







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 Tarzana
A room addition in Tarzana runs $180 – $420 per square foot depending on whether you’re building out, up, or converting an enclosed patio. The job typically takes 8 – 14 months from first plan review to final inspection, and the price you approve before work starts is the price you’ll see on the final invoice. That’s how we work at Fielding ADU Builders, and we’ve been doing it this way under The Garrison Standard since 2006.
We’re the Room Addition Contractor team serving Tarzana homeowners who want a second bedroom, a primary suite, a den, or a full second-story addition. We know the Tarzana Community Plan, the LADBS Van Nuys plan check process, and what a 1950s slab foundation on a half-acre Vanalden Avenue lot actually looks like underneath. Call (361) 315-4177 and a live person answers. No voicemail queue. Reed Calloway runs our crews, and he’s direct about what a Tarzana addition will cost and how long it’ll take.
Why Fielding ADU Builders Is Tarzana’s Preferred Room Addition Contractor Company

Tarzanans have already done the homework. They walk into our first meeting with setback questions, Title 24 energy report questions, and a suspicion that the last contractor lowballed the permit scope. We answer every one of those questions in writing before a single nail is driven.
We’re independently owned and operated inside the Garrison Partners family, and we hold ourselves to The Garrison Code: show up in the window, price in writing, build by the book, leave it clean, stand behind it for a year. That last part is the 365-Day Done Right Promise. If something fails within that year, we come back and make it right at no charge. It’s spelled out on paper, not promised over a handshake.
Every crew member on a Tarzana job is background-checked and shows up in uniform. You know exactly who’s on your property from day one. And when you call (361) 315-4177 at noon or midnight, a live person picks up.
We know Tarzana’s blocks, not just its zip codes. The R1 lots off Reseda Boulevard, the older ranch homes near Wilbur Avenue, the cul-de-sacs west of Tampa. We know where the sewer laterals run, where the setbacks pinch, and where a planning review will flag a second-story wall height before LADBS even opens the plans.
Modular Home Addition in Tarzana
Modular Home Addition in Tarzana means building your new space as factory-built wall panels, roof trusses, or full volumetric modules that arrive on a truck and get set in place with a crane. We’ve used Abodu, Cover, and Dvele systems on Tarzana lots where conventional stick framing would take months longer and cost more in labor.
A modular room addition in Tarzana runs $220 – $380 per square foot before site work, foundation, and permit fees. The factory builds to Title 24 energy standards, which saves you a correction cycle at LADBS Van Nuys because the envelope details are pre-engineered.
Prefab Wall Panel Additions
For single-story additions on compact Tarzana lots, prefab panels get framed, sheathed, and insulated in a controlled factory. They arrive flat-packed, and we set them in a few days instead of framing for weeks. The fit and finish are consistent because the factory doesn’t deal with Tarzana’s dusty summer winds on an open job site.
Volumetric Module Additions
When we add a primary suite off a Tarzana ranch, a volumetric module built by Abodu or Cover arrives with drywall, electrical, and plumbing rough-ins already done inside. This cuts on-site time significantly. The module lifts over the existing roofline and sets onto a prepared foundation we’ve already permitted and poured.
Home Addition Plans in Tarzana

