170 East 77th Street (Diamond House)
170 East 77th Street, New York, NY 10075
Lenox Hill, Upper East Side
BBL 1014117502 · BIN 1043179
- Year built
- 1940
- Type
- Condominium
- Units
- 53
- Floors
- 11
- Landmark
- No
Every recorded sale at this building, 2007–2026
Price-per-square-foot over time, the line- and floor-premium curves, and every recorded sale.
- Median $/sf
- $1,380
- Listing discount
- 2.6%
- Recorded sales
- 87
- On record
- 2007–2026
Diamond House is a conversion, and almost everything a buyer needs to understand about it follows from that. The building went up around 1940 as a rental apartment house on a quiet mid-block stretch between Lexington and Third, half a block from Lenox Hill Hospital. It traded in 2004 and was renovated and offered as a condominium under a plan dated December 1, 2006, with the declaration recorded in August 2007 and the first individual unit deeds recorded that same year. Twenty-one apartments closed in 2007; the rest have closed steadily over the two decades since.
That means the building is not a sellout. It is a non-eviction-style conversion in which the sponsor sold apartments as they came available and continued to rent the rest. The pattern is visible in the record. Of the 53 residential unit lots on the current tax roll, 43 carry at least one recorded deed; ten have never been individually deeded. The audited financial statements for 2019 record that the sponsor's common charges represented roughly 21 percent of the condominium's total common charges that year, and the most recent offering-plan amendment on file lists thirteen apartments and fourteen storage units still held as unsold and offered at stated prices. This is a working, for-sale condominium with genuinely dispersed ownership — the current tax roll shows roughly 45 distinct owners across the residential lots, with no bulk holder and no unit lot carried in the Department of Finance's rental class — but a prospective buyer should know that a meaningful minority of the apartments are still sponsor-owned and tenanted.
The second thing to understand is that the sponsor has not controlled the building for a long time. The offering-plan amendments record that as of October 14, 2009 the sponsor no longer controlled the board of managers, and the board has since had a non-sponsor majority with a single sponsor representative. Governance decisions at Diamond House are made by resident owners.
The third is the physical product. The 2007 renovation was a real one rather than a cosmetic pass. It produced a skylit lobby with curved glass walls behind a metal-and-glass marquee, a fitness center, and a landscaped roof deck, and it delivered apartments with sunken living rooms, beamed ceilings, curved partition walls at the kitchens, and in many cases in-unit laundry. What survived is the prewar bone structure: bay windows in the chamfered wings, generous room proportions, and floor plans in the 895-to-2,500-square-foot range that give the building four-bedroom inventory a postwar building of the same footprint could not offer.
Architecture and unit composition
The building occupies a 12,770-square-foot mid-block lot with a 125-foot frontage on East 77th Street, in an R8B zoning district — a contextual district whose 4.0 residential floor area ratio is well below the building's existing 7.26. The building is substantially overbuilt for its current zoning, which is common for prewar stock on the Upper East Side and means no meaningful expansion is available on the site.
The elevation is pale yellow brick with a recessed central entrance approached by a short step-down. The two flanking wings carry chamfered corners with bay windows, which is what gives the apartments behind them their light. The conversion's most visible exterior gesture is the entrance marquee; its most consequential interior one is the lobby, rebuilt with a skylight and curved glass.
Apartment inventory runs from one-bedroom residences of roughly 900 square feet through four-bedroom homes approaching 2,500. Layouts are prewar in character — enclosed kitchens, defined dining areas, gallery entries in the larger lines — modified by the conversion, which introduced sunken living rooms and the curved floor-to-ceiling partitions that define the kitchens in many units. A number of lower-floor residences carry terraces. Storage rooms were sold as separate condominium units and trade independently; twenty-seven of them exist as their own tax lots, and a buyer who wants storage should establish early whether one is available for purchase rather than assuming building-wide storage is included.
The ground floor holds professional and commercial units — originally two professional units, later subdivided into four — which are separately owned and used for medical and professional offices. That is a natural use given the proximity to Lenox Hill Hospital, and it means daytime foot traffic through the lobby is higher than at a purely residential building of this size.
Building operations
Diamond House runs with full-time doorman and concierge coverage and a resident superintendent. Building staff are covered by a collective bargaining agreement with SEIU Local 32BJ, and the condominium participates in the union's multi-employer pension and health plans; payroll and related expenses are the dominant line in the operating budget, running well over half of total expenses in the years for which audited statements are on file.
Three items in the capital record are worth a buyer's attention.
The condominium carries a mortgage. In September 2015 the condominium refinanced the loan on the superintendent's apartment, Unit 3A, which it owns, with a $1,050,000 mortgage from a cooperative-sector lender. The loan carried a ten-year term with a rate reset in 2020 and a stated maturity date of October 1, 2025. That date has now passed. Whether the loan was repaid, extended or refinanced — and on what terms — is a live diligence question and is not answerable from the documents on file.
