105 Underhill Avenue: 21 likely condos rising from a Prospect Heights garage
Where Things Stand
I remember when this garage closed; the neighborhood scrambled for parking. I parked here for years, and it was the worst parking garage. It really wasn’t a garage; somehow, our car always came back covered in bird poop.
On to the real matter at hand. This building is a very interesting lot; how it connects with the space on St. Marks. I’m anticipating a unique configuration of units in terms of natural light.
The two buildings behind them, the parking garage at 105 Underhill Avenue and the smaller garage next door at 326 St. Marks Avenue, sold together in August 2024 for $11.65 million. This spring, the buyer closed on construction financing, and the building permits are in hand.
What the Paperwork Says
105 Underhill Avenue is a two-story parking garage built in 1930. About 23,000 square feet of building covering nearly all of a 13,450 square foot lot, zoned R6B. Building class G1, which is the city's code for a parking garage. No apartments today, which matters later.
The main job, filed in March 2025, describes a "vertical and horizontal enlargement and renovation of existing building," filed as a new building with existing elements to remain, with a brand-new certificate of occupancy. In plain English: parts of the garage stay, and a residential building gets built on and around them.
The numbers are the interesting part. Two stories becoming five. 25 feet tall becoming 55. Zero apartments becoming 21. Next door, 326 St. Marks Avenue goes from two stories to four and from zero apartments to three. That is 24 new homes on this corner.
The Elevator Question
The only new elevator filing so far, submitted September 11, is for the smaller building at 326 St. Marks Avenue, not the five-story building with 21 apartments. The old freight elevator in the garage was taken out last year. I am curious whether the two buildings will connect, or whether 326 St. Marks is being designed as a few larger, townhouse-style homes. The next round of filings should tell us.
Where It Stands Right Now
This one is well past the paperwork stage. The main job has had its permit since March, and excavation, foundation, structural, mechanical and plumbing permits have all been issued. A new sidewalk shed permit went through on September 10. The sprinkler system is approved but not yet permitted, which usually comes later in a build like this.
So: construction is underway, and the building has not gone to the Attorney General yet.
What the Ownership Structure Tells Us
The buyer is Underhill Heights LLC, based on Fulton Street in Clinton Hill. The owner and architect has constructed several other condo developments.
Here is what happened to his finished buildings. This is from the tax rolls, not from anybody's marketing.
529 Park Place, 8 units, now a condominium.
653 Bergen Street, 7 units, now a condominium.
546 Atlantic Avenue, 41 units, now a condominium.
178 Concord Street, 21 units, now a condominium.
261-265 1st Street in Park Slope, 9 units, now a condominium.
To be fair, not every project ended in individual condo sales. 186 21st Street is still a rental building, and 1007 Atlantic Avenue was set up as a condo and then sold as a whole building. For a project this size in Prospect Heights, though, the track record leans condo.
There is also a very close precedent on this block. 330-332 St. Marks Avenue, owned through the same Fulton Street address, turned 1930 one-story buildings into four-story homes that sold as condos in 2017.
What We Do Not Know Yet
No offering plan has been filed with the Attorney General, and no condominium declaration has been recorded. Until that happens, there is no unit mix, no pricing, and no official answer on condo versus rental. Because the garage was never residential, there are no tenants in the picture, which makes the path to a condo plan simpler than most conversions.
Sources: Everything above comes from public records: NYC Department of Buildings job filings and permits, ACRIS deed and mortgage records, PLUTO tax lot data, and the Department of Finance tax rolls.
Discover Other Similar Projects
If you are watching Prospect Heights, take a look at 196 Saint Marks Avenue and 139 Saint Marks Avenue, two boutique condos on the same avenue, and 447 Prospect Place, another building I am tracking from the permits before the offering plan.
Your next Brooklyn home may be closer than you think. Give me a call at 804-389-8451 if you want a heads-up when this one files.
Want to receive updates on 105 Underhill Ave? Sign up to follow below.