Hollywood Hills Home Addition: Second-Story, Bump-Out, Or Master Suite — Built To The View
A home addition in Hollywood Hills is the most jurisdictionally complex residential project we do. A second-story over a 1958 Mid-Century needs a structural engineer to retrofit the existing post-and-beam to carry the new load. A bump-out off the kitchen needs a Baseline Hillside Ordinance review because you are touching the building envelope on a slope. A new master suite added to the rear of a Beachwood Canyon Spanish Colonial needs to respect the Mulholland Scenic Corridor view-protection rules if you are anywhere near the corridor. And every one of them needs CBC 7A fire-hardening, a Class A roof tie-in to the existing roof, and sometimes a neighbor-notification process under BHO §C view-impact rules. Half the additions we get called in to rescue were started by GCs who priced them like a flat Sherman Oaks job. NP Line Design has been designing in the hills since 2016 and building as a CSLB GC since 2023. We price the real number, in writing, before anything goes to LADBS.
What's actually different about a Hollywood Hills addition
Six jurisdictional and physical realities that shift the cost band:
- BHO grading and footprint caps. Any exterior wall move or roofline change on a slope over 15% triggers Baseline Hillside Ordinance review. The BHO caps how much footprint you can add, how tall the addition can go, and how much grading the project allows.
- HCR-SUD additional review. If the parcel is inside the Hillside Construction Regulation Supplemental Use District, you face a second layer of plan check covering haul routes, parking, and construction-impact mitigation.
- Mulholland Scenic Corridor Specific Plan. If the property is within the corridor (roughly 500 ft on either side of Mulholland Drive), you face additional design review and view-protection rules.
- Neighbor view protection under BHO §C. The Baseline Hillside Ordinance includes neighbor view-impact provisions for additions that would meaningfully block established views. We design around these from the first drawing.
- Structural retrofit on Mid-Century homes. Adding a second story to a 1958 post-and-beam means the existing posts need to be re-engineered or supplemented, the foundation needs to be checked, and the lateral system (shear walls or moment frames) needs new engineering.
- VHFHSZ Class A roof tie-in + CBC 7A exterior. The new roof has to be Class A, has to tie cleanly to the existing roof, and the new exterior walls have to be non-combustible or ignition-resistant.
Our process for a Hollywood Hills addition
One firm, one contract, from feasibility through final inspection. On an addition more than any other project type, the architect and the GC have to be the same company — because the structural retrofit, the BHO setback, and the view-axis preservation are decisions that happen at the drawing board, not at framing.
- Month 1 — Free feasibility walk. Netanel walks the property, reads the existing structural envelope, checks the BHO designation map, pulls the Mulholland Corridor and HCR-SUD overlays for the parcel, and sketches what is actually buildable.
- Month 1-2 — Geotech (if needed) + zoning letter + initial structural read.
- Month 2-5 — Architectural drawings + structural engineering + grading plan + view-axis study + neighbor-impact analysis. Fixed-price contract locked at the end of this phase.
- Month 5-9 — LADBS plan check + BHO review + HCR-SUD + Mulholland Corridor (if applicable) + LAFD signoff. Addition permitting on a hillside lot typically runs 16-24 weeks.
- Month 9-18 — Build. Demo + structural retrofit + framing + Class A roof tie-in + CBC 7A exterior + interior finish + final inspection.
A clean rear bump-out off a flat-pad portion of a hillside lot runs 6-8 months total. A second-story addition on a Mid-Century with full structural retrofit runs 12-18 months.
Cost band: what $180K-$600K+ actually buys
Real Hollywood Hills addition invoices from the last 24 months:
- $180K-$280K — bump-out tier. 200-400 sq ft single-story addition off the rear or side, modest exterior footprint change, no structural retrofit of existing house, standard Class A roof tie-in. Outpost Estates 1990s contemporary, 6-8 months total.
- $280K-$420K — master suite tier. 500-800 sq ft new master bedroom + bath + closet, structural engineering on existing wall, possible new foundation pour, full CBC 7A exterior, possible new HVAC zone. Beachwood Canyon Spanish Colonial, 9-12 months.
- $420K-$600K — second-story tier. 800-1500 sq ft new second floor, full structural retrofit of existing first floor (posts, foundation, lateral system), new staircase, full re-roof in Class A, exterior siding refresh to match new construction, possible solar + Title 24 compliance for the whole structure. Case Study Mid-Century, 12-16 months.
- $600K+ — second-story + complex hillside tier. Add caisson underpinning for the existing foundation, retaining work for new building envelope, Mulholland Corridor design review, custom premium finishes. 14-18 months.
Every line item priced. The structural retrofit hours, the BHO permit, the geotech, the view-axis study — all named.
Why view, neighbors, and structural retrofit are the real cost drivers
On a flat-lot addition, the cost is mostly square footage times a rate. On a Hollywood Hills addition, three different things move the budget more than square footage does:
- View-axis preservation, yours and your neighbor's. A second-story addition that blocks the downhill neighbor's Reservoir view will draw a BHO §C challenge and add 8-16 weeks. We run the view-axis study during architectural design so the form factor is settled before LADBS sees the drawings.
