ADU Contractors Near Me

The average cost to build an ADU ranges from $150 to $400+ per square foot, with total costs typically falling between $100,000 and $300,000 depending on the region and build type.

Soft costs, including architectural design, engineering, permits, and impact fees, can account for 10% to 20% of the total project budget.

California's AB 68 and AB 881 mandate that local agencies must approve ADU applications within 60 days and limit setbacks to 4 feet for side and rear yards.

In Florida's Miami-Dade and Broward counties, ADUs must comply with High-Velocity Hurricane Zone (HVHZ) standards, requiring impact-rated windows and doors to withstand 175 mph winds.

Massachusetts' new statewide law allows by-right ADUs up to 900 square feet or 50% of the primary dwelling's size, whichever is smaller.

The rest of it, in plain terms

• Oregon's HB 2001 and Washington's recent legislation have eliminated owner-occupancy requirements for ADUs used as long-term rentals.
• Under the International Residential Code (IRC) Appendix BC, an ADU must have a separate entrance, independent egress, and proper fire separation from the primary dwelling.
• Site preparation, including grading, foundation work, and trenching for new utility connections (water, sewer, electrical), often adds $10,000 to $30,000 to the baseline construction cost.
• The typical timeline for an ADU project is 6 to 12 months, split between design/permitting (2-6 months) and active construction (4-6 months), subject to local backlogs and supply chain availability.
• California's AB 1033 allows municipalities to opt-in to a framework where homeowners can sell their ADU separately from the main house as a condominium.

Figures below are researched market numbers for budgeting and comparison. They are not quotes. Final pricing depends on your site, your jurisdiction, finish selections, foundation and utility distance.

• Low-End/Garage Conversion Total Cost: $100,000 - $200,000
• Mid-Range/Detached New Build Total Cost: $200,000 - $300,000+
• Soft Costs (Permits, Design, Fees): Typically 10% - 20% of total budget.
• Site Prep & Utilities: Often adds $10,000 - $30,000 depending on trenching distance and existing infrastructure.

ADU rules are set locally and change often. These are the provisions that most commonly control the outcome. Verify against your own jurisdiction before you design anything.

• California AB 68 / AB 881: Removes minimum lot size requirements, limits local setbacks to 4 feet, and streamlines the approval process for ADUs and JADUs.
• California SB 9: Allows urban lot splits and up to two units per parcel in single-family zones.
• California AB 1033: Allows homeowners to sell ADUs separately from the primary residence as condominiums (if adopted by local municipality).
• Florida (Miami-Dade/Broward): ADUs must meet High-Velocity Hurricane Zone (HVHZ) provisions of the Florida Building Code, requiring impact-rated windows/doors and 175 mph wind resistance.
• Massachusetts (Statewide ADU Law): Allows by-right ADUs up to 900 sq. ft. or 50% of the primary home's floor area (whichever is smaller) and prohibits owner-occupancy requirements.
• Washington (RCW 36.70A.680/681): Requires cities to allow two ADUs per lot, removes owner-occupancy mandates, and caps impact fees.
• Oregon (HB 2001): Requires cities over 10,000 to allow ADUs and duplexes in single-family zones and removes owner-occupancy requirements for long-term rentals.
• IRC (International Residential Code) Appendix BC: Requires a separate exterior entrance or common hallway entrance, fire separation, and independent egress for ADUs.

Most homeowners choose an ADU contractor the same way they would choose a bathroom remodeler, and that is where the trouble starts. An ADU is not a remodel. It is a complete dwelling with its own foundation, its own utility connections, its own energy compliance path and its own certificate of occupancy. A contractor who has built forty kitchens and zero ADUs will learn on your project, at your expense, and the learning shows up as change orders.

Ask for three completed ADUs in your jurisdiction, with addresses and permit numbers. Permit numbers are public record and take ten minutes to verify. A contractor who has genuinely built in your city will hand them over without hesitation. One who deflects is telling you something. Also ask who pulls the permit: if the contractor asks you to pull an owner-builder permit, that shifts liability and warranty obligations onto you and is worth refusing.

Compare bids on scope, never on the bottom line. Two ADU bids twenty thousand dollars apart usually describe two different projects. The cheaper one commonly excludes site work, utility trenching, impact fees, the energy compliance report, or the finish allowances that get spent regardless. Ask each bidder to price the same written scope and the spread narrows dramatically.

Eight questions that separate an ADU builder from a remodeler

Most pages on this subject put the cost behind a contact form. The reasoning is understandable and the result is that you cannot budget, cannot compare, and cannot tell whether a bid is reasonable until you have already given up your phone number to three companies.

We publish the figures instead. They are researched market ranges rather than quotes, and site conditions will move them more than any other factor, but a range you can plan against beats a call-back you have to wait for. The constraints that decide feasibility — setbacks, height, utility distance, site access — are stated up front for the same reason. If your project is not viable, that is worth knowing on the first visit rather than the third phone call.

Factory production windows move with queue depth, material lead times and seasonal demand. We quote the current window rather than a fixed promise, because anyone promising a specific delivery date months out without seeing the factory schedule is guessing. Permitting is usually the longer pole: in ministerial states the review clock is defined by statute, while in discretionary jurisdictions it can run considerably longer.

The sequence that controls your schedule is site plan, permit submittal, plan check and corrections, permit issuance, factory slot, delivery and set, then utility connection and final inspection. Factory build time overlaps permitting only if you commit to the slot before permits are issued, which carries its own risk.