ADU Commons Bay Area

Plan, finance, permit and build a backyard home in the SF Bay Area. Book site visits and design, compare prefab units, get pre-qualified for construction loans and hire foundation crews, all from vetted local pros.

Category: Home & Garden

Sellers: LongbeamADUBuilders, FoldstoneModular, BaylightHomeFinance, StampwellPermits, LotlineDesignStudio, BenchcutSiteWorks

• Studio Modular ADU, 420 sq ft — A factory-built studio with a full kitchen, a walk-in shower, vaulted ceiling and a wall of glass doors to the garden. Built indoors in our Richmond factory in 10 to 12 weeks, state-approved as factory-built housing, then delivered and set by crane in one day. Price covers the finished unit delivered within 75 miles of Richmond; foundation, utility hookups and permits are separate. Choose your finish package at checkout. Price: $164,000.00 Category: Prefab & Modular Homes
• ADU Construction Loan Pre-Qualification — Find out how much you can borrow to build your ADU before you commit to a design. Share your address, rough budget and timeline, and a Baylight loan officer calls you within one business day with loan options sized on your home's value after the ADU is built, an estimated monthly payment, and the documents you will need. Pre-qualification does not affect your credit score. Category: Construction Lending
• ADU Permit Expediting — We take your ADU application from drawings to issued permit. A pre-submittal review against your city's rules, a complete application package, filing and fee payment, tracking of every review deadline, and a weekly status email. Includes one round of plan-check correction responses; add a second round if you expect a complex review. Serving San Francisco, the East Bay, the Peninsula and San Jose. Price: $3,200.00 Category: ADU Design & Permitting
• ADU Design & Permit Drawings — A complete architectural design for your ADU, from first sketch to a permit-ready drawing set: site plan, floor plan, elevations, sections, coordination with the structural engineer and the Title 24 energy report. Includes two rounds of schematic revisions and our support through plan check. Price depends on the size of the unit; garage conversions and junior ADUs fall in the smallest size. Price: $9,800.00 Category: ADU Design & Permitting
• ADU Foundation Package — Layout, excavation, forming, rebar and concrete for an ADU foundation up to 500 sq ft, built to your engineer's plans and ready for a site-built or factory-built unit. Includes soil haul-off and the foundation inspection. Choose a slab-on-grade or a raised perimeter foundation for sloped lots and crawl-space access. Larger footprints are quoted after a site visit. Price: $19,500.00 Category: Site Work & Foundations
• Free ADU Build Estimate — Thinking about a backyard cottage, a garage conversion or an in-law unit? Tell us about your lot and what you want to build, and a Longbeam project manager calls you within one business day. After a short call we send a written, fixed-price build estimate with a realistic timeline for your city. No cost and no obligation. Category: ADU Building & Remodeling
• One-Bedroom Modular ADU, 640 sq ft — A factory-built one-bedroom home with a separate bedroom, a full bathroom, an open kitchen and living room, and space for a stacked washer and dryer. Built in our Richmond factory in 10 to 12 weeks, state-approved as factory-built housing, then set on your foundation by crane in one day. Price covers the finished unit delivered within 75 miles of Richmond; foundation, utility hookups and permits are separate. Price: $232,000.00 Category: Prefab & Modular Homes
• Home Equity & Cash-Out Refi Consultation — Already have equity in your home? A 30-minute call with a Baylight loan officer compares a home equity line of credit, a cash-out refinance and a renovation loan for your ADU or garage conversion, side by side: rate, monthly payment, closing costs and how each handles construction draws. You leave with a written comparison. Free, with no obligation. Category: Construction Lending
• Bay Area ADU Permit Checklist — The two-page checklist our expediters use before every ADU submittal: what to confirm before you design, the drawings and documents a Bay Area city expects, what to have ready at submittal, how to get through plan check, and the inspections after the permit is issued, plus the four most common reasons ADU permits stall. PDF, instant download after checkout. Price: $19.00 Category: ADU Design & Permitting
• ADU 101 for Homeowners — A practical two-and-a-half-hour workshop for Bay Area homeowners thinking about an ADU. We cover what state law now allows, detached vs. attached vs. garage conversion, real 2026 costs per square foot, financing options, the permit timeline and how to pick a team. Bring your address and questions; you leave with a plan for your next three steps. Third Saturday of every month, 10:00 am to 12:30 pm, at our Berkeley studio. 30 seats. Price: $35.00 Category: Education and Training
• Utility Trenching & Hookups — We trench and lay the underground lines your ADU needs, up to 60 feet from the main house: water, sewer, electrical conduit and gas if required, with backfill, compaction and the underground inspection. Add a new sewer lateral to the street if your city or your camera inspection calls for one, or an electrical panel upgrade to carry the new unit. Price: $8,900.00 Category: Site Work & Foundations
• ADU Feasibility Site Visit — A 90-minute visit from a Longbeam project manager to answer the first big question: what can you build on your lot? We measure setbacks and access, check the sewer lateral, electrical panel and slope, flag trees and easements, and walk you through detached, attached and garage conversion options with a realistic cost range for each. Add a written zoning and utility memo to share with your designer and lender. Price: $495.00 Category: ADU Building & Remodeling
• Factory-Installed Solar Kit — Rooftop solar sized for a Foldstone ADU and installed in the factory, so it arrives ready to connect. A 3.2 kW array with microinverters meets California's solar requirement for new detached ADUs in most cases. Your electrician makes the final utility connection on site. Add a home battery for backup power during outages. Price: $11,800.00 Category: Prefab & Modular Homes
• San Francisco ADU Guide (Official) — Building in San Francisco? Start with the City's official accessory dwelling unit pages: which ADU program fits your building, how to apply for the permit, the design and permitting resource sheet, and the required notices. We walk every San Francisco client through it before their first submittal. Category: Information and Resources
• Bay Area ADU Handbook (Official) — The regional ADU handbook published by the Association of Bay Area Governments: plain-language guidance on ADU types, state rules, design, costs, financing and renting out your unit, written for homeowners across the nine Bay Area counties. We recommend it to every client before the first design meeting. Category: Information and Resources
• Compact Excavator Rental — A 1.7-ton compact excavator that fits through a 36-inch gate, with a 12-inch and a 24-inch bucket, delivered to your site and picked up when you are done. Ideal for contractors digging footings and utility trenches in tight Bay Area backyards. Operator must be experienced; we walk you through the machine on delivery. Multi-day rentals get 10% off. Price: $395.00 Category: Site Work & Foundations
• Backyard ADU Open House Tour — Walk through three finished backyard homes in Oakland and Berkeley in one morning: a 420 sq ft factory-built studio, a two-bedroom detached cottage and a garage conversion. Meet the owners, the builder, the designer and a lender, ask what each one really cost, and see finishes up close. Saturday, November 14, 2026, 10:00 am to 1:00 pm. Start at our Oakland office; a shuttle runs between homes. Ticket includes the shuttle and coffee. Price: $15.00 Category: ADU Building & Remodeling
• ADU Care Plan — Keep your new backyard home in top shape after move-in. Twice a year a Longbeam technician inspects the roof, gutters, drainage, windows, plumbing, heat pump and water heater, replaces filters and smoke detector batteries, and sends a written report with photos. Members get priority service within two business days, 10% off repairs and help with warranty claims. Billed monthly; cancel anytime with 30 days' notice. Price: $89.00 Category: ADU Building & Remodeling