A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Home Addition Contractor Across Coronado
Adding space to a Coronado home usually costs between $220 and $480 per square foot depending on the scope, with a full rear addition on one of the island’s older cottages typically landing in the $180,000 to $420,000 range. We’re a Home Addition Contractor team that works on Coronado’s specific housing stock every week, from Craftsman bungalows near the village core to mid-century ranchers closer to the Silver Strand. Our crews know this island’s alleys, its historic district rules, and what it takes to schedule a crane around a flag lot. If you’re weighing whether to add on or move, call (619) 376-2760 and Russ Delmar will walk you through what your specific home can support.
Key takeaways:
- Coronado additions run $220 – $480/sq ft; full rear additions on older cottages typically cost $180,000 – $420,000
- Opening walls in 1910 – 1940 Coronado homes almost always reveals wiring, framing, or waterproofing issues the quote must account for
- Flag lots with shared alleys require different crane and trenching logistics than open-lot builds
- Every price is written before work starts under The Kingswell Guarantee, with a 365-Day Done Right Promise in writing
Why Lodgewick ADU San Diego Is Coronado’s Preferred Home Addition Contractor Company
We’ve built our Coronado reputation one cottage at a time. The island’s homeowners talk to each other, and what they tell their neighbors is that we do what we say we’ll do: the written price doesn’t move unless a permit inspector requires something extra, and when that happens, we price it in writing and get approval before touching it. Coronado specifically rewards that kind of discipline because so much of this island’s housing stock hides surprises behind plaster and stucco.
Russ Delmar leads our team and has worked through dozens of Coronado additions, from room additions near Middletown to second-story builds in the village core. We answer our own phone, 24 hours a day. You won’t get a voicemail loop when you call about a change order or a scheduling question. The Kingswell Guarantee is the backbone of every project: a written price before work begins, a defined arrival window, a clean job site, and a written guarantee with a free return visit if anything fails within 365 days. A lodge is a small house on a larger property, and that’s exactly what we build for Coronado homeowners.
Room Addition Contractor in Coronado
A room addition in Coronado usually means extending the rear of a single-story cottage or converting an underused side yard into livable space, and those projects typically run $220 to $380 per square foot depending on what’s behind the walls. We quote the visible scope, then we write a specific allowance for what the inspection might turn up on a 1920s or 1930s house: knob-and-tube wiring, undersized studs behind a header, or building paper that’s long since stopped shedding water. Coronado’s coastal air has been working on these structures for 80 to 100 years, and pretending otherwise is how a contractor loses trust fast.
The opening-walls reality
Before we ever quote a Coronado room addition, we walk the crawlspace, check the panel, and look at the roof tie-in. On older homes, we write the quote so that a wiring upgrade or a shear-wall requirement is a line item, not a shock. That’s the Kingswell Way.
Working with historic materials
Many Coronado additions need to match Spanish Colonial Revival or Craftsman details, and James Hardie siding and trim lets us do that without the maintenance burden of the original wood. If your home is in a historic district like the Coronado Village core, we coordinate with the city’s design review process before the first permit drawing is finalized.
Second Story Addition Contractor in Coronado
A second story addition in Coronado is often the best answer for a family that’s outgrown a small single-story cottage but doesn’t want to give up the lot, and these builds typically run $280 to $480 per square foot because they involve structural reinforcement, roof removal, and often a full lateral retrofit once the walls are open. The island’s older homes were rarely framed to carry a second floor without new beams or shear plywood, and Coronado’s building department will require those upgrades once they see the plans.
Crane access and flag lots
In the historic village core, many Coronado cottages sit on narrow flag lots with rear yards reachable only through a shared alley. A second-story addition on those lots can’t rely on open street staging, so we schedule the crane and material drops around the alley’s access windows and coordinate with neighbors ahead of time. This is where local experience saves weeks.
What the permit triggers
Once you open the walls for a second story, the city will likely require a current panel, hard-wired smoke detectors, and lateral bracing on any wall that loses its original stucco shear resistance. We build those costs into the written estimate before we start, not as a surprise change order after demolition.
Trusted Brands We Service in Coronado
For Coronado additions, the materials matter more than they do inland. Salt air chews through standard galvanized fasteners and flashing within a few years, so we specify corrosion-resistant hardware and proven exterior systems. We work regularly with Abodu and Plant Prefab for prefabricated ADU and addition modules that arrive on a flatbed and get craned into place, plus James Hardie siding and trim for the exterior details that need to match a historic streetscape. Tuff Shed structures can serve as detached accessory buildings on larger Coronado lots where zoning allows. We keep these product lines on our radar for fast turnaround and know their installation requirements well enough to quote accurately the first time.
Common Home Addition Contractor Problems We See in Coronado Homes
- Knob-and-tube and spliced wiring. On a 1920s Craftsman near the Coronado Historical Association, we opened a wall to add a rear bedroom and found knob-and-tube spliced into Romex, two undersized 2×4 studs carrying the header, and paper-thin building paper behind the stucco that had failed years ago. Our inspector re-scoped the permit plan, we wrote a change order for a new 200-amp panel, a 4×12 LVL header, and a James Hardie rain-screen wall assembly, and the owner approved it in writing before we touched the framing.
