Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Before
After
Before
After
Before
AfterFast, Reliable Home Additions & ADU Across Calabasas
A typical home addition or ADU in Calabasas runs $45,000-$130,000 for room and second-story work, while detached ADU construction usually falls between $90,000 and $220,000. Most projects take four to eight months from signed contract to final inspection, though gated communities here add a separate HOA review that extends the front end. Call (213) 221-0788 to schedule your free estimate - we’ll walk you through the actual approval sequence for your specific property.
We serve Calabasas from our Los Angeles office, with crews running daily to hillside neighborhoods and gated communities across the city. Dispatch and scheduling are coordinated locally, and our project managers know the difference between a standard city permit path and the dual-track approval required inside The Oaks or similar communities. That local knowledge keeps calendars realistic and prevents the half-finished additions we see left exposed when out-of-area contractors underestimate Calabasas’s review timeline.
Why Rowan Construction Group Sherman Oaks Is Calabasas’s Preferred Home Additions & ADU Company
We’ve completed additions and ADUs across Calabasas’s post-Woolsey rebuild areas and its original 1970s-1990s hillside stock. Our documented photo record on every visit means Calabasas homeowners see substrate conditions, framing progress, and fire-hardening details as the work proceeds - not after it’s covered.
Our Calabasas customers reference our written price discipline in reviews: the quote they received before work started matches the final invoice within a few percent, because no change proceeds without a signed change order. That’s Clause 1 of the Haven Standard, and it’s how we’ve operated since 2007.
Response time to Calabasas is typically same-week for initial site visits, with project managers routing from our Los Angeles office. For homeowners in The Oaks or other gated communities, we schedule the site visit to include HOA packet documentation - site photos, existing conditions shots, and preliminary elevation sketches - so the architectural review submission moves in parallel with city permitting.
We understand Calabasas’s specific conditions: the Very High Fire Hazard Severity Zone designation covering virtually all developable land, the thermal cycling that cracks older stucco on valley-facing slopes, and the Chapter 7A compliance that is baseline law here, not an upgrade option.
Our Home Additions & ADU Services in Calabasas
ADU Design & Permitting
Our ADU design and permitting service in Calabasas starts with a site feasibility study that flags both city and HOA constraints before we draw a wall. For properties in The Oaks, we prepare the architectural submittal packet - material samples, color chips, site photographs, and scaled drawings - concurrent with the city permit application for Chapter 7A fire-hardening compliance. A typical Calabasas ADU permit timeline runs eight to twelve weeks for city approval; we file the HOA packet simultaneously so the four-to-eight-week architectural review overlaps rather than serializes. Under Clause 1 of the Haven Standard, you’ll receive a written price for the full design, permitting, and construction scope before any work starts.
Garage Conversion ADU
Garage conversions in Calabasas run $30,000-$80,000 depending on whether the existing slab and roof structure meet current Chapter 7A standards. Many Calabasas garages built before 2008 lack ember-resistant venting and ignition-resistant siding - code requirements we identify during the initial site visit so the written quote includes full compliance, not a mid-project surprise. For hillside garages on Mulholland-adjacent streets, we assess whether the existing pad grading allows habitable-space conversion or requires structural modification. Every garage conversion quote includes the documented photo record of existing conditions, the written scope of Chapter 7A upgrades, and the flat price before construction begins.
New Detached ADU
New detached ADUs are our most requested Calabasas project type, typically ranging $90,000-$220,000. These structures must meet Chapter 7A from foundation to ridge: ember-resistant vents, enclosed eaves, ignition-resistant decking and siding, and Class A roofing. In The Oaks of Calabasas, the HOA Architectural Review Committee also controls exterior aesthetics - stucco color, roof profile, window grille pattern - which means we order no materials until both city and HOA approvals are in hand. Our crew completed a detached ADU in The Oaks where the HOA required standing-seam tile samples and stucco color chips before we could order the Class A roofing. We filed the architectural packet and city permit simultaneously, then scheduled the slab pour only after both sign-offs cleared. When the client asked mid-build to swap the approved decking for a lighter composite, we filed a written change order and a new AR sample rather than substituting in the field. An unapproved swap would have triggered a stop-work review and pushed the draw schedule weeks. The result was a Chapter 7A-compliant detached ADU with ember-resistant vents and enclosed eaves that passed inspection sign-off without a punch list delay.
