Home Additions & ADU in San Diego - Plans, Permits & Build, One Fixed Price

Fast, Reliable Home Additions & ADU Across San Diego

A home addition in San Diego typically runs $53,100-$153,400 for a room or second-story build, while ADU construction ranges from $106,200-$259,600 depending on whether the unit is attached, detached, or converted from an existing garage. Most San Diego homeowners receive a written, line-item quote within 48 hours of our first site visit. Call (619) 536-0571 to schedule your free estimate.

Call (619) 536-0571

We’ve been building in San Diego since 2007. Our crews know the difference between a Clairemont lot that clears standard plan check and a Scripps Ranch parcel that needs Chapter 7A WUI fire-hardening assemblies because it sits east of I-15 in a Very High Fire Hazard Severity Zone. That local knowledge keeps permits from getting kicked back and timelines from ballooning. Dispatch and scheduling are coordinated from our San Diego office, and we carry the same documentation discipline to every job: written price before work starts, signed change orders for any adjustment, and a photo record of every visit.

Why Rowan Construction Group Chula Vista Is San Diego’s Preferred Home Additions & ADU Company

San Diego homeowners research contractors the way they research appliances. They read the three-star reviews. They want the price range on the page before they make contact. They prefer a text confirmation to a phone promise. We built our process around that.

Across 4,000-plus projects since 2007, every one has started with a written flat price and a written scope. No exceptions. Our 365-Day Done Right Promise is printed on every page and backed by a terms page, not an asterisk. If it’s not done right, we make it right. Under Clause 1 of The Haven Standard, the price is written before anyone starts. Under Clause 2, no change proceeds without a signed change order. That administrative discipline is why our projects finish within a few percent of the agreed cost.

Our crews are background-checked and uniformed. A live person answers calls 24/7. Every visit includes a documented photo record as standard, not an upgrade. We offer a Free Second Opinion on any written estimate: bring a competitor’s quote and we’ll review it line by line at no charge.

We know San Diego’s permitting landscape. We know which neighborhoods trigger HOA design review and which fall under Chapter 7A WUI requirements. That knowledge saves weeks on the calendar.

Our Home Additions & ADU Services in San Diego

ADU Design & Permitting

ADU design and permitting in San Diego starts with understanding which jurisdiction controls your parcel. The city of San Diego has its own ADU ordinance, but communities like Carmel Valley and Otay Ranch add HOA design review boards that can extend timelines well beyond what the city itself requires. We file the submittal packet ourselves, including the site plan, floor plan, elevations, and structural calculations. For parcels east of I-15 in Scripps Ranch or Rancho Bernardo, we spec Chapter 7A WUI-compliant assemblies from the first drawing: ignition-resistant cladding, multi-pane glazing, enclosed soffits, and ember-resistant venting. Getting that right in the initial submittal avoids the kickback that adds four to six weeks.

Garage Conversion ADU

Garage conversion ADUs in San Diego typically run $35,400-$94,400. The existing structure determines how much of that budget goes to structural upgrade versus finish. Post-WWII wood-frame garages in Clairemont, Linda Vista, and Mira Mesa often need seismic retrofitting to current standards: bolting the sill plate, adding shear walls, and sometimes upgrading the foundation. Coastal properties within a mile of the ocean need stainless or coastal-rated hardware to resist salt-laden humidity from the marine layer. We assess the existing framing, the slab condition, and the utility path before we write the price. The quote you receive is flat, with a written scope and a written warranty.

New Detached ADU

New detached ADUs in San Diego give the most design flexibility and the highest per-square-foot cost, typically landing in the $106,200-$259,600 range. Site prep matters: grading, utility trenching from the main residence, and in hillside areas like Mission Hills or South Park, engineered retaining walls. We coordinate the geotechnical report, the survey, and the utility connection in the same calendar as the building permit so nothing sits idle waiting for a separate sign-off. Our documented photo record tracks each phase, so you have evidence of what was found and what was done.

