Office-to-Residential Conversion Economics in NYC

The conversion underwriting stack

A complete NYC conversion underwriting works through the following stack, in order:

• Acquisition basis — purchase price per gross SF of the office building, plus closing costs and basis-loaded soft costs.
• Hard construction cost — total demolition, structural, façade, mechanical, plumbing, electrical, and unit fit-out cost, expressed both per gross SF and per residential door.
• Soft costs — architect, engineering, legal, financing, insurance, marketing, lease-up reserves; typically 15–25% of hard.
• Construction-period carry — interest, real estate tax during construction (partially offset by 467-m if it accrues during construction), and insurance.
• 467-m abatement value — NPV of the 35-year property-tax benefit, discounted to construction completion.
• Stabilized rent roll — market-rate and affordable rent per unit, building amenity revenue, parking and ancillary income, vacancy and collection loss.
• Stabilized operating expenses — taxes (post-abatement), insurance, utilities, payroll, repairs and maintenance, management fee, replacement reserves.
• Exit value — stabilized NOI capitalized at market exit cap, or refinance proceeds plus residual building value.

Acquisition basis — what conversion buildings actually trade for

Conversion-candidate office buildings trade at meaningful discounts to occupied stabilized office of similar vintage, reflecting their reduced office cashflow, the conversion capex burden, and the limited buyer universe. Skyline-brokered comps span a wide range:

• 6 East 43rd Street — $135M acquisition for a pre-war Midtown building suited for 441-unit residential conversion (Vanbarton Group), implying a basis well below same-vintage occupied office in the submarket.
• 101 Greenwich Street — $105M acquisition by Metro Loft for FiDi conversion candidate, reflecting Special Lower Manhattan Mixed Use District eligibility and Metro Loft's deep conversion track record.
• 530 West 25th Street — $72M Chelsea acquisition reflecting strong residential submarket demand and conversion-vs.-renovation optionality.

Hard cost per door — the central economic variable

Hard construction cost is the single largest controllable economic variable in conversion underwriting. The 2025-era NYC conversion benchmark Skyline applies is:

• $300K per door — strong existing conditions, minimal façade work, centralized plumbing, modest scope of mechanical replacement, market-rate finishes.
• $400–500K per door — typical mid-quality Manhattan conversion with façade upgrades, new wet-stacks, distributed residential mechanical, and competitive market-rate finishes.
• $600K+ per door — premium conversions with extensive façade restoration, landmark complications, condo-quality finishes, or unusual structural interventions.

Soft costs and construction-period carry

Soft costs on a typical NYC conversion run 15–25% of hard, comprising architect and engineering, legal (including 467-m and HPD affordable-marketing counsel), financing fees, insurance, marketing and lease-up reserves, and developer fee. Buyers who underwrite soft costs at 10% routinely miss budget; sophisticated conversion developers (Vanbarton, Metro Loft, Silverstein) consistently underwrite at the higher end of the band.

Construction-period carry is dominated by interest on the construction loan. The Brookfield $300M construction loan supporting 6 East 43rd Street is illustrative — at construction-loan rates on the order of SOFR + 350–450 bps and a 30–36 month construction period, interest carry alone consumes a meaningful slice of total project cost. Real estate tax during construction is partially offset by 467-m if the abatement accrues during the construction period, but the timing of accrual versus stabilization needs disciplined modeling.

Lease-up timing is the other concealed risk. Market-rate units lease conventionally over 6–12 months; affordable units run through HPD Housing Connect and typically add 6–12 months for lottery, eligibility verification, and tenant move-in. Total lease-up to stabilized occupancy is usually 12–18 months from construction completion, and the carry during this window is meaningful.

467-m abatement NPV — the largest non-cost line item

The 467-m abatement is typically the single largest economic line item in conversion underwriting after acquisition basis itself. Skyline models 467-m value using the building's as-of-right tax bill (post-conversion), the statutory abatement schedule, and a discount rate matched to the developer's cost of capital (typically 7–9%).

