15-19 Broad St

Where 15-19 Broad St is

Its block in Downtown Boston, drawn from Boston's own building outlines and street centerlines.

The plan: window line, shape and floor rhythm

36 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.

The typical floor has 1,174 ft of exterior wall, and across 32 residential floors the building carries 25,081 ft of it in total, divided among the 706 homes this screen estimates.

Its plate is moderately compact at 0.57: a squarish plan, with enough perimeter for a conventional double-loaded corridor. How window line and plate shape are measured.

At the model’s 750 sq ft average, the plan works out at about 22.1 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 15-19 Broad St scores 35 out of 100

The weighted components add to 53, but the score is capped at 35 because its deepest interior point is 100 ft from a facade, past the 80 ft threshold beyond which conversion requires carving a light well.

Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 0 out of 100: deepest interior point 100 ft from a facade, scored from 80 ft down to 40 ft.

Built in 1920

Boston records this building as going up in 1920, which puts it in the interwar stock.

As a rule, steel or concrete frames with punched windows and plates still narrow enough for daylight to reach the middle, often with high ceilings. Among the most convertible stock there is, and the reason so many early conversions were of buildings this age. That is the era’s general tendency rather than a finding about this building — the model reads an outline and a height, and can see nothing inside — but it is the first thing an architect would want to know, and it colours how much confidence the 68% daylight figure above deserves.

What the conversion would cost

$360 per square foot all-in across 971,397 sq ft of converted floor, or $349.7M in total — about $495K for each of the 706 homes.

That cost is charged across every converted square foot, including the 308,598 sq ft of windowless core, which has to be gutted, re-plumbed and sprinklered like the rest of the building and then earns nothing. Against it the model sets a completed value of $442K a home, which for 706 homes is $311.7M.

What would have to be true

A $38.0M gap before any grant, $28.0M after the modeled one. The smallest single change that would close it: average unit size 8% down.

The shortfall before any grant is $38.0M. Closing it from the value side means each of the 706 homes finishing at $495K rather than the $442K the model assumes — 12% more. Closing it from the cost side means getting all-in cost down from $360 to $321 per square foot.

A modeled RESIDE grant of $10.0M moves that threshold to $481K a home. That is still above the $442K assumed, leaving $28.0M uncovered, which is why the grant does not unlock this one.

Nor do all four levers have to move. For 15-19 Broad St, one alone would close the gap at:

All four are sliders in the survey, where 15-19 Broad St re-scores against your own numbers.

How it compares in Downtown Boston

15-19 Broad St ranks 90th of the 96 buildings screened here, against a median score of 89.

Its floor plate is better lit than 13% of them, and shallower than 4% of them at its deepest interior point. On size it is the 15th largest by estimated homes. The full survey of all 96 buildings ranks and maps every one of them, and the list by address links each to its own page.

Within the SKY zone

47th of 52 zoned SKY — the comparison that shares its rules, rents and streets.

52 of the screened buildings are zoned SKY. 15-19 Broad St ranks 47th of them against a median score of 88. 40 score 70 or more, their median deepest interior point is 51 ft from a facade against this building’s 100 ft, and together they would hold an estimated 19,019 homes. The group’s top scorer is 147 Milk St, at 100.

Its nearest match in size: 185 Franklin St

The screened building closest to 15-19 Broad St in converted floor area is 185 Franklin St: 1,007,277 sq ft over 29 stories, against 971,397 sq ft over 33 here.

The two land within a few points of each other — 35 here, 35 there — so at this size the screen reads them as much the same prospect. On the money they sit in the same place: each falls short even with the modeled grant. The two stand about 1,200 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 15-19 Broad St $10.0M, on the assumption it qualifies. Whether it does, no published dataset can say.

That figure assumes the building meets the Act’s vacant-and-abandoned test, which turns on code-enforcement and receivership records no city publishes.

It does not sit in a 2018 designated Opportunity Zone, so it would not draw that Section 201 priority.

Other buildings screened near 15-19 Broad St

The 4 closest the screen also covers, from 270 ft away. They are the colored outlines on the plan at the top of this page.

• 43-65 State St
  45 stories · 67% daylit · 940 estimated homes · scores 61/100 (Worth a feasibility study)
  about 270 ft away
• 74-84 State St
  10 stories · 98% daylit · 116 estimated homes · scores 97/100 (Strong candidate)
  about 290 ft away
• 1 Liberty Sq
  13 stories · 84% daylit · 156 estimated homes · scores 87/100 (Strong candidate)
  about 360 ft away
• 36-44 Broad St
  10 stories · 96% daylit · 248 estimated homes · scores 100/100 (Strong candidate)
  about 360 ft away