Sackett Union (291 Union Street)

Seven stories, seventy feet, construction classification 1-C, R-2 occupancy, on a 24,086-square-foot lot in an R6A district. The tax roll records about 73,100 square feet of building area — roughly 60,800 residential and 12,300 commercial — across 46 tax lots, of which 32 are residential apartments. The residential lines run three maisonettes, then lettered apartments on the upper floors, then three penthouses, with the certificate of occupancy describing a mix of full and half units floor by floor as the split-level sections stack.

The commercial component is substantial and should be understood rather than skipped. The certificate of occupancy records ground-floor offices to the north and south and a community-facility ambulatory diagnostic or treatment health care facility, which is why the Department of Finance classifies the property as a mixed residential and commercial condominium. Non-residential units in a condominium carry their own common interests and pay their own charges; ask the managing agent what proportion of the budget they carry, who occupies them, and whether the commercial units are current.

Amenities are modest and legible: a residents' recreation room, rooftop recreation, cellar laundry, trash, bicycle and storage rooms. The garage is the notable one. Forty accessory spaces sit in the cellar — thirty-six single and four tandem, with the tandem spaces restricted so that they can only be held by the owner of the space in front of them. Twenty-five spaces were assigned to particular apartments and folded into those apartments' purchase prices, which means parking here is an attribute of specific units rather than a market you can enter later. The other eleven were carved into separate tax lots and deeded to the townhouse owners. If parking matters to you, confirm on the unit itself, in writing, before contract.

Because the property is outside the Carroll Gardens Historic District, exterior work here proceeds through the Department of Buildings alone. The district covers Carroll and President Streets between Smith and Hoyt and nothing further; this block is two streets north of it.

A thirteen-year-old building with a garage, a rooftop amenity and a commercial component is a real operating business, and the diligence list reflects that. The condominium's Department of Housing Preservation and Development registration names Choice NY Management as managing agent for the current cycle.

Ask for three years of financial statements, the current budget, the reserve balance, and the minutes covering any assessment. On a 2013 building the envelope should still be in its first maintenance cycle, but the items to check are specific: the roof and the rooftop recreation deck, the garage slab and its waterproofing, the elevator, the sprinkler and fire-alarm systems, and any water history at the setback glazing on the top two floors. Buildings of this vintage and detailing occasionally carry sponsor-era construction claims; ask whether any were pursued and how they resolved.

The garage deserves its own question. Structural repairs to the parking spaces are charged, under the plan, to the unit owners and townhouse owners whose units include a space rather than to the condominium at large — an allocation that is unusual enough to be worth confirming in the by-laws as they currently read.

Finally, the taxes. The plan priced units against 421-a benefits commencing with the 2014/15 tax year. Where that benefit sits today, and what the unit's tax bill will look like as it steps, is the single most consequential number in the carrying-cost analysis and the one most often misstated. Pull the current bill.

Recent sales

Sales sourced from NYC Department of Finance recorded transfers (BBL 3-00339-7503) 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.

Confirm the parking in writing. Twenty-five spaces are attributes of specific apartments; four are tandem with a restriction attached; eleven belong to the townhouses. This is not a waiting list you can join.

Pull the current tax bill and model the 421-a step. The plan priced units both with and without the benefit and dated its start to the 2014/15 tax year. The step matters more to your monthly than the common charge does.

Tour the section, not the floor plan. Split-level, interlocking apartments with the primary bedroom on an upper level are a specific product. See the actual unit.

Ask what the commercial and community-facility units contribute. Roughly 12,300 square feet of commercial area sits on the tax roll. Occupancy, common-interest share and payment status are all fair questions.

Read the garage-repair allocation. Structural repairs to the parking spaces are charged, under the plan, to the owners whose units include one. Confirm how the by-laws read today.

Lead with what the neighborhood does not have. New-construction condominium apartments with an elevator, parking and rooftop space are rare in Carroll Gardens, and that is the listing's first sentence.

Name the architect accurately. Rogers Marvel Architects, now Rogers Partners, designed the development; the practice's own project record covers it. That is a documented credential and worth stating.

Present the tax line honestly alongside the common charge. Buyers who see only the common charge will misprice the monthly, and they will find out at the mortgage application.

Sell the section. Split-level layouts with the bedroom above photograph badly and show well. Get buyers into the apartment.

Assemble the condominium package before the first offer. Financials, current budget, reserve balance, house rules, rental policy, the waiver procedure, the parking documentation for the specific unit, and the alteration approvals for any work done.

If you're considering Sackett Union, also evaluate:

• 145 President Street — the neighborhood's other boutique new-construction condominium with parking; the closest direct peer
• 345 Carroll Street — 32-unit condominium at the eastern edge of the neighborhood, with parking and storage sold separately
• 344 Degraw Street — the turn-of-the-millennium condominium a few blocks north; the earlier generation of the same product
• 505 Court Street (Court Street Lofts) — the neighborhood's loft alternative further south on Court
• 358 Court Street — the South Congregational Church complex; Carroll Gardens' church conversion in condominium form
• 450 Clinton Street — the Old Westminster Church cooperative on the First Place garden block; the co-op comparison
• 500 4th Avenue — the larger new-development condominium alternative on the neighborhood's eastern edge
• 401 Hicks Street (The Arches at Cobble Hill) — Cobble Hill condominium with parking; the cross-neighborhood comparison
• 11 Hoyt Street — the Downtown Brooklyn amenity condominium, for buyers weighing services against neighborhood