- Failed waterproofing behind stucco. Coronado’s coastal humidity means any wall that’s been sealed with old building paper has likely been letting moisture into the framing for decades. A room addition that ties into that wall needs the waterproofing replaced as part of the scope, not as an afterthought.
- Flag-lot crane access. On alley-backed cottages in the village core, a rear addition or second story can’t be staged from the street like it can in National City or Chula Vista. Utility trenching has to go under the shared alley, and the crane schedule has to work around the neighbors’ access.
- Salt-air fastener failure. Standard galvanized hardware on exterior flashing and fasteners starts rust-staining through stucco within two years of a Coronado addition. We specify stainless or coated fasteners on every salt-exposed connection and detail the flashing so water moves away from the framing.
Pricing for Home Addition Contractor in Coronado, CA
Here’s what you’re actually looking at for a Coronado addition in 2025 dollars:
- Room additions: $220 – $380 per square foot, full scope from foundation to finish
- Second story additions: $280 – $480 per square foot, including structural and lateral upgrades
- Sunroom additions: $180 – $300 per square foot for a conditioned three-season room
- Bathroom additions: $45,000 – $110,000 depending on finish level and whether plumbing lines run under a slab or alley
- Garage additions or conversions: $120,000 – $260,000 for a detached ADU with separate utilities
- Bump-out additions: $60,000 – $140,000 for a 100 – 250 square foot extension
What moves the number most is what’s behind the existing walls. A 1910 corner-lot wall with no shear plywood will trigger a full lateral retrofit once the permit is reviewed, and that’s several thousand dollars of framing and hardware. Coastal waterproofing allowances run higher in Coronado than inland because the salt air punishes shortcuts. We write every allowance into the contract, and if the inspection reveals something the allowance doesn’t cover, we price and approve it in writing before doing the work. Call (619) 376-2760 for a free estimate on your specific home.
We Also Serve Cities Near Coronado
Beyond Coronado, our crews take on home additions in San Diego, National City, Chula Vista, and Imperial Beach. If you’re just over the bridge or down the Silver Strand, the same written-price guarantee and 365-Day Done Right Promise applies. Call us and we’ll tell you straight whether your project fits our schedule.
Serving Coronado, CA - Our Local Coverage Area
We’re based in the Coronado 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 Home Addition Contractor in Coronado
We stop, document what we found, and write a change order with a specific price for the repair, which you approve in writing before we continue. On a 1920s Craftsman near the Coronado Historical Association, we found knob-and-tube spliced into Romex and paper-thin building paper behind stucco, and the owner approved a new panel, LVL header, and rain-screen assembly in writing before we touched the framing. The allowance structure in our original contract already anticipated the likelihood of these discoveries on a home of that age. Call (619) 376-2760 and we’ll walk through what your specific home likely contains based on its era and location.
Yes, but the schedule has to be built around the shared alley from day one. On Coronado’s alley-backed flag lots, utility trenching runs under the alley, and crane access for lifting trusses or prefab modules has to be coordinated when neighbors can still get in and out. We’ve done these builds enough to know the city’s right-of-way requirements and the practical reality of scheduling material drops, and we write the crane and trenching costs into the original quote so there’s no surprise. The second story itself doesn’t eliminate alley access; it just requires the staging to be planned differently than a street-facing lot in National City or Chula Vista.
In most Coronado historic district cases, no. You’ll preserve the street-facing facade, and the addition goes to the rear or side where the design review board can see it’s compatible without removing original features. Coronado’s historic preservation overlay means we draw the addition to match roof pitch, window proportions, and materials, not to replace them. You’ll likely lose the stucco only on the wall we’re actually tying into, and we replace that waterproofing as part of the scope. The original windows usually stay unless you want them upgraded for efficiency.
We write the waterproofing allowance based on what we can see in the crawlspace and exterior, then we add a specific contingency line for what the coastal air has likely done to the hidden layers. Coronado’s salt humidity has been working on these cottages for 80 years, so we don’t pretend the building paper is still doing its job. The allowance covers replacing failed paper or adding a rain-screen assembly where the stucco has to come off. If the inspection reveals something beyond that allowance, it’s priced and approved in writing before we touch it. No surprises at the door.
Opening the walls typically triggers a current electrical panel with arc-fault breakers, hard-wired smoke and carbon monoxide detectors, lateral bracing on any wall losing its shear resistance, and possibly a foundation anchor retrofit if the bolts aren’t up to current code. On beach cottages, the city may also require upgraded waterproofing details where the addition ties into the existing envelope. We build every one of these into the written estimate before demolition begins, because a permit review on Coronado’s 1910 – 1940 housing stock almost always flags at least one of them. Call (619) 376-2760 to get a free estimate that accounts for your home’s actual age and condition.
Call us at (619) 376-2760 to schedule your free estimate. Russ Delmar and the Lodgewick ADU San Diego team serve Coronado with written pricing, real arrival windows, and a guarantee that’s in writing before the first nail goes in.
Written by Russ Delmar, Owner at Lodgewick ADU San Diego, serving Coronado since 2010.