On a stabilized building with $200/SF of residential value and a meaningful pre-abatement tax bill, the 35-year NPV typically lands in the 15–25% of stabilized value range. On 6 East 43rd Street's 441-unit, $135M-acquired conversion, the 467-m benefit is a material component of total deal economics — buyers without 467-m competence would not have been able to underwrite to a winning bid.

Care is required around when 467-m benefit accrues (construction-period vs. post-completion), how the affordable-unit obligation flows through stabilized cashflow, and how exit buyers will underwrite the residual abatement value. These are not back-of-envelope calculations and require dedicated tax counsel.

Stabilized rents — what converted Manhattan product actually achieves

Converted Manhattan rental product in 2025 stabilizes at meaningfully higher rents than older free-market multifamily of similar location, reflecting new finishes, modern systems, and amenity-rich common space. Skyline's current rent benchmark band for converted Manhattan rental is:

• Studio — $3,800–$5,200/month depending on submarket
• One-bedroom — $4,500–$6,500/month
• Two-bedroom — $6,500–$9,500/month
• Three-bedroom and larger — $9,500–$15,000+/month

Exit cap rates and stabilized residential value

Stabilized Manhattan multifamily exit cap rates in 2025 are running 4.5–5.5% for free-market product and somewhat higher for buildings with meaningful regulated (affordable) cashflow. Conversion underwriting must reconcile the entry basis, total project cost, and exit cap to a defensible stabilized valuation and a residual developer margin of 15–25% over total cost.

Refinance assumptions are common — many conversion developers underwrite a hold-and-refinance scenario rather than a sale, taking advantage of permanent debt liquidity (agency, life-company, CMBS) at stabilized loan-to-value. The refinance proceeds plus residual building value typically produce equity multiples in the 1.7–2.5x range and IRRs in the high-teens to mid-twenties for well-executed deals.

Buyers in the stabilized exit market for 467-m product are increasingly experienced underwriting the abatement runoff and the regulated cashflow — this market did not exist five years ago and has matured rapidly. Skyline's investment-sales practice intersects this exit market directly via the manhattan-investment-sales-broker mandate set.

Pulling it together — sample conversion economics

A representative Skyline-screened Manhattan conversion candidate might run roughly as follows (illustrative; every deal is fact-specific): 200,000 GSF pre-war Midtown building, acquired at $135M ($675/SF acquisition basis). Conversion to 250 residential units at average $450K hard cost per door ($112.5M total hard cost), plus 20% soft cost ($22.5M), plus $25M construction-period carry — total project cost approximately $295M.

Stabilized residential building of 250 units with blended market and affordable rents producing ~$25M NOI post-abatement adjustments, valued at $500M at a 5% cap. Plus 467-m abatement NPV of ~$60–80M flowing through cashflow over 35 years. Developer profit margin of $200M+ over total cost — equity multiple typically 2.0–2.5x and levered IRR in the high teens depending on capital structure.

These numbers are illustrative — every conversion deal turns on its specific physical and zoning facts — but the structure is representative of Skyline-brokered deal economics on transactions like 6 East 43rd Street, 101 Greenwich Street, and 530 West 25th Street. Buyers and equity partners should be able to defend each line item against Skyline's benchmark band; deals that drift outside the band typically do not close.

How Skyline supports conversion underwriting

Skyline Properties is not a generalist office brokerage running occasional conversion deals — conversion brokerage is a structural part of the practice, with mandates priced and marketed against the full economic framework above. Robert Khodadadian personally walks each conversion-mandate building with conversion architects, 467-m counsel, and the relevant conversion-finance bench (Brookfield, MF1, JP Morgan, and other conversion-active lenders) to validate the underwriting envelope before bringing the asset to market.

Buyers — Vanbarton, Metro Loft, Silverstein, GFP, Stellar, RXR, and the broader conversion universe — engage Skyline mandates with confidence because the underwriting is consistent with how they themselves model conversions. Sellers benefit from accurate pricing, fast execution, and avoidance of the broken-process risk that defines conversion sales run by non-specialist brokers. The 6 East 43rd Street, 101 Greenwich Street, and 530 West 25th Street transactions are case studies of this approach in practice.