A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Room Addition Contractor Across Hidden Hills
A room addition in Hidden Hills, CA typically runs $180 – $380 per square foot depending on foundation work, finish level, and how the equestrian zoning shapes your buildable envelope. Most Hidden Hills additions take 4 – 8 months from design review to final inspection. If you’re on a one-acre parcel off Round Meadow Road or Long Valley Road and want to know exactly what your addition will cost before signing anything, call (361) 315-4177.
We’re Fielding ADU Builders, the Room Addition Contractor team inside the Garrison Partners family. We work in Hidden Hills weekly, and we’ve learned that this city works differently than Calabasas, Westlake Village, or anywhere else in the 91302 corridor. Setbacks, ridgeline rules, equestrian zoning, and a design review board that reads every plan line by line. We scope around all of it from day one, and we put the price in writing before a single footing is dug.
Why Fielding ADU Builders Is Hidden Hills’s Preferred Room Addition Contractor Company
Hidden Hills homeowners don’t bring us in to compare six bids. They bring us in because a previous contractor either failed the design review, moved the price after demolition, or never showed up with a permit. The Garrison Standard exists for exactly that reason. Every project gets a written price before any work starts, and every job is covered by a written one-year guarantee. If something fails inside 365 days, we return and correct it at no charge.
Reed Calloway leads our team, and he’s built his reputation on straightforward pricing and permitted work done by the book. We don’t skip the soils report. We don’t tell you to “just start and we’ll figure out the permit later.” Hidden Hills requires a different kind of contractor, and that’s who we are. Our crews are background-checked, uniformed, and we answer the phone with a live person 24 hours a day. No voicemail, no callback queue.
We’ve framed additions on 1960s ranch homes off Jed Smith Road, handled in-law suites near the Las Virgenes entrance, and worked through equestrian setbacks that most contractors never even check. Local knowledge here isn’t a nice-to-have. It’s what keeps your project from stalling at the city counter.
Home Addition Plans in Hidden Hills
Home Addition Plans in Hidden Hills aren’t something you can pull from a generic Los Angeles template. The city applies hillside and ridgeline design rules to any new gross floor area, and the equestrian minimum of one acre means your addition has to work around existing stables, corrals, and riding trails. A plan set that ignores those constraints gets redlined, and suddenly you’re three months behind a schedule you never had in writing.
What the job involves: a site survey tied to the city’s one-acre lot map, a soils and structural assessment, an architectural set drawn to Hidden Hills design review standards, and a submittal package that includes roof pitch, massing, and exterior material callouts. Homeowners in Hidden Hills should expect to pay $4,000 – $12,000 for a complete plan set and structural engineering, depending on lot slope and scope. Larger additions with retaining walls or hillside footings will run higher.
Design Review Submittal
Hidden Hills reviews additions for massing, color, and roof form. That’s a hurdle, not a suggestion. We package the submittal early so your plan arrives at the city already aligned with what their reviewers expect. Fewer redlines means a calendar that holds.
Site Assessment and Soils
Hidden Hills has clay-heavy soils and sloping lots, especially on the western edge near the ridgelines. Footing depth and drainage get driven by what the soils report finds, not by a per-square-foot guess. We bring in geotechnical work before pricing, not after demolition.
In Law Suite Builders in Hidden Hills
In Law Suite Builders in Hidden Hills do more than add a bedroom and a sink. A proper in-law suite here means a separate entry, a kitchenette or full kitchen, and living space that functions independently of the main house. Hidden Hills zoning allows these as attached additions on one-acre parcels, but the floor area still counts toward the city’s design review and ridgeline rules.
Market pricing for an attached in-law suite addition in Hidden Hills runs $160,000 – $320,000, depending on finish level, structural work, and whether you’re tying into an existing slab or pouring new footings. The range is wide because a suite on a flat one-acre lot near Round Meadow Road is a very different build than one on a sloped parcel behind Las Virgenes Road.
Separate Entry and Motor Court Access
Most Hidden Hills in-law suites work best with their own door off the motor court or side yard. That layout keeps the suite private for an aging parent or adult child. We frame and finish those entries as part of the main addition, so they pass design review as one cohesive structure rather than a tacked-on afterthought.
Kitchenette and Plumbing Scope
Adding a kitchenette to an in-law suite means running new supply and drain lines, which on a 1960s slab home can mean cutting concrete. That’s a cost driver we write into the price before work starts. No one wants to hear about a plumbing change order after the walls are up.
