ADU Builder in Alameda County

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.

ADU costs in Alameda County vary by city — from Oakland to Alameda. With median home values averaging $1,228,000 across the county, we see a range of project scopes. Hamilton Exteriors provides free, itemized estimates for every Alameda County project with no hidden fees.

California's ADU laws make it possible to build on most residential lots in Alameda County. Alameda County has streamlined the permitting process. We evaluate your property's potential during our free consultation, including setbacks, utility access, and local zoning.

In Alameda County, you can build detached ADUs (up to 1,200 sq ft), garage conversions, attached additions, and junior ADUs (up to 500 sq ft). Many homeowners in Hayward are choosing detached ADUs for rental income or multi-generational living.

Many older homes in Alameda and Alameda County were built before modern seismic codes. While a roof replacement alone doesn't trigger a seismic retrofit requirement, it's the ideal time to reinforce roof-to-wall connections — especially for homes near the Hayward Fault. Hamilton Exteriors uses Simpson Strong-Tie hurricane clips on every roof we install, which improves earthquake resistance and meets California's latest building standards at no extra cost.

Yes. Parts of Alameda and the East Bay Hills fall within Cal Fire's Very High Fire Hazard Severity Zones (VHFHSZ). Homes in these zones must use Class A fire-rated roofing materials — which includes the asphalt, metal, and tile options Hamilton Exteriors installs. If your property is in a designated fire zone, we also ensure compliant ember-resistant vents and remove combustible material within 5 feet of the roofline as part of our standard installation process.