ADU Before & After in Rialto, CA
We’ve found that most Rialto homeowners don’t need more promises. They need to see what actually happens when a garage becomes a rental unit, or when a backyard slab turns into a detached studio. These projects are documented with permit sets, photo records, and final inspection sign-offs. The numbers are real. The work is real. Here’s what that looks like.
Recent Transformations
Garage Conversion ADU: 2-Car to 1-Bedroom Rental in South Rialto
The garage sat behind a single-family home near Alder Avenue, collecting storage boxes and seasonal items. The slab was 4 inches thick, within range for conversion, but the center seam had settled 3/4 inch. We brought in a structural engineer, specified a floating LVT floor system to bridge the variance, and ran new electrical from the main panel via underground conduit. The city required a 5-foot side setback verification, which we confirmed with a surveyor before the permit set went in. Result: a permitted rental unit that rents at market rate, with a documented photo record showing every phase from slab prep to final paint.
New Detached ADU: Backyard Studio in North Rialto Hills
This homeowner wanted a detached unit for aging parents, not a rental play. The lot sloped 18 inches from back to front, which meant we needed a stepped foundation rather than slab-on-grade. We specified the Abodu One system, 499 sq ft out of the box, and coordinated their factory delivery with our site prep timeline. The Rialto Fire Department required a 10-foot access path for emergency vehicle clearance, so we regraded the side yard and poured a 6-inch concrete walkway. Under Haven Standard Clause 1, the $187,000 written price covered design, permits, site prep, the modular unit, utility tie-ins, and final inspection. No change orders. The parents moved in 11 weeks after we broke ground.
Junior ADU & Interior Conversion: Attached Studio in Downtown Rialto
The room was technically part of the main house, accessed through a laundry area. For Junior ADU status, Rialto requires a separate exterior entrance, a kitchenette (not full kitchen), and either a new bathroom or documented shared bathroom access. We cut in a new door on the side elevation, ran a wet wall for the 3/4 bath, and specified a 12,000 BTU mini-split since the existing central system couldn’t handle the load independently. The homeowner’s original estimate from another contractor came in at $89,000 with no permit line item. Our free second opinion identified that they hadn’t budgeted for Title 24 energy compliance or the required HERS verification. Our written price of $67,500 included both. The permit cleared in 6 weeks.
ADU Site Prep & Utilities: Corner Lot in West Rialto
The pool had been non-operational for 14 years. The city of Rialto required a demolition permit, asbestos survey on the plaster, and a compaction report before we’d get the ADU foundation permit. We brought in a geotechnical firm for a soils report, which found expansive clay at 18 inches, not the 30-inch depth we’d hoped for. That changed our foundation spec from standard strip footing to a post-tensioned slab, a $4,200 line-item difference we flagged in writing before the homeowner signed. The pepper trees were in the city’s right-of-way, so we coordinated with Rialto Public Works for a replacement planting plan rather than removal. Total site prep and utilities: $34,800, documented with 147 photos across 9 visits. The detached ADU build starts next month.
Garage Conversion ADU: 1-Car to Efficiency Unit in East Rialto
The ceiling was 7 feet 2 inches, below the 7-foot 6-inch minimum for habitable space in San Bernardino County. We specified a scissor-truss retrofit to gain 10 inches of headroom without altering the roofline, which kept us clear of the planning department’s design review trigger. The 1960s Zinsco panel was a known fire hazard, so we upgraded to 200-amp service and relocated the new tankless water heater to the exterior side wall. The gas meter was at capacity, so we converted the whole property to electric water heating, which also satisfied the homeowner’s preference for solar compatibility. Written price: $78,500. The tenant moved in 14 weeks after permit submission.
New Detached ADU: Prefab Coordination with Dvele in South Rialto
This homeowner came to us with a Dvele reservation already in place, which is more common than you’d think. The gap most people hit: Dvele delivers a high-performance shell, but someone still needs to handle the Rialto foundation permit, the crane placement survey, the utility tie-ins, and the final inspection. We acted as the single-contract coordinator, which meant our written price covered our site prep plus Dvele’s delivery and set, with no finger-pointing if the slab didn’t match the module’s anchor points. The 3-foot grade change required a retaining wall and stepped terrace, which we designed into the landscape plan from day one. The battery backup qualified for SGIP incentives, which we documented in the permit set. Total project: $312,000, including the Dvele unit, our coordination, and all site work.
Want Results Like These?
Every project here started with a site walk and a written price. No estimate that evaporates when work starts. No designer and builder blaming each other. If you’ve got a written estimate already, we’ll give you a free second opinion. If you don’t, we’ll bring the clipboard. Call (951) 476-1467 to schedule your free estimate. A live person answers, 24/7.
Written by Nadia Ellery, Owner at Ellery ADU Studio Rialto, serving Rialto since 2015.