Hamilton Exteriors is headquartered in Castro Valley at 21634 Redwood Rd. We are your neighbors, not a drive-in crew. Building a custom home is a multi-year commitment, and having your builder minutes away makes communication, site visits, and issue resolution dramatically easier.
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Custom Home Builder in Castro Valley
500+ projects
Since 2018
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Share your site and project goals. Our architect-led team will discuss feasibility, design, permits, and construction planning.
Custom home certifications, brands, and contractor credentials
Customer-Service Obsessed
Responsive from consultation through project closeout
Architect and general contractor
One accountable team
Licensed, bonded, and insured
Verified business credentials
Custom Home Services 
Start With the Custom Home Service You Need
Ground-Up Custom Homes
A complete design-build path from site study and program through architecture, engineering, permits, construction, inspections, and closeout.
Custom Home Design
Architect-led planning shaped by the lot, views, access, climate, structure, building systems, interiors, budget, and permit constraints.
Custom Home Permits
Coordination for planning review, architecture, engineering, energy documents, fire requirements, utility agencies, comments, and revisions.
Site-Specific Additions and Renovations
Architect-led work for existing homes when the new scope must respond to the original structure, site, systems, and architectural character.
Castro Valley is unincorporated Alameda County. Custom home permits go through the Alameda County Planning Department, which handles zoning review, building permits, and inspections. The permitting timeline for ground-up construction typically runs 4 to 8 months. Hamilton Exteriors manages all interactions with the county planning department.
Castro Valley offers diverse building sites. Valley floor lots in Proctor and near Castro Valley Boulevard are flat and straightforward to develop. Hillside lots in Five Canyons, Crow Canyon, and Palomares Hills offer views and privacy but require grading, retaining walls, and engineered foundations. Our architect designs homes that respond to each site's specific conditions.
Custom home construction costs in Castro Valley range from $350 to $550 per square foot depending on complexity, site conditions, and finish level. A 2,500 square foot custom home typically costs $875,000 to $1,375,000 to build. Hillside sites with significant grading can add $100,000 or more. Castro Valley's proximity to our HQ reduces mobilization and travel overhead.
Neighborhoods We Serve
Custom Home Building Across Castro Valley
Local planning starts with the site, neighborhood context, access, and applicable city review.
Crow Canyon
Crow Canyon's hillside lots offer privacy and views ideal for custom home sites. Larger parcels allow for expansive floor plans with outdoor living spaces. Grading and retaining wall engineering are key considerations we handle in the design phase.
Five Canyons
Five Canyons has limited infill opportunities but occasional tear-down rebuilds. Custom homes here must work within the community's design standards while achieving the owner's vision. Our architect navigates these requirements.
Palomares Hills
Palomares Hills offers some of Castro Valley's largest residential lots. Custom homes here range from modern farmhouse to contemporary designs, taking advantage of valley views and the semi-rural setting.
Proctor
Proctor's established grid of post-war homes occasionally presents tear-down opportunities on larger corner lots. Flat terrain simplifies foundation work and reduces site development costs compared to hillside builds.
Jensen Ranch
Jensen Ranch's family-friendly streets and proximity to schools make it attractive for custom home families. We design homes that maximize the available lot while creating private outdoor spaces.
Fairview
Fairview area parcels with gentle slopes offer custom home sites with character. The terrain allows for split-level designs that create visual interest and separate living zones within the home.
Cull Canyon
Properties near Cull Canyon Regional Recreation Area offer a secluded setting for custom homes. Larger lots, mature landscapes, and proximity to trails attract homeowners seeking a retreat within Castro Valley.
Redwood Road Corridor
Select parcels along the Redwood Road corridor present custom home opportunities with convenient access to shops and services. Our headquarters is on this corridor, giving us intimate knowledge of the area.
Project Management How Hamilton Exteriors
How Hamilton Exteriors
Manages Your Custom Home Project
Site and Program Study
We review the lot, survey, zoning, access, utilities, soil information, site constraints, and the homeowner's space requirements.
Design and Scope Coordination
Architecture, engineering, building systems, selections, permit needs, budget, and construction methods develop through one coordinated process.
