Coordination - Downtown Fontana, near Citrus Avenue
Downtown Fontana’s older lots have charm and headaches in equal measure. This garage was technically a structure, but the slab was unsalvageable, settled with a 2-inch differential that meant any conversion would crack the finish floor in year one. We priced two paths under Haven Clause 1: slab replacement at $89,000-$105,000, or Abodu One unit on a new foundation at $112,000-$128,000. The owner chose the Abodu path for the 10-year structural warranty and the faster close-in. We handled the Abodu specification, the foundation engineering for their pier system, and the utility roughs, all in one contract. The narrow garage opening became a landscaped courtyard with a new 36-inch door punched into the Abodu end wall. Fontana’s historic district review, required for this block, added 3 weeks to permitting; we front-loaded that conversation with photos and a context statement. Final inspection passed, photo record delivered, 365-Day Done Right Promise in force.
Junior ADU from Unused Bedroom - Falcon Ridge, Fontana
The simplest JADU conversions are often the most technically precise. This bedroom had a window, a closet, and a shared hallway bath, but California JADU law requires either a separate entrance or an entrance through an attached garage. We added a 36-inch fiberglass door to the side yard, which triggered Fontana’s egress requirement: the existing window was 16 inches wide, 2 inches shy of the 20-inch minimum for emergency escape. We replaced it with a compliant slider, tied into the existing bedroom’s smoke detector circuit, and added a dedicated mini-split so the JADU’s HVAC load wouldn’t trip the main house breaker. The owner wanted to keep the hallway bath shared, which is allowed if the JADU is under 500 sq ft, so we added a privacy lockset and a signed use agreement for the rental file. Haven Clause 1 price: $38,000-$47,000. The photo record includes the door header install, the window rough opening reframing, and the final lockset test. Occupancy approved in 8 weeks.
Want Results Like These?
Every project above started with a site visit, a tape measure, and a written price before any work began. No call-for-quote runaround, no scope creep, no designer-builder finger-pointing. Call (909) 637-3715 to schedule your free estimate. We’ll bring the camera, the checklist, and the exact Haven Standard clause that governs your project.
Written by Nadia Ellery, Owner at Ellery ADU Studio Fontana, serving Fontana since 2015.