A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Home Addition Contractor Across Hidden Hills
Adding square footage to a Hidden Hills home costs roughly $220 – $480 per square foot for a site-built addition, with most projects landing between $110,000 and $480,000 depending on scope. That is the honest range before anyone walks your property. Our crews know the Hidden Hills gate protocol, the equestrian-lot setbacks, and the city’s architectural design review process, which means the price we quote is the price you plan around. Call (903) 568-7222 to schedule a free estimate.
Hidden Hills is not a standard LA suburb. The city runs its own design-review process, enforces equestrian-lot standards that tighten the buildable envelope on many parcels, and requires a level of documentation most contractors never mention until the stop-work order arrives. We handle that from day one: written price, permit path mapped, review conditions understood before you commit a dollar.
Why Benson ADU Builders Is Hidden Hills’s Preferred Home Addition Contractor Company
Troy Eastman leads our team, and the reputation we have built in Hidden Hills comes from showing up with a plan in writing. Homeowners here are not first-time renovators. They have seen a neighbor’s addition stall for a year because the city’s architectural review caught something the contractor missed. Our process exists so that does not happen on your property.
Every project gets a written price before work starts, a written guarantee, and a 365-Day Done Right Promise. If something is not right within the full year after completion, we make it right. No fine print gymnastics. No “that was the other crew” deflection.
Our technicians are background-checked, arrive in uniform, and a live person answers the phone around the clock. When you are coordinating a second-story addition while living in the house, you need to reach a human who knows your project, not a voicemail loop.
We are also an Home Addition Contractor that brings something most Hidden Hills homeowners do not expect: access to prefab systems from Abodu, Cover, and Dvele alongside traditional site-built construction. That means we can show you two or three real build paths with real costs, not one take-it-or-leave-it bid.
Sunroom Addition in Hidden Hills
A sunroom addition in Hidden Hills typically runs $65,000 to $150,000, but the bigger variable is design review. Hidden Hills treats a sunroom as an architectural addition, not a minor patio enclosure, so it must clear the city’s design-review process before a building permit is issued. Homeowners who skip that step end up with a stop-work order and a redesign bill.
What the Design Review Actually Changes
The Hidden Hills architectural review looks at roofline continuity, exterior materials, window proportion, and how the addition relates to the existing structure and neighboring parcels. On equestrian lots, the reviewers also check that the addition does not encroach on required stable setbacks or horse turnout areas. We submit drawings that anticipate those conditions, which keeps the review from bouncing back twice.
Real Costs on a Hidden Hills Sunroom
The enclosure itself is usually $45,000 to $90,000. Foundation and site work adds $10,000 to $25,000. Design review fees, city permit fees, and LA County plan check typically add $4,000 to $9,000. If the sunroom needs to match an existing slate or clay tile roofline, material and labor costs climb fast.
Second Story Addition Contractor in Hidden Hills
We are a second story addition contractor serving Hidden Hills with a straight answer on cost: most second-story additions here run $150,000 to $320,000 for a 400 – 800 square foot addition. Hidden Hills compounds the price because the city’s design review and hillside grading standards often require structural engineering beyond what a flat-lot LA County project demands.
Working Around Equestrian Lots
Our crew recently completed a second-story addition on a half-acre equestrian property off Long Valley Road in Hidden Hills. The homeowners needed a guest suite above an existing single-story wing while keeping the horse turnout area undisturbed. We used James Hardie siding to match the community’s exterior material palette, scheduled deliveries through the Hidden Hills gate, and worked around the city’s design-review conditions. The final inspection cleared after we documented that the addition’s height and setback met both county code and the city’s equestrian overlay standards.
The Structural Reality
A second story adds dead load and live load to the existing foundation. In Hidden Hills, where many homes sit on expansive or hillside soils, that often means foundation retrofitting, shear-wall upgrades, or new footings. Budget $15,000 to $40,000 for structural work before finishes are even discussed. We put that number in the written estimate so there is no change-order surprise after demo.
Trusted Brands We Service in Hidden Hills
We build with and service systems from Abodu, Cover, and Dvele, which gives Hidden Hills homeowners researched, factory-engineered options alongside traditional site-built construction. These are real brands with public specs, third-party engineering, and warranty documentation you can verify yourself. We also source James Hardie cladding for additions that need to match Hidden Hills’ board-and-batten and wood-siding aesthetic. When a design review committee asks for material submittals, we already have them in hand.
