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Resources, guides, and updates from Type Five.
Can you build an ADU on a hillside in Oakland? Foundations, permits and cost
Yes. You can build an ADU on a hillside in Oakland or Berkeley, and steep sites usually end up on an engineered pier-and-grade-beam foundation designed from a soils report, often with a retaining wall or two. The harder questions tend to be local: fire-zone rules, fault and landslide maps, grading limits, and whether a crew can get equipment to the spot.
Building an ADU in San Francisco
Short answer: San Francisco allows ADUs in every zoning district that permits housing, through two paths: the State ADU program, which is ministerial and more flexible on Planning Code rules, and the Local program, which requires in-house Planning review. Type Five, a Berkeley design-build firm, designs your ADU, handles San Francisco permitting, and builds it on site.
JADU vs ADU: What's the Difference?
Short answer: a junior ADU (JADU) is a unit of up to 500 square feet carved out of the interior of a single-family home, including an attached garage. An ADU can be attached, detached, or a conversion, can be considerably larger, and can be rented without the owner living on site.
Site-Built vs Modular ADU: Cost, Quality and Timeline in the Bay Area
Choosing between a site-built vs modular ADU comes down to your lot more than the sticker price. Foundation, utility hookups, delivery, crane time and permits apply to factory-built units too, and Alameda County's ADU Guidebook says those costs can reach 20–40% of a prefab ADU's total, which is why the two often end up priced about the same. Factory-built can work well on a flat lot with clear truck access, while site-built wood framing gives you more room to fit the home to the tight, sloped lots common around the Bay Area.
Can I build an ADU on a multifamily property in Oakland?
Yes. California requires cities to allow ADUs on multifamily lots: conversions of non-livable space inside the building (at least one, and up to 25% of the existing units) plus up to eight detached ADUs on a lot with an existing multifamily building, not exceeding the number of existing units. In Oakland, those state rules sit on top of the city's multifamily ADU application categories and permit process.
Garage to ADU: Convert or Replace?
Short answer: California law allows ADUs in attached or detached garages, and cities cannot make you replace the parking you lose. Whether to convert the existing structure or replace it with a new backyard home depends on its foundation, framing, ceiling height, and location on the lot.
ADU Cost in the Bay Area: 2026 Price Ranges by Size and Site
ADU cost in the Bay Area typically runs about $400 to $550 per square foot all-in for a new detached unit. That works out to roughly $270,000 to $340,000 for a 500 sq ft studio and $390,000 to $490,000 for an 800 sq ft one-bedroom, based on ABAG's 2025 regional figures and Alameda County's ADU Resource Center. Slope, access, utility runs and city fees are what push your lot above or below that range.
SB 9 Lot Split Design-Build in the Bay Area
Short answer: SB 9 lets many owners of single-family lots in California split the lot once into two parcels and build up to two homes on each, through a ministerial (non-discretionary) approval. Type Five designs, permits, and builds new homes on lots created this way.
Is my lot big enough for a detached ADU in the Bay Area?
California law doesn't allow cities to set a minimum lot size for ADUs, and new detached ADUs need no more than 4-foot side and rear setbacks. In practice, whether a detached ADU fits on a Bay Area lot still depends on yard dimensions, trees, easements, fire access, and how far the new home sits from the main house.
Building an ADU in Sacramento
Short answer: the City of Sacramento offers free, permit-ready Shelf Ready plans for a studio and a one-bedroom ADU, plus a list of preapproved plans under state law AB 1332. If those layouts don't fit your lot or needs, Type Five designs a custom ADU, handles Sacramento permitting, and builds it on site.
Complete Guide to Berkeley ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Berkeley ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Hillsborough's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Hillsborough and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
San Rafael's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in San Rafael and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Top ADU Companies Oakland: Your Complete Guide to Choosing the Best Builder
Discover the best ADU companies in Oakland, offering quality design and construction solutions. Read on to find your perfect partner for your project.
