An ADU in Oak Park answers two problems at once: somewhere for family to live, and an asset that earns on its own. A1 Building Contractors is a veteran-owned, CSLB-licensed (#1094366) design-build firm that handles the plans, the engineering, the permit submittal and the construction in-house. Oak Park ADU builds land around $145K – $295K once permits, utilities and finishes are counted — a 20–35% bump against a $465,000 median home value.
Typical all-in cost: $145K – $295K
State law limits local review of a complete ADU application to 60 days, and Sacramento County processes conforming ADUs ministerially — no public hearing
Detached ADUs — freestanding one- and two-bedroom units up to 1,200 sq ft, sited to Oak Park setbacks · Home Additions — bedroom, bath and primary-suite additions for Oak Park homeowners who want space without a second unit · Design-Build — architectural plans, structural engineering and construction from one licensed Sacramento County contractor
Neighborhoods served: Sacramento, Oak Park core, Surrounding Sacramento County properties
Typical property value increase: 20–35%
How we deliver ADU in Oak Park, CA
Every project runs through the same five-stage process, so you know what happens next and what it costs before construction starts. We handle design, engineering, jurisdictional plan check and construction under one contract, which keeps the schedule and the budget with a single accountable team.
Stage 1 — Site walk and feasibility: setbacks, utilities, easements and lot coverage reviewed on site
Stage 2 — Fixed-scope proposal: line-item pricing with permits, utility connections and finishes included
Stage 3 — Design and engineering: architectural plans, Title 24 energy calcs and structural engineering
Stage 4 — Permitting and plan check: submittal, corrections and approvals handled by our office
Stage 5 — Construction and closeout: weekly updates, final inspection, certificate of occupancy and warranty
Common questions about ADU in Oak Park, CA
The three questions homeowners ask most, answered plainly. Pricing reflects 2026 Sacramento-region construction costs including permits, utility connections and standard finishes.
How much does an ADU cost? Most detached ADUs land between $135,000 and $255,000 all-in, depending on size and site conditions.
How long does it take? Design and permitting typically run 3–5 months; construction runs 4–7 months after permits are issued.
Do you handle permits? Yes — plan check submittal, corrections and inspections are managed in house at no extra hourly cost.
Can I rent it out? California state law allows ADUs to be rented at 30-day-plus terms in every jurisdiction we build in.
Why homeowners choose A1 for ADU in Oak Park, CA
A1 Building Contractors LLC is a veteran-owned, CSLB-licensed general contractor based in Roseville, CA. We design, permit and build ADUs, garage conversions, home additions and custom homes across the Sacramento region, with transparent line-item pricing and a single point of contact from first site walk to final inspection.
CSLB #1094366 General Contractor · DRE #00898265 Broker
Serving Sacramento, Placer, El Dorado, Yolo and Sutter counties
In-house design, permitting, plan check and construction
4010 Foothills Blvd Ste 103-155, Roseville, CA 95747