Junior ADU & Interior Conversion
Junior ADUs and interior conversions in Calabasas often involve reconfiguring existing square footage within the main home’s envelope - a separate entrance and kitchenette carved from a ground-floor wing or attached garage. These projects still trigger Chapter 7A when they modify exterior walls or roofing, and HOA review applies if the work changes the visible exterior. For Calabasas homes with the Spanish tile and stucco exteriors common in 1980s tract-luxury developments, we match existing stucco texture and tile profile to maintain visual continuity, submitting samples to the HOA Architectural Review Committee when required. The written quote specifies whether the project is classified as a JADU (no separate conveyance) or full ADU, since that distinction affects parking requirements and utility metering under Calabasas’s municipal code.
Second Story Additions
Second story additions in Calabasas demand structural analysis of the existing foundation and framing, particularly on hillside pads where original grading may not have anticipated vertical expansion. We see this frequently in the city’s 1970s-1990s stock - large homes on canyon slopes with room to grow upward but footings designed for single-story loads. Our structural assessment is included in the initial site visit, with findings documented in the photo record and written into the scope before pricing. Second story work also requires full Chapter 7A compliance on the new exterior and often triggers HOA review for roofline and massing changes. We sequence these approvals before lifting walls, never after.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Before
AfterTrusted Brands We Service in Calabasas
Rowan Construction Group sources across fifty-plus vetted brands, giving Calabasas homeowners honest material numbers rather than inflated allowances. For window packages in Chapter 7A-compliant additions, we regularly specify ES Windows and ECO Window Systems - both offer fire-rated and impact-resistant lines that satisfy California Building Code requirements while meeting the aesthetic standards of Calabasas HOA committees. For roofing, we specify GAF and Owens Corning Class A assemblies. Our written quotes name the actual brand and product line, not a generic allowance, so the price you compare is the price we build to. Local supplier relationships mean material lead times don’t extend our Calabasas project schedules beyond the approval windows we’ve already built in.
Common Home Additions & ADU Problems We See in Calabasas Homes
- Ordering Chapter 7A materials before HOA Architectural Review Committee approval. Contractors who buy ember-resistant vents, ignition-resistant siding, or Class A roofing ahead of the AR submittal often eat the cost of re-review or material swaps when a sample isn’t approved. We order nothing until both city and HOA sign-offs are in hand.
- Underestimating the HOA review overlap with city permitting. The four-to-eight-week architectural review in Calabasas gated communities runs parallel to city processing, but out-of-area contractors frequently sequence them serially or ignore the HOA track entirely. We build both timelines into the project calendar from day one.
- Field substitutions without written change orders. Swapping an approved window, stucco color, or decking material mid-build - even for a “better” option - triggers a Calabasas stop-work review and stalls inspection sign-off. Our crews carry the approved spec on-site; any client request goes through a signed change order and new AR submission before installation.
- Thermal cycling damage on older stucco and mortar. Calabasas’s valley-facing slopes see 100°F-plus summer days with sharp overnight drops, causing premature cracking in original stucco and mortar joints. We assess substrate condition during the initial site visit and specify appropriate lath, membrane, and expansion joint details in the written scope - not as a change order discovered mid-project.
