A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Vallejo, CA
Adding an ADU in Vallejo means working with homes built before modern building codes existed, on lots that were subdivided a century ago. Most of our Vallejo jobs start the same way: a 1920s Craftsman or Victorian with a detached garage, knob-and-tube wiring still feeding half the house, and a backyard with just enough room for a 600 to 800 square foot unit. We plan around all of it – the seismic retrofits, the cast-iron drain lines, the shallow setbacks – and put the full price in writing before any work begins. Call (424) 328-5746 to talk through what’s possible on your lot.
Why Vallejo Homes Are Different
Vallejo’s housing stock is genuinely old. Drive through the Heritage District or up toward the hills off Tennessee Street and you’ll see Victorians and Craftsman bungalows built between 1890 and 1940, many still on their original foundations. That matters for ADU work in two ways. First, a backyard cottage or garage conversion often triggers foundation and seismic upgrades before framing can start – the main house usually isn’t bolted to its foundation, and the city will require it when you pull permits for attached or detached square footage. Second, the original electrical and plumbing are frequently knob-and-tube and cast iron, which means a chunk of the ADU budget goes toward rewiring and replumbing the main house just to bring the service up to code.
Vallejo’s Mediterranean climate helps on the construction side. Cool, foggy summers and wet winters mean we build year-round, though foundation and trenching work can stretch from November through March when the ground is saturated. We specify insulation and moisture barriers that handle both the marine layer and the winter rain – a Vallejo ADU has different envelope requirements than one in the East Bay hills or up in Napa. The city also enforces hillside and historic-district rules in certain pockets, so setback and height restrictions vary block to block. A lot in the flats off Sonoma Boulevard is not the same as a hillside lot above the ferry terminal, and we price them accordingly.
Our Main Vallejo Services
Most Vallejo homeowners come to us for one of two things: a detached backyard ADU, or square footage added directly to the existing house. Each has its own page with local pricing and details.
ADU Builders in Vallejo
Backyard cottages and garage conversions are the most common ADU projects we handle in Vallejo. The city’s deep lots – many 5,000 to 7,500 square feet – usually have room for a detached unit, but the old detached garages often need structural reinforcement before they can be converted, and underground cast-iron drains frequently need replacement. We build with brands like Abodu and Cover for prefab ADUs, and we also do fully site-built cottages when the lot or historic district rules require a custom approach. ADU Builders in Vallejo covers pricing, timelines, and what the city will ask for.
Home Addition Contractor in Vallejo
When the main house needs more room – a family suite, a larger kitchen, a primary bedroom – we plan the addition around Vallejo’s older framing and electrical systems. Many of these homes were built before earthquake bracing was standard, so the structural work is often as significant as the new square footage itself. We coordinate the foundation retrofit, the panel upgrade, and the addition as one permit package, which keeps the city review cleaner than doing it in pieces. Home Addition Contractor in Vallejo walks through scope and cost for attached additions.
Room Addition Contractor in Vallejo
A single room addition in Vallejo – an office, a guest room, a sunroom – usually means bumping out from an existing wall and tying into a roof that may be original to the house. We see a lot of these on Craftsman bungalows where the floor plan is tight and the lot has side yard to spare. The city’s setback rules on shallow lots can limit how far out you can go, so we confirm the allowed envelope before we draw anything. Room Addition Contractor in Vallejo has the full breakdown.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Brands We Service in Vallejo
We build with and source from brands Vallejo homeowners can research on their own: Abodu and Cover for prefab ADUs, Tuff Shed for accessory structures, and James Hardie for cladding that stands up to the marine layer without rotting. Parts are ordered to the project site, not a warehouse across the Bay. See our brands for the full list and what each one is best suited for.
Pricing for ADU Company in Vallejo, CA
| Service | Typical range in Vallejo |
|---|---|
| Detached backyard ADU (400 sq ft) | $120,000 – $180,000 |
| Detached backyard ADU (600 sq ft) | $180,000 – $260,000 |
| Detached backyard ADU (800 sq ft) | $240,000 – $340,000 |
| Garage conversion ADU | $90,000 – $150,000 |
| Prefab ADU (400-600 sq ft) | $140,000 – $220,000 |
| Home addition (300-500 sq ft) | $120,000 – $220,000 |
| Home addition (500-900 sq ft) | $200,000 – $380,000 |
| Room addition (single room) | $70,000 – $130,000 |
| Foundation upgrade / seismic retrofit | $15,000 – $40,000 |
| Electrical panel replacement | $4,000 – $8,000 |
| Cast-iron drain line replacement | $6,000 – $15,000 |
| Full knob-and-tube rewire | $10,000 – $25,000 |
Vallejo pricing runs higher than newer suburban tracts because of the seismic and infrastructure work folded into nearly every project. An ADU on a lot with healthy wiring and a bolted foundation will come in at the lower end; an old Victorian with original systems will land at the higher end. Whatever the number, you get it in writing before work starts – no change orders billed later.
Neighborhoods We Serve in Vallejo
We work across Vallejo, from the historic streets near downtown to the hillside lots above the waterfront. The neighborhoods below are where we’re most active, but the same crew and pricing model apply anywhere in city limits.
- Heritage District
- North Vallejo
- East Vallejo
- Glen Cove
- Bay Terrace
We schedule Vallejo work throughout the week, and our crews stage from the San Francisco Bay Area office so materials and permits move without a long lead time. Once a project starts, you’ll know the live arrival window and see photo updates as the work progresses.
Service Area – Cities Near Vallejo
Beyond Vallejo, we serve several nearby cities where the housing stock and permitting realities are similar. If you’re in Rodeo, CA, Hercules, CA, Pinole, CA, or Albany, CA, the same written-price guarantee and 365-Day Done Right Promise apply. Each city has its own page with local details.
Serving Vallejo, CA - Our Local Coverage Area
We’re based in the Vallejo area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About ADU Company in Vallejo
Once the design and permit package is submitted, the city’s review timeline drives the start date – we don’t control that part. What we control is everything before it: the site visit, the written quote, and the plan set can usually be in hand within a few weeks of the first call. Call (424) 328-5746 to get the process moving.
Yes, often. Hillside lots and properties in historic districts can trigger additional review for height, setbacks, and exterior materials. We handle the full permit package, including any supplementary applications, so you’re not chasing paperwork. The estimate includes the permit scope we expect, and we confirm it before you sign.
It can, and we tell you early. Many Vallejo homes still have knob-and-tube wiring or cast-iron drain lines, which the city will require you to address when adding square footage. We include these line items in the written price up front, not as a surprise during demo. Call (424) 328-5746 for a free estimate that accounts for your house’s actual condition.
Call (424) 328-5746 to schedule your free Vallejo estimate. A live person answers, and you’ll get a written price before any work starts.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Vallejo Customers Say
"Solid job. Cabinets arrived late but they adjusted the schedule."
- Eli K."Plumbing and electrical passed on the first inspection."
- Alan B."Communication was the best part. I always knew what was happening that week without having to ask."
- Dolly N.