Common Home Addition Contractor Problems We See in Hidden Hills Homes
- Skipping the Hidden Hills architectural design review. Homeowners who pull a county permit without city sign-off receive a stop-work order. The redesign alone often costs $8,000 to $20,000 and delays the project by months.
- Assuming standard LA County lot-coverage rules apply. Hidden Hills equestrian lots and hillside grading standards frequently shrink the buildable envelope. A second-story addition that fits on county paper may violate city height or setback conditions.
- Treating a sunroom or second-story addition like a quick prefab drop-in. Boxabl and Tuff Shed units can work for some ADU situations, but Hidden Hills site conditions and design review usually demand a custom or hybrid approach. We are upfront when a pure prefab path will not clear review.
- Discovering foundation issues after demo begins. Hillside and expansive soils in Hidden Hills can turn a clean addition into a structural retrofit. We order a soils report early and price the fix before the first wall comes down.
Pricing for Home Addition Contractor in Hidden Hills, CA
Here are the ranges we quote for Hidden Hills projects. A sunroom addition runs $65,000 to $150,000. A second-story addition runs $150,000 to $320,000 for most homes. A room addition or bump-out runs $80,000 to $200,000 depending on foundation work, finish level, and whether the space needs plumbing. A bathroom addition runs $45,000 to $95,000. A garage addition or conversion runs $55,000 to $130,000. What moves the number: the Hidden Hills design review conditions, structural engineering on your specific lot, finish selections, and whether we are working with a prefab system like Cover or Dvele versus a full site build. Call (903) 568-7222 for a written, line-item estimate. It is free.
- Sunroom addition: $65,000 – $150,000
- Second-story addition: $150,000 – $320,000
- Room addition or bump-out: $80,000 – $200,000
- Bathroom addition: $45,000 – $95,000
- Garage addition or conversion: $55,000 – $130,000
We Also Serve Cities Near Hidden Hills
Our crews also handle home addition projects in Hidden Hills and the surrounding metro: Los Angeles, Long Beach, Anaheim, and Riverside. Scheduling is coordinated from the brand’s Los Angeles office, with local crews dispatched directly to Hidden Hills job sites. Call (903) 568-7222 and we will let you know the next available estimator slot for your area.
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 Home Addition Contractor in Hidden Hills
Yes. Hidden Hills enforces a citywide architectural design review that must be completed and approved before LA County will issue a building permit for any home addition, including sunrooms and second-story additions. The review covers exterior materials, roofline, massing, and on equestrian lots, compliance with setback and horse-facility standards. Expect the review to add three to eight weeks to the front end of the project. Call (903) 568-7222 and we will map the exact review sequence for your parcel.
Yes, in most cases. Hidden Hills equestrian lot standards place protected setbacks around stables, arenas, and turnout areas, but a second-story addition over an existing single-story wing often clears review when the footprint does not encroach on those zones. The key is documenting height, setbacks, and drainage against both county code and the city’s equestrian overlay before submitting. We have done exactly this on Long Valley Road and similar equestrian parcels.
Plan on six to fourteen months total. The Hidden Hills design review adds three to eight weeks before permitting, LA County plan check adds four to eight weeks, and construction itself runs three to six months for a sunroom or room addition, and five to eight months for a second-story addition. Weather, material lead times, and review committee scheduling all move the calendar. We give you a written schedule with milestone dates, not a vague “we will be done when we are done.” Call (903) 568-7222 for a project-specific timeline.
Three specific triggers account for nearly every change order: foundation conditions discovered after excavation, Hidden Hills design review conditions that require material or design revisions, and homeowner finish selections that escalate after the contract is signed. Our written price includes a soils report, a structural review, and finish allowances, so the price holds. If something changes, you receive a written change order with a line-item cost before work proceeds. The free estimate at (903) 568-7222 includes this breakdown.
Sometimes. Abodu and Cover units can work for detached ADUs on flat lots with standard setbacks, but Hidden Hills design review and equestrian conditions often require a hybrid approach: a prefab shell combined with site-built foundation, exterior cladding, and roofline modifications. Mighty Buildings panelized walls can speed up a second-story addition, but the structural engineering and design-review documentation still need custom work. We are authorized with all three brands, so we can show you the honest trade-off: factory precision versus design-review fit. Call (903) 568-7222 to talk through which path clears Hidden Hills review on your lot.
Ready to price your addition? Call (903) 568-7222 now to schedule a free, written estimate with Benson ADU Builders. You will get real numbers, a real plan, and a contractor who already knows the Hidden Hills review process.
Written by Troy Eastman, Owner at Benson ADU Builders.
