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California / Builders / Hamilton Exteriors

Licence verified, no local permit history

Hamilton Exteriors

CSLB #1078806 · HAMILTON EXTERIORS · Corporation

Design-build ADU contractor based in Castro Valley. Builds detached ADUs, garage conversions and junior ADUs, built on site. Says it serves 10 California cities.

What the records show

Confirmed from public records
0ADU permits on file
5Years licensed
4Areas they work
ClearLicence standing

No ADU permits are on file under this licence in the cities we cover. Most California cities do not publish the contractor's name on a building permit, so this usually reflects what a city discloses rather than what a builder has built. Ask them directly for recent addresses and permit numbers you can look up.

Licence and insurance

California Contractors State License Board
Status
Licence clear
Classification
B, general building
Issued
2021-07-26 · expires 2027-07-31
Contractor bond
$25,000 AMERICAN CONTRACTORS INDEMNITY COMPANY
Workers' compensation
Covered GREAT AMERICAN INSURANCE COMPANY
Disciplinary action
None on record
Registered address
CASTRO VALLEY, Alameda County

Where they work

Confirmed from public records
CityStandingADU permitsPre-approved plans
Berkeley Licensed none no
Campbell Licensed none no
Concord Licensed none no
Danville Licensed none no

About the company

From their website

Hamilton Exteriors is an architect-led general contractor in Castro Valley covering roofing, siding, windows, ADUs, and home additions across Northern California. Design and permitting are handled in-house, and the firm arranges financing for larger jobs.

  • Founder Alexander Hamilton Li is a registered architect who also runs the construction side
  • Certified by GAF as Master Elite, Owens Corning as Preferred, CertainTeed as ShingleMaster, and James Hardie as Elite Preferred
  • Offers $0-down financing with terms up to 15 years and 12-month same-as-cash plans
  • Crew is based at 21634 Redwood Road in Castro Valley and travels to 47 Northern California cities

hamilton-exteriors.com

The company’s own description · licence shown on their advertising matches the state register

Founded
2018
Works as
Design-build ADU contractor
Builds
detached ADUs garage conversions junior ADUs
Handles permitting
Yes, on the owner’s behalf
Typical timeline
4-8 months for ADUs and additions
Warranty
Transferable 50-year warranty on roofing and siding, 20-30 years on windows
Financing offered
Yes
Contact
(650) 977-3351 · website
Owners named
Alexander Hamilton Li

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ADU Standards does not issue zoning determinations and does not endorse contractors. Licence details are from the California Contractors State License Board, checked 2026-08-15. A city that pre-approves a plan has vetted the plan, not the builder. Always confirm licence standing at cslb.ca.gov before you sign anything.