Trusted Brands We Service in Hidden Hills
We build with James Hardie lap siding on most Hidden Hills additions because it holds up to the dry Santa Ana winds and meets design review’s preference for muted, earth-toned exteriors. We also work with prefab and modular platforms including Abodu, Cover, and Dvele when a homeowner wants a faster build path or a specific floor plan. Stocking local siding and trim in our Los Angeles yard means we can match existing board profiles on a 1960s ranch without waiting on a special-order shipment.
Common Room Addition Contractor Problems We See in Hidden Hills Homes
- Scoping without the one-acre minimum in mind. Contractors who treat Hidden Hills like a standard LA County lot price the job off the wrong buildable envelope. The addition ends up smaller than the client assumed, or the price moves once the survey comes back.
- Skipping design review until after signing. Plans get redlined for roof pitch, massing, or color after the homeowner has already committed. The calendar stretches, the client is locked in, and everyone is angry. We submit early and review-ready.
- Pricing off a generic per-square-foot number. Hidden Hills has real hillside drainage and soils conditions. Footing, retaining, and drainage costs surface only after demolition if the contractor never did a geotechnical review. That’s the most common way the number moves mid-job here.
- Building toward the horse turnout. The equestrian setback runs along the rear of many Hidden Hills lots. An addition that pushes back toward stables or corrals triggers a redesign. We pull additions forward on the lot, which adds engineering but avoids a city rejection.
Pricing for Room Addition Contractor in Hidden Hills, CA
A standard room addition in Hidden Hills runs $180 – $280 per square foot. That covers the foundation, framing, roofing, drywall, electrical, plumbing where applicable, and basic finishes. Higher-end work with custom millwork, an attached in-law suite, or hillside retaining runs $280 – $380 per square foot. Plan sets, structural engineering, and city fees add $15,000 – $35,000 on top. The drivers that move a Hidden Hills quote most: lot slope, distance to existing stables or corrals, roof pitch requirements under ridgeline review, and whether new footings tie into a 1960s slab or sit on virgin soil.
Call (361) 315-4177 for a free estimate. You’ll get a written price before any work starts, and that number is the number on the final invoice. No change orders handed to you at the door.
We Also Serve Cities Near Hidden Hills
While this page is written for Hidden Hills homeowners, our crews also take on room additions in Los Angeles, Long Beach, Anaheim, and Riverside. If you’re just outside Hidden Hills and planning an addition, call us. The same written-price standard and one-year guarantee apply everywhere we work.
Serving Hidden Hills, CA - Our Local Coverage Area
We’re based in the Hidden Hills area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About Room Addition Contractor in Hidden Hills
Yes. Hidden Hills requires design review and a ridgeline submittal before construction can begin, and the city’s equestrian zoning and one-acre minimum shape the buildable envelope. Without a survey and soils assessment first, any price a contractor gives you is a guess. We pull the survey and soils report before we quote a firm number, so your price reflects the actual envelope, not a generic per-square-foot estimate. Call (361) 315-4177 to start with the right scope.
Hidden Hills enforces a minimum one-acre lot size and most parcels are zoned for horses, which means the buildable area of your lot is not just the whole parcel minus the standard setbacks. Existing stables, corrals, and riding trail easements all push your addition forward or sideways. On one project off Round Meadow Road, the equestrian setback ran along the rear of the lot, so we pulled the addition forward rather than toward a horse turnout. That change added engineering but avoided a redesign. Call (361) 315-4177 and we’ll scope your lot against the equestrian map first.
A room addition in Hidden Hills is planned construction, not emergency repair. The realistic calendar is 1 – 2 months for survey, soils, and plan set, 1 – 3 months for design review and permitting, and 2 – 4 months of construction depending on scope. That’s 4 – 8 months total. Anyone promising same-day or emergency room-addition work is not being honest with you. Call (361) 315-4177 to get a written schedule for your specific project.
An in-law suite adds a separate entry, a kitchenette or full kitchen, and often a second full bath. That means more plumbing runs, more square footage, and more scrutiny under Hidden Hills design review because the massing increases. In-law suite additions in Hidden Hills typically run $160,000 – $320,000, while a plain bedroom-and-bath addition runs lower. If you’re weighing both, call (361) 315-4177 and we’ll walk you through the difference in writing.
The price moves when a contractor skips the geotechnical and soils review, ignores the equestrian setback, or chases a design review redline after you’ve already signed. Those are all Hidden Hills-specific failure modes. With our written-price policy, the number you approve on day one is the number on the final invoice. We absorb the engineering surprises because we did the site work first. Call (361) 315-4177 for a free estimate with the full site package behind it.
Written by Reed Calloway, Owner at Fielding ADU Builders, serving Hidden Hills with written pricing and the one-year Garrison Standard guarantee.
