Folsom's ADU & space-conversion specialists. Income-generating backyard units, design + permits + build. CSLB #1094366. Free quote: (866) 797-7653. A1 Building Contractors LLC is a veteran-owned, licensed general contractor serving the greater Sacramento region. Every project starts with a review of the property, the local jurisdiction and the homeowner's goals.
Licensed California general contractor — CSLB #1094366, DRE #00898265.
Veteran-owned and based in Roseville, serving Sacramento, Placer and El Dorado counties.
Scope covers detached ADUs, attached ADUs, JADUs, garage conversions, home additions and custom homes.
Plans, permits, plan check and construction are coordinated in-house for Folsom ADU Specialists.
Typical detached ADU budgets run about $135K to $255K depending on size and site conditions.
Local guidance for Folsom ADU Specialists
A1 Building Contractors LLC helps Sacramento-area and Placer County homeowners evaluate design, permitting, site access, utilities, construction scope and realistic project costs before work begins. Each project is reviewed against the property, local jurisdiction and homeowner goals rather than a one-size-fits-all estimate.
For Folsom ADU Specialists, our team can explain practical options, likely approval steps and the tradeoffs that affect schedule and budget. Homeowners receive a clear path from initial feasibility through plans, permits and construction, with recommendations grounded in local building requirements and build conditions.
A productive first review considers available lot space, setbacks, access for construction, utility locations, desired square footage and long-term use. Those details help identify constraints early, compare appropriate project approaches and avoid spending on a design that does not fit the site or local rules. A1 then coordinates the applicable design and construction stages with clear decisions at each milestone.
ADU construction in Folsom, Sacramento County
If you own a home in Folsom, an accessory dwelling unit is one of the few ways to add square footage without buying land. We are a CSLB-licensed general contractor (#1094366) that specializes in ADUs rather than treating them as a side product. Typical all-in cost for a Folsom project runs $170K – $400K, and finished ADUs commonly add 22–35% to the property's value.
The first site visit exists to price the unknowns — Sacramento Municipal Utility District (SMUD) service upgrades and Sacramento-area sewer connection fees are the two line items that most often move a Folsom budget.
Typical all-in cost: $170K – $400K
State law limits local review of a complete ADU application to 60 days, and Sacramento County processes conforming ADUs ministerially — no public hearing
Junior ADUs (JADUs) — up to 500 sq ft carved out of the existing home, the lowest-cost path to a permitted unit · Attached ADUs — a permitted addition sharing one wall with the main house, useful on narrower Folsom lots · Design-Build — architectural plans, structural engineering and construction from one licensed Sacramento County contractor
Building an ADU in Folsom means working to Sacramento County and local Folsom requirements on top of California's statewide ADU law. Here is what shapes a project on a typical Folsom lot.
A1 Building Contractors handles the Folsom submittal, plan check corrections and inspections in house, so you are not coordinating between an architect, an engineer and a builder who each blame the other for a delay. We confirm setbacks, lot coverage, utility routing and fire access on the site walk, before a proposal is written.
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 are capped at 1,200 sq ft; attached units at 50% of the primary home
Impact fees are waived statewide for ADUs under 750 sq ft, which is why many Folsom projects land in the 700–749 sq ft range
Rear and side setbacks for a detached ADU are 4 ft; converted garages can keep their existing footprint
Services offered locally: Junior ADUs (JADUs) — up to 500 sq ft carved out of the existing home, the lowest-cost path to a permitted unit · Attached ADUs — a permitted addition sharing one wall with the main house, useful on narrower Folsom lots · Design-Build — architectural plans, structural engineering and construction from one licensed Sacramento County contractor · Permit Management — full submittal and correction handling with Sacramento County Planning & Environmental Review
Local average ADU investment: $170K – $400K
Common questions about ADUs in Folsom
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.
How we deliver ADU projects in Folsom
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
Why homeowners choose A1 for ADU construction in Folsom
A1 Building Contractors LLC is a veteran-owned, CSLB-licensed general contractor serving the greater Sacramento region. 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