350 Butler Street

A sixty-six-by-hundred-foot lot, 6,600 square feet, and 41,772 gross square feet of building at a floor-area ratio of 6.33 — above what the lot alone would allow, which the recorded zoning-lot documents and the $1,540,000 development-rights easement of September 2020 account for. Development press at the permit stage reported eleven stories, thirty-one homes and a larger square footage; the as-built numbers are twelve stories and thirty-four homes, and the certificate of occupancy, the condominium subdivision, the unit lots and PLUTO all agree on them. Use the as-built figures.

The plan reads clearly from the unit numbers. Floors one through six carry four homes apiece — the A, B, C and D lines — which is a compact, efficient stack. Floors seven through ten carry two apiece, so the upper half of the building is made of larger homes. The top floor is two penthouses. The range runs studio to four-bedroom, which is a wide spread for thirty-four units and means the building's price-per-square-foot band will be correspondingly wide.

The façade is masonry, in the brick idiom that the Gowanus and Fourth Avenue rezonings both encourage and that this developer has used elsewhere in the borough. Interiors and staging were handled by the developer's own design practice — an in-house rather than commissioned program, which is characteristic of the firm and shows in the consistency of the finishes across the stack.

Thirty-four owners carry an attended lobby with doorman service, a fitness center, a children's playroom, two bicycle rooms, private storage and two roof decks. That is a high fixed-cost program for a small denominator, and it is the first thing to test in the budget. The envelope is designed to reduce heating and cooling demand; its actual effect on this building's budget has not been established here. A buyer should ask to see the actual energy line in the last two completed budgets rather than take the standard on faith, and should ask what the building's certification status is — designed to Passive House principles and certified Passive House are different claims, and the developer's own published language is the former.

Because no offering plan or audited financial statement for this building is on file with us, the ordinary capital questions are open rather than answered, and they should be put to the managing agent directly: the current budget and the energy line within it; the reserve balance and whether a reserve study has been done; any assessment since the 2024 closings; the ventilation and heat-recovery equipment's service history and maintenance contract, which is specialized machinery in a way a conventional boiler is not; and any warranty or construction-defect claims from a building that closed its first units only in 2024.

One operational note that is documented: the building received a final certificate of occupancy on May 1, 2024, after an initial temporary certificate in November 2023 and three renewals. A final certificate is the ordinary end state and yet it is not universal among the new condominiums in this part of Brooklyn — several of them are still operating on renewed temporary certificates. It is a small piece of evidence that this project was finished rather than merely occupied.

Three things are documented and they should not be run together.

The lot itself carries no environmental designation. There is no E-designation on this lot, and none anywhere on the block, in the Department of City Planning register. That is a straightforward negative finding, and it distinguishes this site from the Fourth Avenue corners to the south, where the 2003 rezoning imposed hazardous-materials designations tied to former underground gasoline tanks. We hold no Phase I or Phase II environmental report for this site, because we hold no offering plan for it — a plan would ordinarily disclose any such investigation, and a buyer who wants that record should request the plan and its environmental disclosure from the sponsor or the managing agent. Absence of an E-designation is not the same as an affirmative clean bill, and this page will not pretend otherwise.

The canal is a federal Superfund site and it is close. The Environmental Protection Agency added the Gowanus Canal to the National Priorities List on March 2, 2010. The head of the canal sits roughly three-tenths of a mile west of this address, down the same street. Dredging, capping and sewer-tank construction under that program have been an active condition in the neighborhood for years — barge traffic, staging, street work and the associated noise — and they will be for some time yet. On the other side of that work is a cleaned waterfront with public access, which is the long-term argument for being here at all.

The rezoning is the neighbor risk. The Special Gowanus Mixed Use District, adopted in November 2021, covers eighty-two blocks around the canal and entitles substantially more construction than has yet been built. This building sits inside it. Light, air and view lines from any given line in the stack should be underwritten against what the surrounding lots are permitted to build, not against what stands there now — and 350 Butler's own upper floors are the ones with the most to lose or keep.

Ownership form: Condominium, fee ownership. No ground lease or leasehold appears in the recorded documents.