Junior ADU & Interior Conversion

Junior ADUs and interior conversions in San Diego work within the existing envelope, which limits structural cost but introduces code complexity: separate exterior access, a kitchenette with cooking facilities, and in most configurations a separate bathroom. In 1910s-1930s Craftsman bungalows in North Park, Mission Hills, and South Park, we often find outdated framing details, minimal insulation, and electrical panels that need upgrading to handle the additional load. We identify those conditions during the first site visit and build them into the written quote, not into a surprise change order later.

Second Story Additions

Second story additions in San Diego require reconciling the new structural load with the existing load-bearing path. In Scripps Ranch we framed a second-story addition on a post-2003 rebuilt home where both adjacent parcels were still original pre-fire stock, so our scope of work carried Chapter 7A ignition-resistant cladding and ember-resistant venting on the new walls while the existing first floor below stayed as-built. Because we pulled permits and managed the submittal ourselves, the city’s plan check on the WUI detailing ran in parallel with our rough-in, and we never had the project sitting half-finished waiting on a committee. That’s the discipline we bring to every second-story project in San Diego.

Room Additions & Sunrooms

Room additions and enclosed patios in San Diego range from single-family expansions to sunrooms that blur the line between indoor and outdoor space. The marine layer within a mile of the coast means we specify coastal-rated hardware and proper flashing details to prevent corrosion of connectors and joist hangers. Inland valleys like El Cajon and Santee hit 105°F+ in summer, so we schedule concrete pours and epoxy anchors within manufacturer temperature windows. The written quote includes the full scope: foundation, framing, roofing tie-in, electrical, HVAC extension, and finish.

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Trusted Brands We Service in San Diego

Our sourcing depth across fifty-plus vetted brands gives the written quote honest numbers rather than inflated ones. For roofing tie-ins on second-story additions, we specify GAF or Owens Corning shingles with matching ventilation components. For plumbing fixtures in ADU kitchenettes and bathrooms, we use Grohe valves and fittings with documented warranty support. We don’t list brands to impress. We name them because the spec sheet is part of what you sign, and because a named product with a named warranty is easier to service than a generic placeholder. Our San Diego warehouse stocks common hardware and fasteners for the brands we specify, which keeps the crew moving when a detail changes in the field.

Common Home Additions & ADU Problems We See in San Diego Homes

• Chapter 7A WUI kickbacks on east-of-I-15 parcels. A standard wall assembly submitted for a Scripps Ranch or Rancho Bernardo addition gets rejected because the parcel sits in a Very High Fire Hazard Severity Zone. We spec ignition-resistant cladding, enclosed soffits, and ember-resistant venting from the first drawing.
• HOA design review running on a separate calendar from city permits. In Carmel Valley and Otay Ranch, the HOA board can add weeks that the city never required. We pull the HOA requirements into the same timeline as the building permit so the work doesn’t stall waiting on a committee.
• Green-tagging rough-in before structural scope is reconciled. On second-story additions, an inspector signs off on electrical and plumbing before the new load path is verified against the existing structure, forcing a change order and re-inspection. We sequence inspections to match the structural milestones.
• Salt corrosion on coastal hardware. The marine layer within a mile of San Diego’s coast accelerates corrosion of standard metal connectors. We specify coastal-rated or stainless hardware on every coastal job, documented on the photo record.

Pricing for Home Additions & ADU in San Diego, CA

We Also Serve Cities Near San Diego

Our crews work throughout the metro area, including San Diego proper plus Coronado, National City, Chula Vista, and Lemon Grove. The same documentation discipline, the same written-price-first process, and the same 365-Day Done Right Promise apply in every city we serve. If you’re unsure whether your parcel falls under Chapter 7A WUI requirements or which HOA design review board has jurisdiction, we’ll verify that during our first site visit and build it into the quote.

FAQs - Home Additions & ADU in San Diego