ADU Builder in Mountain View

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.

A detached ADU in Mountain View typically costs $220,000 to $420,000 for a 600 to 800 square foot unit with mid-range finishes. Garage conversions run $150,000 to $190,000. Junior ADUs start around $150,000. Permit and impact fees add $10,000 to $22,000. These figures include design, engineering, and construction. For a detailed breakdown, see our 2026 Bay Area ADU cost guide.

Plan on 8 to 12 months total from design start to move-in for a detached ADU. Garage conversions complete faster, typically 4 to 6 months. The permitting phase adds 2 to 4 months, though Mountain View's preapproved ADU program can shorten this. Construction itself runs 8 to 14 weeks for detached units and 10 to 14 weeks for garage conversions.

Yes. The City of Mountain View offers a preapproved ADU program with pre-designed plans that can reduce permit review time. These plans are cost-effective but may not fit every lot. We help you decide whether a preapproved plan or a custom design is the better choice for your property.

Yes. All ADUs in Mountain View require a building permit from the city's Building Division. California state law has streamlined the process, but you still need approved plans and inspections. Building without permits creates serious problems: code violations, insurance gaps, and complications when you sell. Permitted ADUs add verified value to your property.

If you own a single-family home in Mountain View, you almost certainly can. State law (AB 68, SB 13, AB 881) overrides most local zoning restrictions that previously blocked ADUs. Your lot must meet setback requirements (typically 4 feet from side and rear property lines), and the ADU cannot exceed certain size limits. A site feasibility review confirms what is possible on your specific property.