- Existing structural condition. A 1958 Mid-Century built with then-standard 2x6 framing and 4x4 posts cannot carry a second floor without significant supplementation. The structural retrofit is sometimes 25-35% of the total addition budget.
- Mulholland Scenic Corridor review. If your parcel falls inside the corridor, the design review process adds 12-20 weeks and constrains the form factor of the addition (height, massing, materials). We pull the corridor map at the feasibility walk so this is known from day one.
An architect-plus-GC under one roof is the only way to get all three of these decisions made at the drawing stage, not the framing stage.
Risk reversal: how we make a $400K addition safe to sign
Same model, scaled to addition risk:
- Phased contract: drawings + permits as Phase 1, build as Phase 2. You commit to the build only after the permits are in hand and the structural engineering is stamped. No surprise structural cost at month 8.
- Fixed-price after permits issued. The post-permit contract is line-item fixed-price.
- Permit pulled in NPLD's name. Including BHO grading, HCR-SUD, Mulholland Corridor (if applicable), and LAFD access.
- Change orders in writing, signed before work.
- One-year workmanship + 10-year structural warranty on retrofit and new framing.
- Lien releases at every draw.
Free feasibility walk to start. You get a real range, the BHO read, the Mulholland Corridor read, and a structural opinion on what the existing house can support — all without committing to a drawing contract.
Home Addition Questions Homeowners Ask About Home Addition in Hollywood Hills
Can I add a second story to my 1958 Mid-Century without rebuilding the first floor?
Usually yes, but the first-floor structural system needs supplementation. The existing posts and beams will be load-tested by the structural engineer, new shear walls or moment frames will be added for lateral resistance, the foundation will be checked and sometimes underpinned, and connections between old and new framing will be hardware-engineered. Plan on 25-35% of the addition budget going to structural retrofit on a Mid-Century. We tell you what the existing house can carry at the feasibility walk.
Will the BHO let me add 800 sq ft to my Hollywood Hills home?
Depends on lot slope, parcel size, and what is already built. The Baseline Hillside Ordinance caps allowed Residential Floor Area as a function of lot size and slope — steeper slopes get smaller caps. We pull your specific RFA cap at the feasibility walk before any design happens, so the addition is sized to what is actually buildable.
What is the Mulholland Scenic Corridor and is my property inside it?
The Mulholland Scenic Corridor Specific Plan covers parcels generally within 500 ft on either side of Mulholland Drive. Properties inside the corridor face additional design review for any exterior changes, with rules covering building height, massing, materials, and view protection from the corridor. The map is online, but the actual corridor boundary is parcel-specific. We pull your status at the feasibility walk.
Can my downhill neighbor block my second-story addition?
They can file a view-impact challenge under BHO §C if your addition meaningfully blocks an established view. The challenge does not auto-block the permit, but it triggers a discretionary review that can add 8-16 weeks and sometimes force form-factor changes. We run a view-axis study during architectural design and, where realistic, brief the affected neighbor before the permit application. This has saved us multiple BHO §C challenges over the past 4 years.
Do I need a geotech report for a home addition?
If the addition increases the foundation footprint on a slope over 20%, yes. If you are bumping out 200 sq ft over an existing slab, sometimes no. We make the call after the feasibility walk, based on the structural engineer's read. Geotech costs $4K-$12K and is non-refundable, so we only spend it when LADBS will require it.
How long is the LADBS process for a Hollywood Hills addition?
Single-story bump-out, no BHO trigger: 8-12 weeks. Master suite addition with BHO review: 14-20 weeks. Second-story with full structural retrofit and BHO + HCR-SUD: 18-24 weeks. Add Mulholland Corridor design review: 22-32 weeks. We track every plan-check correction and update you weekly.
Can I live in the house during the addition?
For a single-story rear bump-out, yes — we isolate the work area with temporary walls and keep the rest of the house operational. For a second-story addition, usually no — once we open the roof, the house is uninhabitable for 4-8 weeks. We help line up short-term housing and time the disruption window tightly.
Will the addition match the existing house architecturally?
Yes, unless you tell us otherwise. We do a full as-built measure of the existing house, document the existing materials and trim profiles, and either match exactly or design an intentional contrast. About 60% of our Hollywood Hills additions are matched-style (Mid-Century to Mid-Century, Spanish to Spanish). The other 40% are intentional contemporary additions to older houses — design call, your preference.
Free On-Site Home Addition Walkthrough in Hollywood Hills
Free feasibility walk. Netanel walks the lot, reads the existing structural envelope, pulls the BHO and Mulholland Corridor maps, and gives you a real range — usually $180K-$600K — and a real timeline before anyone signs a drawing contract. Text or call 818-605-1388, or use the form. CSLB #1105249. Architectural design since 2016. 200+ LA County builds. BBB A+. EPA RRP.
Book Free 48h Walkthrough →