Local Law 11 façade work has been done, recently. The condominium completed a façade restoration in 2019 at a cost of approximately $345,189 including change orders, with Spivak Architects overseeing the project. That is a completed cycle rather than a pending one, which is a meaningful positive for a building of this age.
Reserves are thin and the capital contribution is standing. The reserve fund stood at roughly $302,000 at the most recent year-end in the audited statements on file, down from about $591,000 a year earlier after the façade work. Against that, the board has run a standing monthly assessment equal to 10 percent of common charges since July 1, 2013 — imposed both to rebuild the reserve and to satisfy FHA lending requirements — which contributed roughly $120,000 a year in the years reported. A buyer should read that assessment as a permanent component of the monthly cost rather than a temporary levy, and should confirm the current reserve balance directly.
The building also experienced a fire in September 2019 that damaged several apartments; the condominium received an insurance recovery and the matter appears in the audited statements as resolved. Separately, tax certiorari proceedings produced real estate tax refunds to unit owners in 2017 and 2018 and a further reduction for the 2019/20 tax year.
Policy framework
Ownership form: Condominium. Purchases close through the board's right of first refusal rather than a cooperative-style approval. Management-sourced records indicate the board reviews a package within 14 days of receipt and returns the signed waiver within a further 7 days, and does not accommodate rush requests — plan a closing timeline accordingly.
Subletting: Permitted, with a firm floor: no lease or renewal for a term of less than 12 months will be considered by the board of managers. Short-term rental is not available here.
Capital contribution: 10 percent of common charges, payable by the purchaser at package submission. This is separate from the working capital contribution of one month's common charges due at closing, and separate again from the standing monthly 10 percent assessment.
Pied-à-terre, LLC, trust and foreign ownership: Permitted under the standard condominium framework. Buyers intending to take title in a trust should confirm the effect on co-op and condo property tax abatement eligibility before closing; management-sourced records flag this specifically.
Alterations: A refundable alteration security deposit is required, scaled by project type per management-sourced records. Confirm the current alteration agreement and deposit schedule with the managing agent.
Real estate taxes: No building-wide abatement. Underwrite full taxes on the specific unit.
Local Law 97
- 2024–2029 annual penalty
- $0 (under cap)
- 2030–2034 annual penalty
- $51,902/yr
- Per unit / month range
- $0 – $82
Source: NYC LL84 benchmarking and PLUTO · The Roebling Research Library. City record last verified September 2026.
See full Local Law 97 analysis — emissions history, scenarios, methodology →Facade safety — Local Law 11
The latest available filing classified the facade as SWARMP — Safe With A Repair and Maintenance Program: the engineer identified conditions requiring monitoring or repair before the next inspection cycle. The scope, timeline, and how the building funds the work are building-specific — we review the filings and board materials for you.
How to read this, and where it comes from
QEWI = Qualified Exterior Wall Inspector — the licensed engineer the city requires to sign the report (the independent expert, not the managing agent).
Penalties shown are amounts DOB assessed against filings on record across 2005–10 to 2020–25. The FISP dataset does not record whether they were paid, contested or remain open, so treat the figure as history rather than a current balance and confirm the building’s standing with the managing agent.
Source: NYC DOB facade filings (FISP) · The Roebling Research Library. City record last verified September 2026.
Recent sales
Individual unit deeds at Diamond House begin in 2007 and have been recorded in almost every year since, with 111 deeds across the residential lots through 2026. That is enough depth to build same-building comparables at most sizes, though not at every line — several apartments have traded only once since the conversion, and ten have never traded at all.
Pricing behaves like what the building is: a well-renovated prewar conversion on a quiet mid-block Lenox Hill street, without a garage, without a full amenity program, and without a marquee address. On a dollars-per-square-foot basis it sits below the Park and Fifth Avenue condominium tier and in line with the mid-block Lexington-to-Third condominium inventory of the East 70s. The larger three- and four-bedroom residences are the building's scarcest and strongest product, because floor plans of that size in a full-service prewar building on this corridor are genuinely limited in supply.
Two structural items should be priced into any analysis. The first is the standing 10 percent capital assessment, which raises the effective monthly cost above the headline common-charge figure. The second is the sponsor's remaining unsold inventory: a building in which a single owner still controls a meaningful minority of the apartments and rents them can face lender scrutiny on owner-occupancy ratios, and a buyer financing a purchase should confirm the current owner-occupancy percentage early rather than at commitment. Unit-level transaction history is maintained in The Roebling Research Library and shared with clients during diligence.