The South Bay's Leading ADU Builder
Type Five is your trusted local homebuilding company
Palo Alto's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Palo Alto and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Complete Guide to Walnut Creek ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Walnut Creek ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Sebastopol's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Sebastopol and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Belvedere's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Belvedere and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Sonoma's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Sonoma and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Mountain View's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Mountain View and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Complete Guide to Peninsula ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Peninsula ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Prefab Homes in Bay Area: Complete Guide to Factory-Built Housing Options in 2026
Explore top prefab homes in Bay Area that fit your lifestyle. Discover options that blend style, sustainability, and affordability.
Oakland's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Oakland and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
The East Bay's Leading ADU Builder
Type Five is your trusted local homebuilding company
Prefab Homes in Berkeley: Complete Guide to Factory-Built Housing Options in 2026
Explore top prefab homes in Berkeley that fit your lifestyle. Discover options that blend style, sustainability, and affordability.
El Cerrito's Leading ADU Builder
Type Five is your trusted local homebuilding company
Lafayette's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Orinda and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Complete Guide to Marin ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Marin ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
The Bay Area's Leading ADU Builder
Type Five is your trusted local homebuilding company
Albany's Leading ADU Builder
Type Five is your trusted local homebuilding company
Top ADU Companies Marin: Your Complete Guide to Choosing the Best Builder
Discover the best ADU companies in Marin, offering quality design and construction solutions. Read on to find your perfect partner for your project.
Marin's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Marin and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Complete Guide to Oakland ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Oakland ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Top ADU Companies South Bay: Your Complete Guide to Choosing the Best Builder
Discover the best ADU companies in the South Bay, offering quality design and construction solutions. Read on to find your perfect partner for your project.
Top ADU Companies Bay Area: Your Complete Guide to Choosing the Best Builder
Discover the best ADU companies in the Bay Area, offering quality design and construction solutions. Read on to find your perfect partner for your project.
Top ADU Companies Berkeley: Your Complete Guide to Choosing the Best Builder
Discover the best ADU companies in Berkeley, offering quality design and construction solutions. Read on to find your perfect partner for your project.
Novato's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Novato and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Walnut Creek's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Walnut Creek and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Tiburon's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Tiburon and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Complete Guide to Sonoma ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Sonoma ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
House Prefabricated: 2026 Complete Guide to Modern Prefab Home Construction
Can prefab work on your California lot? Compare manufactured, panelized, and site-built options, with timeline, cost, and site access data for 2026.
Prefab Homes in Oakland: Complete Guide to Factory-Built Housing Options in 2026
Explore top prefab homes in Oakland that fit your lifestyle. Discover options that blend style, sustainability, and affordability.
Top ADU Companies Sonoma: Your Complete Guide to Choosing the Best Builder
Discover the best ADU companies in Sonoma, offering quality design and construction solutions. Read on to find your perfect partner for your project.
Mill Valley's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Mill Valley and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Berkeley's Leading ADU Builder
Type Five is your trusted local homebuilding company
Top ADU Companies Peninsula: Your Complete Guide to Choosing the Best Builder
Discover the best ADU companies in Peninsula, offering quality design and construction solutions. Read on to find your perfect partner for your project.
Complete Guide to Lamorinda ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Lamorinda ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Petaluma's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Petaluma and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Orinda's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Orinda and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Top ADU Companies Palo Alto: Your Complete Guide to Choosing the Best Builder
Discover the best ADU companies in Palo Alto, offering quality design and construction solutions. Read on to find your perfect partner for your project.
Redwood City's Leading ADU Builder
Type Five specializes in building accessory dwelling units (ADUs) in Redwood City and surrounding areas. As a full-service architecture firm and general contractor, we design and build ADUs with fixed pricing and exceptional quality.
Complete Guide to Palo Alto ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Palo Alto ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
House Prefabricated: 2026 Complete Guide to Bay Area Prefab Home Construction
Can prefab work on your Bay Area lot? Compare manufactured, panelized, and site-built options, with timeline, cost, and site access data for 2026.
Prefab Homes in California: Complete Guide to Factory-Built Housing Options in 2026
Explore top prefab homes in California that fit your lifestyle. Discover options that blend style, sustainability, and affordability.