Pricing for Home Additions & ADU in Calabasas, CA
Home additions and ADUs in Calabasas carry a dual-track approval burden that affects timeline but not our pricing structure: the written flat price, delivered before any work starts, covers the full scope including both city and HOA submission cycles. Below are the ranges we see for typical Calabasas projects.
| Project Type | Typical Range in Calabasas |
|---|---|
| Home Addition (room or second story) | $45,000 - $130,000 |
| ADU Construction (new detached) | $90,000 - $220,000 |
| Garage Conversion ADU | $30,000 - $80,000 |
What moves a project within these ranges: foundation requirements (hillside pads versus flat lots), Chapter 7A material specifications, utility extension distances, and whether the property sits inside a gated community requiring HOA architectural review. Every quote from Rowan Construction Group is a flat price with written scope and written warranty - never a “call for pricing” placeholder. Bring a competitor’s written estimate and we’ll review it line by line at no charge. Call (213) 221-0788 for your free estimate.
We Also Serve Cities Near Calabasas
Our crews run daily to Calabasas and surrounding communities including West Hills, Canoga Park, Tarzana, and Encino. Each city’s approval environment differs - Los Angeles city permitting versus Calabasas’s Chapter 7A and HOA dual track - and our project managers route the right expertise to the right jurisdiction. Whether you’re in the Calabasas hills or the flatter Valley-adjacent neighborhoods of our Home Additions & ADU service area, the written price before work starts and the documented photo record on every visit apply the same way.
Serving Calabasas, CA - Our Local Coverage Area
We’re based in the Calabasas 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 - Home Additions & ADU in Calabasas
Yes. The Oaks of Calabasas requires separate Architectural Review Committee approval for any exterior modification, including new detached ADUs, garage conversions with visible changes, and second-story additions. We submit material samples, color chips, site photos, and architectural drawings to the HOA concurrent with the city permit application so the two review cycles overlap rather than stack. Call (213) 221-0788 to schedule your free estimate - we’ll review your specific property’s HOA requirements during the initial site visit.
Calabasas sits entirely within a Very High Fire Hazard Severity Zone, making California Building Code Chapter 7A - ember-resistant venting, ignition-resistant siding and decking, enclosed eaves, Class A roofing - legally mandatory for all new construction and substantial remodels. This is not an upgrade option; it’s baseline code that must pass inspection before occupancy. Our written quotes specify the exact Chapter 7A assemblies for your project, with brand names and product lines, so you know what you’re paying for before construction starts.
City permitting for a Calabasas addition or ADU typically runs eight to twelve weeks; HOA Architectural Review Committee approval in gated communities like The Oaks adds four to eight weeks. We file both applications simultaneously and schedule no construction activity until both are cleared, preventing the exposed, half-finished additions we see when contractors start at city sign-off and hope the HOA follows. Call (213) 221-0788 for a timeline specific to your property and project type.
Any material substitution - window style, stucco color, decking product - requires a written change order and new HOA Architectural Review Committee submission before installation. Field substitution without approval triggers a stop-work review in Calabasas gated communities, stalling the draw schedule and inspection sign-off by weeks. Our crews work from the approved spec sheet on-site; if you request a change, we file the paperwork and wait for sign-off before the swap occurs. The 365-Day Done Right Promise covers our work, but it doesn’t override HOA approval requirements - we handle both.
Many can, but they require Chapter 7A retrofit of exposed elements as part of the addition scope. Open eave soffits must be enclosed; untreated wood decking must be replaced with ignition-resistant material; and any new roofing must meet Class A standards. We assess existing conditions during the initial site visit, document them in the photo record, and specify required retrofits in the written scope and price before construction begins - not as a surprise discovery after walls are open. Call (213) 221-0788 for a free assessment of your specific home.
Ready to add space or build an ADU? Call (213) 221-0788 to schedule your free estimate. We’ll deliver a written flat price with full scope, timeline, and warranty before any work starts - that’s Clause 1 of the Haven Standard, and it’s how we’ve completed 4,000-plus projects since 2007.
Written by Grant Rowan, Owner at Rowan Construction Group, serving Calabasas since 2007.