Home Addition Plans in Tarzana are not a formality. They’re the difference between a project that starts in eight weeks and one that stalls for six months. Tarzana sits under the Tarzana Community Plan, which imposes R1 setback, height, and coverage rules that Los Angeles neighborhoods with higher-density zoning don’t face.
Expect $6,000 – $14,000 for a full architectural plan set, structural engineering, Title 24 energy report, and site plan for a standard Tarzana room addition. That’s before permit fees. If your lot is on a slope or in a fire hazard zone, add a soils report and WUI materials review.
Site Plan and Setback Review
We start with a survey and a site plan that respects Tarzana’s side-yard and rear-yard setback requirements. Skip this, and LADBS Van Nuys rejects the plan check. A rejected first submittal costs four to six weeks and triggers a second plan-check fee.
Architectural and Structural Plan Sets
The plan set shows foundation, framing, roof, electrical, plumbing, and Title 24 compliance. For a Type V wood-frame addition, the structural engineer specifies footings, shear walls, and roof connections. We’ve seen too many Tarzana homeowners pay a drafter $2,000 for plans that won’t pass LADBS because there’s no structural calc package attached.
Trusted Brands We Service in Tarzana
We work with the systems Tarzana homeowners are already researching. That includes Abodu and Cover for modular room additions, Dvele for high-performance prefab, and James Hardie siding for conventional builds that need to look right on a 1960s ranch without the stucco patch peeling in Tarzana’s dry summers. If you’ve already talked to a prefab company and they handed you plans, bring them in. We’ll tell you honestly what works with your lot, what the local utility hookups will add, and whether a conventional build pencils out cheaper. We keep a working knowledge of lead times from each manufacturer so you’re not waiting on a backordered panel package with a hole in your roof.
Common Room Addition Contractor Problems We See in Tarzana Homes
- Plan check rejections from the Tarzana Community Plan review. A second-story addition that looks fine to the naked eye gets flagged because the side-yard setback on an R1 lot is tighter than the homeowner assumed. That’s a six-week delay the minute LADBS stamps “corrections required.”
- Skipping the soils report on sandy-silt lots. Tarzana’s soil near the Santa Monica Mountains runs variable. A 1950s foundation that held fine for seventy years doesn’t mean a new 400 sq ft addition can sit on the same undersized footing. The soils report tells us before we pour, not after the slab cracks.
- Treating an enclosed patio like a cheap square-footage grab. Tarzana homeowners see a covered patio and think “room.” But an enclosed patio conversion is still a room addition under Title 24, still needs an architectural plan set, and still costs $180 – $300 per square foot. It is not a screened-porch upgrade.
- Underestimating the LADBS plan check timeline. The room addition plan check at Van Nuys runs two to three correction cycles on a standard Tarzana project. That’s 6 – 10 weeks of back-and-forth. Contractors who tell you “permits take two weeks” are setting you up for a voided schedule and a change order when the real timeline lands.
Pricing for Room Addition Contractor in Tarzana, CA
Here’s what a room addition actually costs in Tarzana right now, based on the work we’ve priced this year. A single-story 400 sq ft primary suite addition runs $72,000 – $168,000 all-in depending on finish level, foundation condition, and whether you choose modular or stick-framed. A 600 sq ft second-story addition runs $150,000 – $300,000, with the higher end reflecting structural steel, shear wall upgrades, and a full re-roof. Enclosed patio conversions run $45,000 – $90,000. Plan sets and engineering run $6,000 – $14,000, and LADBS permit fees add another $4,000 – $9,000 depending on valuation. We don’t give a fuzzy verbal estimate and then “figure it out later.” The price goes in writing before any work starts, and the number you approve on day one is the number on the final invoice. Call (361) 315-4177 for a free, written, line-item estimate.
We Also Serve Cities Near Tarzana
Our crews work throughout the west San Fernando Valley. If you’re in Encino, Reseda, Woodland Hills, or Canoga Park, we bring the same written-price-first approach and the same 365-Day Done Right Promise. We’re a Room Addition Contractor in Tarzana first, but our trucks and our permits are on the road across the Valley every week. Call (361) 315-4177 and we’ll tell you if your lot’s in our standard service area.
Serving Tarzana, CA - Our Local Coverage Area
We’re based in the Tarzana 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 Tarzana
Yes, in most cases. Tarzana’s low-density R1 lots are governed by LAMC 12.21 A.24 and the Tarzana Community Plan, which means a room addition that increases floor area or height typically triggers a planning review before the LADBS building permit is issued. If your addition stays within the setback and coverage limits, it’s an administrative review. If it doesn’t, you’ll need a variance or a discretionary approval, which adds months. Call (361) 315-4177 and we’ll tell you which path applies to your lot before you spend a dollar on plans.
Plan on 8 – 14 months. The honest breakdown: 6 – 10 weeks for LADBS plan check at Van Nuys with two to three correction cycles, 2 – 4 weeks for Tarzana Community Plan review, 2 – 4 months for construction on a single-story addition, and 4 – 6 months for a second-story. Prefab and modular systems shave 4 – 8 weeks off the construction phase. Anyone quoting you four months total is skipping the permit process. Get a written timeline with your written price by calling (361) 315-4177.
Foundation surprises. A 1950s slab with a failed sewer lateral underneath, like the one we found on Vanalden Avenue, forces a deepened footing redesign and a plumbing scope change. The other big one is a soils report that comes back worse than the preliminary assumption. That’s why we recommend the soils report up front. Our written price covers the work we can see and the work the report tells us to expect. Change orders only happen when the ground itself changes the job. Call (361) 315-4177 for a written estimate that names the assumptions we’re pricing against.
Yes. Tarzana lots work well with Abodu, Cover, and Dvele modules, especially on rear-yard additions where a crane can set the module without touching the existing house. The Tarzana Community Plan doesn’t prohibit prefab; it regulates the same setbacks, height, and design standards that any addition faces. Prefab often saves 4 – 8 weeks on framing and drywall because the factory build runs parallel with your foundation work. We’ll match the build method to your budget and lot. Call (361) 315-4177 for straight answers on which system fits your property.
Often, yes. Tarzana’s soils range from sandy-silt on the flats to more variable conditions on slope-adjacent lots near the Santa Monica Mountains. LADBS will require a soils report if your addition sits on a slope, if the existing foundation shows settlement, or if the project exceeds certain size thresholds. On flat lots with a clean foundation history, a standard footing design may not need one. We’ll tell you which applies to your address before you spend $4,000 on a report you may not need. Call (361) 315-4177.
Written by Reed Calloway, Owner at Fielding ADU Builders, serving Tarzana since 2006.








