Additions Contractor in Santa Clara County

We serve six Bay Area counties — Alameda, Contra Costa, Marin, Napa, San Mateo, and Santa Clara — covering 47 cities from Oakland to San Jose. Our crews are based in Castro Valley, putting us within 45 minutes of every city we serve. We handle permits and know the building codes for each jurisdiction, which matters because requirements and fees vary significantly between cities.

We offer $0-down financing with approved credit, 12-month same-as-cash plans, and extended terms up to 15 years for larger projects. You only pay for completed, inspected work — we never ask for full payment before the job is done. Your project manager will walk you through every option during your estimate appointment. We also accept checks, ACH, and all major credit cards.

Yes. CSLB License #1078806 — verify it anytime at cslb.ca.gov. We carry $2M general liability, full workers’ comp, and are bonded per California law. We hold GAF Master Elite, Owens Corning Preferred, CertainTeed ShingleMaster, and James Hardie Elite Preferred certifications — each requires annual training and quality audits to maintain. We’re happy to provide proof of insurance before any work begins.

Most exterior projects in the Bay Area require a building permit. Fees vary by city — Oakland runs $200–$600, Peninsula cities often more. We handle the entire permit process: application, plan submission, and scheduling inspections. Permit fees appear as a separate line item in your estimate so you’ll see every cost upfront. For homes in WUI fire zones (Berkeley Hills, Oakland Hills, parts of Marin), we ensure full compliance with local fire-rated material requirements.

Home Additions costs in Santa Clara County vary by city — from San Jose to Milpitas. With median home values averaging $2,210,000 across the county, we see a range of project scopes. Hamilton Exteriors provides free, itemized estimates for every Santa Clara County project with no hidden fees.

Most single-story homes in Santa Clara County can support a second story addition with proper structural engineering. We evaluate your foundation, framing, and local zoning during our free consultation. Many homes in San Jose have successfully added second stories.

Most home additions in Santa Clara County take 3-6 months from permit to completion. Second story additions are typically 4-6 months. We handle all Santa Clara County permits and manage construction so you have one point of contact.

Yes. We handle all permitting for home additions in Santa Clara County and Santa Clara County — architectural plans, structural engineering, and city submissions. We work with Santa Clara County planning departments regularly.

In most cases, yes. We phase construction to minimize disruption. For second story additions, there may be a brief period where certain rooms are inaccessible. We create a detailed plan before starting so you know exactly what to expect.

Santa Clara County is one of California's most ADU-friendly regions. Santa Clara follows state ADU law (AB 68/SB 13) allowing detached ADUs up to 1,200 sq ft, junior ADUs up to 500 sq ft, and garage conversions on most single-family lots — often without additional parking requirements. Santa Clara has also adopted streamlined ADU permits with reduced fees. Hamilton Exteriors handles the full ADU process: design, engineering, permit applications, and construction. Most ADU permits in Santa Clara are approved within 60 days.

Yes. California's Title 24 energy standards apply to all roof and window replacements in Santa Clara and throughout Santa Clara County. For roofing, this means cool-roof-rated materials are required on low-slope roofs and recommended on steep-slope roofs to reduce heat gain. For windows, replacements must meet U-factor and SHGC ratings for Climate Zone 4 (which covers most of Santa Clara County). Hamilton Exteriors ensures every project meets or exceeds Title 24 requirements — we handle the energy calculations and compliance documentation.