Recent closings at this building, curated by The Roebling Team research desk. Prices are the transfer amounts recorded with the NYC Department of Finance; apartment-level detail is checked against the building’s own file in The Roebling Research Library before publishing.
| Date | Unit | Apartment | Price | PPSF | vs. Ask |
|---|---|---|---|---|---|
| May 28, 2026 | 6D | 2 BR · 2 BA · 1,357 sf | $1,950,000 | $1,437/sf | -2.3% |
| Dec 29, 2025 | 2D | 2 BR · 2.5 BA · 1,357 sf | $1,700,000 | $1,253/sf | -2.9% |
| Aug 20, 2025 | 6G | 2 BR · 2 BA · 1,282 sf | $1,680,000 | $1,310/sf | -1.2% |
| Sep 29, 2023 | 9C | 4 BR · 4 BA · 2,500 sf | $3,350,000 | $1,340/sf | -6.9% |
| Sep 22, 2023 | 6D | 2 BR · 2 BA · 1,357 sf | $1,900,000 | $1,400/sf | +0.3% |
| Jun 10, 2022 | 10E | 1 BR · 1 BA · 895 sf | $1,125,000 | $1,257/sf | -0.4% |
| May 26, 2022 | 7C | 2 BR · 2 BA · 1,200 sf | $1,600,000 | $1,333/sf | +0.0% |
| May 11, 2022 | 2 | 4 BR · 4.5 BA · 3,531 sf | $4,999,999 | $1,416/sf | -4.8% |
Market read. Most recent trades (2026) cleared a median $1,380/sf across 1 sale. Median listing discount 2.6% from the last ask — a recurring negotiation gap worth pricing into any offer or listing strategy.
The retrade record
Lines that have traded more than once in the public record — the building’s appreciation arc, apartment by apartment.
Full closing history with price-per-square-foot over time, the complete retrade record, and every line that has traded.
Sales sourced from NYC Department of Finance recorded transfers (BBL 1-01411-7502) and verified listing data. Apartment-level facts (line, condition, asking-price context) curated and cross-verified by The Roebling Team research desk. Not all transactions cross-verify with ACRIS records — sponsor and LLC purchases sometimes record at stipulated values rather than market price; square footage from recorded condo declarations and offering plans.
What to know if you’re buying
Ask about the 2025 mortgage maturity. The condominium's loan on the superintendent's unit was scheduled to mature October 1, 2025. Establish what happened to it.
Read the assessment as permanent. The 10 percent monthly capital assessment has run since 2013. Add it to common charges when you compute carrying cost, and add unabated taxes on top.
Confirm the owner-occupancy ratio. Sponsor-held rental apartments remain in the building. This matters to lenders, and it can matter to the availability of FHA-eligible financing.
Do not assume PLUTO's unit count. City data reports 85 units at this address. There are 53 apartments; the rest are storage rooms and professional offices. Any automated valuation built on the PLUTO figure will be wrong.
Buy the storage separately or not at all. Storage rooms here are individually deeded condominium units. If you need one, negotiate for it as part of the transaction.
Check the tax certiorari and assessment history. The building has actively contested its assessment and produced refunds. Ask where the current cycle stands.
What to know if you’re selling
Lead with the floor plan. The larger residences here — three- and four-bedroom layouts with sunken living rooms and real dining space — are the scarcest product in the building and among the scarcer products on the corridor at this price tier.
Be direct about the assessment. It is not a defect, and it has a documented purpose: rebuilding reserves and maintaining FHA eligibility. Presenting it that way, with the completed 2019 façade restoration alongside it, is far stronger than letting a buyer discover it in the financials.
Position against mid-block condominiums, not against Park Avenue. The right comparable set is the Lexington-to-Third condominium inventory in the East 70s.
Expect a deliberate board timeline. A 14-day review plus a 7-day waiver return is the stated process, and rush requests are not accommodated. Build it into the closing schedule at contract.
Comparable buildings
If you're considering Diamond House, also evaluate:
- 145 East 76th Street — the other condominium on the same tax block; the closest structural comparison available
- 175–177 East 77th Street — condominium on the same street, one block west toward Lexington
- 201 East 77th Street — the corner alternative on the same street at Third Avenue
- The Siena (188 East 76th Street) — full-service condominium one block south; a larger, amenity-heavier alternative
- The Morgan Studios (170 East 78th Street) — the same mid-block position one street north, at a very different scale
- 150 East 78th Street — mid-block prewar alternative one street north
- 200 East 78th Street — corner full-service alternative on the same corridor
- 151 East 76th Street — prewar cooperative two streets south; the co-op comparison, with entirely different policy and financing rules
The neighborhood
For the full corridor — architecture, schools, transit, and pricing across Upper East Side — read The Roebling Team Guide to Upper East Side.
How to read the facts on this page. Items attributed to an offering plan describe the building as it was offered at that filing — unit mix, square footage, the amenity program as planned. They are not a statement about how the building operates today. Tax and compliance figures are sourced separately to current City records and carry their own dates. House rules, staffing and fee policy can change by board resolution without any public filing: treat every policy line here as a starting point for diligence and confirm it with the managing agent.
Considering a move at Diamond House?
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