Construction Schedule
What to expect for the building phase of your Type Five
Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Complete Guide to Sonoma ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Sonoma ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Choosing a Peninsula Accessory Dwelling Unit Contractor in 2026
Find the right Peninsula accessory dwelling unit contractor for your project. Get tips on selecting a skilled professional to ensure a successful build.
Complete Guide to Oakland ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Oakland ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Bay Area Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top Bay Area home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Complete Guide to Choosing a South Bay Accessory Dwelling Unit Contractor in 2026
Find the right South Bay accessory dwelling unit contractor for your project. Get tips on selecting a skilled professional to ensure a successful build.
Additional Dwelling Unit Cost: Complete 2026 Financing and Budget Guide
Explore the costs associated with additional dwelling units in this comprehensive guide. Learn to budget effectively and make informed decisions.
Complete Guide to South Bay ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top South Bay ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Best Home Builders in Oakland: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Best Home Builders in Sonoma: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Best Home Builders in Bay Area: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Sonoma Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top Sonoma home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
South Bay Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top South Bay home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Best Home Builders in California: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Peninsula Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top Peninsula home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Best Home Builders in Palo Alto: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Marin Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top Marin home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Palo Alto Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top Palo Alto home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Best Home Builders in Marin: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Best Home Builders in Berkeley: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Complete Guide to Peninsula ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Peninsula ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Berkeley ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Berkeley ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to South Bay ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top South Bay ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Choosing a Bay Area Accessory Dwelling Unit Contractor in 2026
Find the right Bay Area accessory dwelling unit contractor for your project. Get tips on selecting a skilled professional to ensure a successful build.
Oakland Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top Oakland home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Complete Guide to Marin ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Marin ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Choosing a Berkeley Accessory Dwelling Unit Contractor in 2026
Find the right accessory dwelling unit contractor for your project. Get tips on selecting a skilled professional to ensure a successful build.
Complete Guide to Choosing an Oakland Accessory Dwelling Unit Contractor in 2026
Find the right accessory dwelling unit contractor for your project. Get tips on selecting a skilled professional to ensure a successful build.
Complete Guide to Choosing an Accessory Dwelling Unit Contractor in 2026
Find the right accessory dwelling unit contractor for your project. Get tips on selecting a skilled professional to ensure a successful build.
Berkeley Custom Home Builder: A Complete Guide to Building Your Dream Home in 2026
Discover the top Berkeley home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Complete Guide to Bay Area ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Bay Area ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Choosing an Marin Accessory Dwelling Unit Contractor in 2026
Find the right accessory dwelling unit contractor for your Marin project. Get tips on selecting a skilled professional to ensure a successful build.
Complete Guide to Palo Alto ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Palo Alto ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Bay Area ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Bay Area ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Walnut Creek ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Walnut Creek ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Lamorinda ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top Lamorinda ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Choosing an Lamorinda Accessory Dwelling Unit Contractor in 2026
Find the right accessory dwelling unit contractor for your Lamorinda project. Get tips on selecting a skilled professional to ensure a successful build.
Complete Guide to Choosing a Walnut Creek Accessory Dwelling Unit Contractor in 2026
Find the right accessory dwelling unit contractor for your Walnut Creek project. Get tips on selecting a skilled professional to ensure a successful build.
Complete Guide to Choosing an Palo Alto Accessory Dwelling Unit Contractor in 2026
Find the right accessory dwelling unit contractor for your Palo Alto project. Get tips on selecting a skilled professional to ensure a successful build.
Best Home Builders in South Bay: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!
Complete Guide to ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to ADU Builders: How to Choose the Right Professional for Your Accessory Dwelling Unit
Discover top ADU builders who simplify home expansion with efficient designs and expert guidance. Read more to find the perfect fit for your needs.
Complete Guide to Choosing an Sonoma Accessory Dwelling Unit Contractor in 2026
Find the right accessory dwelling unit contractor for your Sonoma project. Get tips on selecting a skilled professional to ensure a successful build.
Best Home Builders in the Peninsula: Complete Guide for 2026
Discover the top home builders for your dream home. Learn what to consider and make an informed choice. Read the article to find your perfect match!