Real estate taxes — no exemption on the roll. No 421-a, 485-x, J-51 or other exemption appears on any of the thirty-four unit lots in Department of Finance exemption detail for tax years 2021 through 2027, and the 2026/27 assessment roll carries zero exempt value on every lot. Abatements are applied on the bill, so check the apartment's tax bill. There is no phase-out schedule to model, but future bills still change with assessments and tax rates.

Everything else is undocumented and should be confirmed in writing. We hold no offering plan, by-laws, house rules or financial statements for this building. The right of first refusal, board approval process, pet policy, leasing and sublet rules, minimum lease term, pied-à-terre position, flip tax or transfer fee, and working capital contribution are therefore not established here and should not be assumed from the general practice of Brooklyn condominiums. Request the offering plan and the most recent audited statement from the managing agent at offer stage and read the policy stack from the documents themselves.

Recent sales

Recent closings at this building, from The Roebling Research Library. 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.

Market read. Most recent trades (2025) cleared a median $1,394/sf (floor-adjusted) across 4 sales. Floor-adjusted means each sale is restated to a constant mix of floors, so the figure can differ from the plain median of the sales listed above. Median listing discount 0.0% from the last ask.

Sales sourced from NYC Department of Finance recorded transfers (BBL 3-00943-7505; each condominium apartment is its own tax lot). Apartment-level facts (line, condition, asking-price context) curated and cross-verified in The Roebling Research Library. 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.

The roll shows no tax exemption. Check the apartment's tax bill for any abatement and underwrite that bill. Then, when you compare it to an abated building nearby, run the comparison over the life of the abatement rather than over a month.

Get the offering plan. It is the one document that settles the right of first refusal, the pet and sublet rules, the flip tax and the working capital contribution — and it is not on file with us. Nothing on this page should be read as establishing any of those.

Ask what "Passive House" means here precisely. The developer's published language is designed to Passive House principles. Ask whether the building was certified, by whom, and to what standard — and ask for the actual energy line in the last two budgets to see the benefit in dollars.

Ask about the ventilation equipment. Heat-recovery ventilation is specialized machinery with its own maintenance contract and its own eventual replacement cost, sitting in a building with thirty-four owners to fund it.

Thirty-four homes, a full amenity program, no commercial income. Read the budget, the reserve balance and any assessment history since the March 2024 closings.

The canal is three-tenths of a mile down your street, and the rezoning is all around you. Both are documented, both are neighborhood facts rather than defects, and both are worth understanding before rather than after.

Explain the envelope design. Airtightness, insulation and heat-recovery ventilation are part of the Passive House-principled design. Describe those features and provide operating data for any claim about energy savings or acoustic performance; photographs alone cannot establish either.

Reframe the tax position. A buyer coached to look for an abatement will read its absence as a negative. Present it as a bill with no phase-out step-up to model, and show the current bill; future bills still change with assessments and tax rates.

Lead with the final certificate of occupancy. In this pocket of Brooklyn that is a differentiator, and it takes one sentence.

Have the document package ready. Offering plan, current budget, most recent audited statement, reserve position. In a thirty-four-unit building with no plan in general circulation, supplying these documents helps the buyer and counsel begin their review.

If you're considering 350 Butler Street, also evaluate:

• 251 1st Street — terraced condominium three blocks south on Fourth Avenue; the abated, larger-staff alternative and the sharpest direct comparison
• Sackett Union (291 Union Street) — ground-up condominium on the Carroll Gardens–Gowanus seam at comparable scale
• Timber House (670 Union Street) — mass-timber Gowanus condominium; the other building in the neighborhood sold on its construction method
• 10 Nevins Street (The Brooklyn Grove) — larger ground-up condominium at the Boerum Hill edge; the full-amenity, bigger-denominator alternative
• 480 Degraw Street — Gowanus-edge condominium with a documented site-contamination history and no board approval; useful as a contrast on environmental disclosure
• 561 Pacific Street — design-led condominium a short distance north; the architecture-first alternative
• 243 4th Avenue (Parlour) — Fourth Avenue condominium; the avenue-frontage comparison
• 228 13th Street — 2025 condominium at the Green-Wood end of the Slope with deeded parking; the other unabated new building in this cluster
• 229 9th Street (Luna) — ground-up condominium on the far side of the canal
• 345 Carroll Street — boutique Carroll Gardens condominium; the low-rise alternative