Home Additions & ADU in Marina - One Fixed Price, Permits Handled

Fast, Reliable Home Additions & ADU Across Marina

Home additions and ADU construction in Marina, CA runs $45,000 to $130,000 for a typical room addition, and $90,000 to $220,000 for a new detached ADU, with garage conversions landing between $30,000 and $80,000. The spread comes down to something most contractors won’t tell you up front: nearly every project on former Fort Ord land needs FORA environmental clearance before the first footer is dug, and the salt air off Monterey Bay punishes the wrong hardware inside eighteen months. We’re Barrett & Sons Construction, and we’ve been pricing and building additions here long enough to know both numbers matter. Call us at (877) 610-1318 if you want an estimate that includes the coastal-spec materials and the Fort Ord paperwork from day one.

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Why Barrett & Sons Construction Is Marina’s Preferred Home Additions & ADU Company

Tom Barrett started this company in 1998, and his sons run crews across Monterey County today. When we say we know Marina, we mean we’ve dug footers in the sandy dune soil off Reservation Road, spec’d stainless flashing on additions near the coastline, and sat through enough FORA reviews to know which forms drag and which sail through. Our Home Additions & ADU team doesn’t dispatch strangers. The crew that shows up in Marina is a Barrett crew, background-checked and uniformed, and Tom’s name, address, and license number are published for anyone to look up.

We answer our own phone. A live person picks up at (877) 610-1318, day or night. That matters when you’re four weeks into a garage conversion and the inspector flags a vapor barrier detail that should have been caught at rough-in. Every scope change, every allowance, every price adjustment comes as a written change order before work proceeds. No surprises at the end. Our 90-Day Done Right Promise is on every contract: if something isn’t right, one call brings Tom back.

Our Home Additions & ADU Services in Marina

Here’s what we handle most often for homeowners across the 93933 ZIP code, from the tract developments east of Highway 1 to the converted military housing near the old Fort Ord footprint.

ADU Design & Permitting

This is where Marina separates the experienced contractors from the ones who’ll stall your project. Nearly all additions on former Fort Ord land fall under FORA environmental protocols. If the parcel hasn’t been cleared for unexploded ordnance or contaminated soil, you’re not getting a building permit no matter how good your plans are. We handle the FORA paperwork, the Monterey County permits, and the engineering, so the design that gets approved is a design that can actually be built. A detached ADU with FORA clearance and a deep-pier foundation on Marina’s sandy subsoil typically runs $90,000 to $220,000.

Garage Conversion ADU

A garage conversion in Marina usually costs $30,000 to $80,000, and it’s often the fastest path to a rentable unit because the shell already exists. But there’s a catch: even if the garage was built after 1994, the city and county still need to confirm the parcel’s environmental status before you convert. We pull that sign-off, then address what Marina’s marine layer does to enclosed garages: vapor barrier upgrades, sill flashing, and ventilation that keeps the converted space from turning into a mold box by August. Expect the same written change orders and the same 90-Day Done Right Promise on this job as on a ground-up ADU.

New Detached ADU

Building a new detached ADU on Marina’s dune soil is not a job for a standard footing chart. The sand under most of this city compacts poorly and shifts. We see standard 12-inch footers settle unevenly and crack the subfloor before the punch list is closed. We specify engineered slab or deep-pier foundations from the start, and we size the vapor barrier for the near-constant marine layer, not just the winter rains. Coastal-spec hardware (hot-dip galvanized connectors, stainless flashing at every exterior transition) is not an upsell on a Marina ADU. It’s the difference between a building that lasts thirty years and one that rusts at the fasteners in three.

Junior ADU & Interior Conversion

If you have a bonus room, a large laundry, or part of a converted military home you want to turn into a junior ADU, the price is usually lower than a new build and the timeline shorter. But the inspection path still runs through Marina’s specific requirements. Older converted Fort Ord housing often has institutional-grade construction: thick concrete walls, steel framing in places, and utility runs that don’t match modern residential code. We retrofitted several of these over the years and the thing to know is simple: the cheap quote rarely factors the cost of bringing that old construction up to code before the JADU can be permitted.

Trusted Brands We Service in Marina

We don’t put mystery materials in Marina homes. On window replacements and additions that touch the exterior, we regularly specify Simonton, Ply Gem, and PGT frames because their coastal drainage channels and marine-grade finishes hold up to what comes off Monterey Bay. PGT’s impact-rated lines are a frequent choice for west-facing elevations near the shoreline. When we install these products, we’re not subbing out to a name you can’t check: every brand we carry is one you can look up, and every install is backed by our 90-Day Done Right Promise. If a window fails a rough-in inspection here, it’s usually because someone used an interior-drainage frame never meant for daily salt fog. We don’t.

Common Home Additions & ADU Problems We See in Marina Homes

• Rust-bled fasteners on coastal additions. An interior-grade electro-galvanized nail on a second-story addition off Abrams Drive starts showing rust streaks within a winter. Within eighteen months the heads can rust off entirely and lift flashing. We spec hot-dip galvanized or stainless on every exterior transition.
• Settling footers on sandy Fort Ord dune soil. Standard 12-inch footers are often not enough under Marina’s wind-deposited sand. We’ve seen new rooms rack their window frames before the punch list closed. Engineered slabs and deep piers cost more up front and settle less forever.
• Marine-layer moisture trapped against rough openings. Vinyl frames with interior-only drainage channels hold moisture against the sill plate here. By the time the walls are closed, the rough opening can be rotting. We use frames with exterior drainage channels and marine-grade finishes, and we flash every opening like it faces the bay.
• Converted military housing with institutional-grade bones. The old Fort Ord housing was built to military spec, not modern residential code. Thick concrete, steel framing, utility runs that don’t match anything in a current codebook. A room addition on one of these homes almost always needs retrofitting before the addition can be permitted.

Pricing for Home Additions & ADU in Marina, CA

We Also Serve Cities Near Marina

We run crews through Marina and the surrounding areas: Seaside, Castroville, Salinas, and Monterey. The Fort Ord permitting layer is specific to Marina, but the coastal-material reality follows the bay from Seaside down to Monterey. If you’re in any of those communities and want the same coastal-spec approach, call us.

FAQs - Home Additions & ADU in Marina