Home Addition Contractor in Larkspur

We serve Northern California across three regions: the San Francisco Bay Area, Greater Sacramento, and the Central Valley. Our published guides cover 14 counties and 88 cities. Our Castro Valley and Sacramento offices support local estimating, permit coordination, and project planning across these regions.

Financing may be available for eligible projects with approved credit. Available terms depend on lender approval, project scope, and current programs. Your project manager can review the options that apply before work begins. We also accept checks, ACH, and major credit cards.

Yes. Hamilton Exteriors holds CSLB License #1078806, active general liability coverage, and the required contractor bond. We also hold GAF Master Elite and James Hardie Elite Preferred credentials. We can provide current proof of coverage before work begins.

Permit requirements depend on the project scope and local jurisdiction. Hamilton Exteriors coordinates required applications, plan documents, corrections, and inspections. Permit fees and allowances appear in the proposal before construction begins.

Most general contractors in Marin County are tradespeople first. They build what you describe, but they rarely design it. Hamilton Exteriors is different. Our founder, Alexander Hamilton Li, is both a licensed architect and a licensed general contractor (CSLB #1078806). That means the same person who designs your addition also oversees its construction. This matters for Larkspur homes because Marin County has some of the most specific building requirements in the Bay Area. From Wildland-Urban In

Larkspur home additions typically cost $200 to $500 per square foot (Hamilton Exteriors 2024-2026 project data). A 400-square-foot second-story addition runs $160,000 to $250,000 including structural engineering, permits, and construction. Room extensions on the ground floor are generally $120,000 to $200,000. Permit fees in Larkspur range from $5,000 to $15,000 depending on scope. Every Hamilton Exteriors estimate is fully itemized so you see exactly where your money goes.

Yes. The City of Larkspur Building Division requires building permits for all home additions. This includes structural, electrical, plumbing, and mechanical permits. Most additions also require Title 24 energy compliance documentation and, for projects over a certain size, fire sprinkler system compliance with NFPA 13D standards. Hamilton Exteriors handles the entire permit process.

Most Larkspur home additions complete in 12 to 20 weeks from permit approval. Second-story additions take 16 to 24 weeks due to structural complexity. Room extensions on an existing foundation complete faster at 10 to 14 weeks. Permit review by the City of Larkspur typically takes 4 to 8 weeks before construction can begin.

Most single-story Larkspur homes can support a second-story addition with proper structural engineering. Our structural engineers assess your existing foundation, framing, and soil conditions to determine if reinforcement is needed. Common upgrades include foundation bolting, cripple wall bracing, and moment frame installation to meet California seismic standards. Structural reinforcement typically adds $15,000 to $40,000 to the project (Hamilton Exteriors 2024-2026 project data).