ADU Project Coordination Across the West

Most ADU projects in California, Oregon, Washington, Nevada & Arizona land between $150,000 and $400,000 depending on size, whether it is detached or a garage conversion, site conditions, and finish level. Factory-built ADUs typically cost 10–25% less than fully site-built units because the structure is assembled in a controlled environment. The biggest cost variables are utility trenching distance, foundation requirements on sloped lots, and local impact fees. Homeland provides a line-item estimate after a free lot review, so you know the true all-in number — not just the base structure price.

Yes. Every ADU requires a building permit, and most jurisdictions also require separate electrical, plumbing, and mechanical permits. The good news: state law across California, Oregon, and Washington now requires cities to allow ADUs on most single-family lots and to approve compliant applications within set timelines (60 days in California). Homeland prepares the complete permit package, submits it, and handles all plan-check corrections, so you never have to visit the counter yourself.

Plan on 6–12 months total. Design and permitting usually take 2–4 months depending on how busy the local building department is. Construction takes 4–6 months for site-built units, or as little as 8–12 weeks for factory-built ADUs since site work and factory fabrication happen simultaneously. Weather, inspection scheduling, and utility company lead times are the most common delay sources, so those allowances are included in the schedule from the start.

In nearly all cases, yes — long-term rentals (30+ days) of permitted ADUs are allowed throughout California, Oregon, and Washington. Short-term rentals (Airbnb-style) are regulated locally and are restricted or banned for ADUs in many cities, so check your specific municipality before planning around nightly rates. A legal, permitted ADU in a strong rental market typically generates $1,500–$3,500/month, and lenders increasingly count that projected income when qualifying you for construction financing.

State law in California guarantees the right to build at least an 800 sq ft ADU on most single-family lots regardless of local lot-coverage rules, and detached ADUs up to 1,200 sq ft are common where lot size allows. Oregon and Washington have similar allowances that vary by city. Practical size is determined by setbacks (typically 4 feet from side and rear lines), existing structures, and utility locations. During our free feasibility review we overlay these rules on your actual parcel and tell you the maximum buildable envelope.

Plan-check corrections are normal — most first submittals receive at least one correction letter covering items like energy calculations, fire-separation details, or drainage plans. Because Homeland and its permit partners coordinate plan sets across West Coast jurisdictions, packages are prepared to each city's known requirements, which keeps correction cycles short. If corrections are issued, our design team responds directly to the plan checker, usually within days, at no additional cost to you. Outright rejections are rare for code-compliant ADU applications since state laws limit the grounds on which cities can deny them.

Factory-built (modular or manufactured) ADUs win on speed and price predictability: the unit is built indoors while your foundation and utilities are prepared, cutting total construction time roughly in half and eliminating weather delays. Site-built ADUs win on design flexibility — irregular lots, hillside foundations, or fully custom layouts. For flat, accessible lots, we usually recommend factory-built; for tight urban infill or sloped parcels, site-built often pencils better. Homeland coordinates both pathways, so our recommendation is based on your lot rather than a single product line.