ADU Permitting Process in Sonoma County
ADU Permits. Handled Start to Finish.
Northern Hills Construction manages the ADU permitting process across Sonoma County - from the first lot check to the issued permit. California law requires ADUs to be approved ministerially: no discretionary hearings and no neighborhood vote. As a licensed general contractor based in Guerneville, our father-son team prepares your plans, submits the application, and answers every plan-check comment, so your project keeps moving.
How ADU Permits Work
Common Questions
Do I need a permit for an ADU? Yes - every ADU needs a building permit, but approval is ministerial under California law: plans that meet the objective standards are approved without discretionary hearings. We submit a complete application so review stays on track.
Our proven 3-step method for taking your ADU from first lot check to issued permit.
1. Feasibility & Code Check
Every permit starts with your lot: zoning, setbacks, access, and utilities. Under current Permit Sonoma standards, a new detached ADU can be up to 1,200 square feet and 35 feet tall, with 4-foot side and rear setbacks - we confirm exactly what your lot allows first.
2. Plans & Application
We prepare the construction drawings and the application package, then submit to your local building department - Permit Sonoma for unincorporated lots, or your city's building division. Complete submittals avoid correction cycles.
3. Review to Permit
ADU review is ministerial under California law - no discretionary hearings. We track the review, answer plan-check comments, and keep it moving until your permit is issued.
Permitting is its own phase of work, and it is where ADU projects are won or lost. Here is what our team handles for every project, from backyard cottages to garage conversions.
Feasibility & Site Review
Before you invest in plans, we check your lot against state law and local standards - zoning, setbacks, height, lot coverage, and utility access. You get a clear answer on what your property allows.
Applications & Submittals
We assemble the full permit package - construction drawings, site plan, Title 24 energy documents, and required forms - and submit it to Permit Sonoma or your city's building department.
Plan Check to Approval
We manage the review with the building department, respond to plan-check comments, and revise the drawings until your permit is issued. Then we schedule the build and every inspection.