Permits and Construction
We coordinate agency review, site work, foundation, structure, envelope, building systems, finishes, inspections, and documented scope changes.
Move-In and Closeout
We complete final inspections and the punch list, organize manuals and closeout records, and review applicable warranty terms.
Google rating 4.6 ★ from 47 public reviews
Homeowner Reviews of Our Construction Work
Public feedback from remodeling and related construction projects.
K
Kevin L
via Google
We hired them for a bigger renovation. Alex was very responsive, which I appreciated. We changed a couple requirements during the job and they worked with us on it without making it complicated. Overall, everything went pretty smooth and their quality of work is solid. I recommend them highly!
J
Jacob Rothwell
via Google
Alex Li helped me with my basement remodeling, they were super efficient, and the work came out better than I could’ve ever imagined! Thank me later!
M
Maan D
via Google
Had Hamilton Exteriors do a full kitchen renovation. Natasha helped a lot with scheduling and coordination which made things easier on our end. We got regular updates and didn’t feel left in the dark at any point. The team paid attention to details and made sure everything was installed properly. the whole process felt pretty smooth and the kitchen came out really clean. happy with the final result
L
Lekan Ajayi
via Google
This service was good and very efficient, all remodeling was done to liking. Jacob was a great worker and helped with answering questions that was needed. Would recommend to others.
Google rating: 4.6/5 from 47 public reviews
Read reviews on GoogleCompare Broad Custom Home Starting Points
Swipe to compare all options.
| Feature | Ground-Up Home | Hillside Home | Existing-Home Transformation |
|---|---|---|---|
| Starting condition | Vacant or cleared building site | Sloped or access-constrained site | Existing residence and systems |
| Early investigation | Survey, utilities, zoning, and soils | Survey, soils, slope, drainage, and access | Existing plans, field verification, and selective investigation |
| Main structural focus | New foundation and complete structure | Foundation, retaining, drainage, and seismic design | Connections between existing and new work |
| Design coordination | Whole-home program and systems | Home, site, views, and construction access | New scope, existing character, and occupied-home constraints |
| Dedicated guide | Ground-up custom homes | Start with custom home design | Site-specific renovation |
Custom Home Financing
Plan Your Construction Budget With Approved Credit
Financing may be available for eligible custom home construction scopes with approved credit. During early planning, we align the project scope and payment milestones, then explain which current lender programs and terms may fit the proposed work.
Ask which current options fit your custom home project.
Call Now (650) 977-3351 Frequently Asked Questions
Didn't find the answer to your question? Call Now (650) 977-3351
What areas do you serve?
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.
How does billing and financing work?
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.
Are you licensed and insured?
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.
Do I need a permit for my exterior project?
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.
How long does it take to build a custom home in Castro Valley?
Custom home construction in Castro Valley takes 12 to 18 months from permit approval. The design and permitting phase adds 4 to 8 months depending on architectural complexity and Alameda County plan review timelines. Total timeline from initial consultation to move-in is typically 18 to 24 months.
Do I need an architect for a custom home in Castro Valley?
California law requires a licensed architect or engineer to design residential structures over two stories or exceeding certain size thresholds. Even for single-story custom homes, detailed architectural plans with structural engineering are required for building permits in Alameda County. Hamilton Exteriors' founder is a licensed architect and general contractor, so design and construction are handled in-house under one contract.
Can I build a custom home on a hillside lot in Castro Valley?
Yes. Hillside lots in the Palomares Hills and Crow Canyon areas offer some of the best views in the East Bay. Hillside construction requires specialized engineering for foundations, retaining walls, drainage, and seismic bracing. We coordinate all geotechnical and civil engineering as part of our design-build process.
What permits do I need for a custom home in Castro Valley?
Custom home construction in Castro Valley requires building permits from the Alameda County Building Inspection Department. Permit fees for new construction typically range from $30,000 to $60,000, including plan check, school impact fees, and utility connection charges. We handle the entire permit process.
Your Next Step
Plan Your Project With a Clear Scope
Financing may be available with approved credit for eligible projects.
Tell us about your project. We usually call within 3–5 minutes to schedule the next step.
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21634 Redwood Rd Unit F, Castro Valley, CA 94546
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