St. Helena homeowners need a contractor who understands the unique demands of Napa Valley living. From fire-resistant roofing in the WUI zones to seismic retrofitting on the West Napa Fault, every project requires local knowledge and an architect's eye. Hamilton Exteriors, led by Alex Hamilton Li, Architect and General Contractor (CSLB #1078806), brings that expertise to every St. Helena home.
We serve St. Helena with a full range of exterior and interior services, from roof replacements to custom home builds. Get your free quote to discuss your project.
Why St. Helena Homes Need a Specialist Contractor
St. Helena sits in the heart of Napa Valley, where the combination of wildfire risk, seismic activity, and wine-country aesthetics creates specific building challenges. Most of Napa County is designated as a Very High Fire Hazard Severity Zone (FHSZ) by CAL FIRE, requiring Class A fire-rated roofing materials and defensible-space compliance. The 2014 South Napa earthquake (magnitude 6.0) reminded everyone that the West Napa Fault is active, meaning structural connections and foundation work must meet current seismic codes.
A general contractor who has worked across Napa County knows these conditions and plans for them from the start.
Our Services in St. Helena
Roofing
St. Helena's hot, dry summers and WUI fire zone status make roofing material choice critical. We install GAF asphalt shingles, standing-seam metal, clay tile, and concrete tile — all with Class A fire ratings. A typical asphalt shingle replacement on a 2,000 sq ft home runs $18,000 to $28,000, including tear-off, synthetic underlayment, flashing, and permit fees. Metal roofs cost $28,000 to $50,000 and last 40 to 70 years. See our roofing services page for details.
Siding
Fiber cement siding from James Hardie is the most popular choice in St. Helena for its fire resistance and ability to handle the valley's temperature swings. We are a James Hardie Elite Preferred Contractor, the highest certification level. Siding replacement on a typical home runs $12,000 to $25,000 depending on square footage and trim complexity.
Windows
Energy-efficient window replacements improve comfort in St. Helena's hot summers and reduce cooling costs. Double-pane, low-E windows with vinyl or fiberglass frames cost $800 to $1,500 per window installed. We handle all Napa County permit requirements. Visit our window replacement services page.
ADUs
Accessory dwelling units are a smart way to add living space or rental income on your St. Helena property. A detached ADU (studio or one-bedroom) typically costs $150,000 to $300,000, including design, permits, and construction. Our ADU construction services cover everything from foundation to finish.
Home Additions
Adding square footage to your St. Helena home requires careful planning with the Napa County Building Department. A second-story addition runs $250 to $450 per square foot. A ground-floor addition runs $200 to $350 per square foot. Both include permits, foundation work, and finishing. See our home addition services page.
Custom Homes
We build custom homes from the ground up, managing every phase from site planning through final inspection. Custom home construction in St. Helena typically costs $350 to $600 per square foot, depending on finishes and site conditions. Visit our custom home building services page.
Decks
A well-built deck extends your living space into St. Helena's beautiful outdoor environment. Composite decking (Trex, TimberTech) costs $35 to $55 per square foot installed. Pressure-treated wood runs $20 to $35 per square foot. We handle all permitting and structural inspections. See our deck building services page.
Why Choose Hamilton Exteriors in St. Helena?
Architect-led. Unlike most St. Helena contractors, Hamilton Exteriors is led by a licensed architect and general contractor. Alex Hamilton Li evaluates your home as a complete system — structure, energy performance, fire safety, and design — before recommending solutions.
Napa Valley experience. We have completed projects across Napa County, including St. Helena, and know the local building codes, permit processes, and inspection quirks. The Napa County Building Department requires specific documentation for WUI compliance, and we handle it all.
Transparent pricing. Every estimate is fully itemized with per-square pricing for materials, labor, permits, and cleanup. You see exactly where your money goes.
Certified credentials. GAF Master Elite, Owens Corning Preferred, CertainTeed ShingleMaster, and James Hardie Elite Preferred. These certifications mean factory-backed warranties and manufacturer-grade installation standards.
Licensed and insured. CSLB #1078806, bonded, and fully insured.
St. Helena Permit Information
Every roofing, siding, window, ADU, addition, and deck project in St. Helena requires a building permit from the Napa County Building Department. Permit fees for a typical roof replacement run $400 to $800. ADU permits cost $2,000 to $5,000 depending on size. Your contractor should pull the permit; we handle all applications and inspections.
Get Your Free Quote for Your St. Helena Project
Ready to discuss your St. Helena home project? Call us at (650) 977-3351 or request a quote online. We provide free on-site inspections and fully itemized estimates. CSLB #1078806.
