33 Arch St

Where 33 Arch 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

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

The typical floor has 649 ft of exterior wall, and across 33 residential floors the building carries 21,401 ft of it in total, divided among the 620 homes this screen estimates.

Its plate is compact at 0.73: close to a square or a circle, the most efficient envelope an office can have and the least generous one for apartments: little perimeter to divide among homes. How window line and plate shape are measured.

At the model’s 750 sq ft average, the plan works out at about 18.8 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 33 Arch St scores 71 out of 100

Daylight efficiency 65, Interior depth 51, Scale 100, Finance 97 — each out of 100, then weighted.

Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 51 out of 100: deepest interior point 60 ft from a facade, scored from 80 ft down to 40 ft.

Built in 2002

Boston records this building as going up in 2002, which puts it in the modern stock.

As a rule, newer systems and better structure, but usually built deep and sealed for office use, and rarely cheap enough to buy at a price that lets a conversion pencil. 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 72% daylight figure above deserves.

What the conversion would cost

$360 per square foot all-in across 804,002 sq ft of converted floor, or $289.4M in total — about $467K for each of the 620 homes.

That cost is charged across every converted square foot, including the 221,843 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 620 homes is $273.7M.

What would have to be true

A $15.7M gap before any grant, $5.7M after the modeled one. The smallest single change that would close it: average unit size 2% down.

The shortfall before any grant is $15.7M. Closing it from the value side means each of the 620 homes finishing at $467K rather than the $442K the model assumes — 6% more. Closing it from the cost side means getting all-in cost down from $360 to $340 per square foot.

A modeled RESIDE grant of $10.0M moves that threshold to $451K a home. That is still above the $442K assumed, leaving $5.7M uncovered, which is why the grant does not unlock this one.

Nor do all four levers have to move. For 33 Arch St, one alone would close the gap at:

All four are sliders in the survey, where 33 Arch St re-scores against your own numbers.

How it compares in Downtown Boston

33 Arch St ranks 74th of the 96 buildings screened here, against a median score of 89.

Its floor plate is better lit than 16% of them, and shallower than 30% of them at its deepest interior point. On size it is the 19th 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

39th of 52 zoned SKY — the comparison that shares its rules, rents and streets.

52 of the screened buildings are zoned SKY. 33 Arch St ranks 39th 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 60 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: 99 High St

The screened building closest to 33 Arch St in converted floor area is 99 High St: 797,122 sq ft over 34 stories, against 804,002 sq ft over 34 here.

33 Arch St scores 71 to its 61, and with the size held roughly equal most of that lead comes from interior depth: 51 out of 100 here, 21 there (deepest interior point 72 ft from a facade, scored from 80 ft down to 40 ft). 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 33 Arch 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 33 Arch St

The 4 closest the screen also covers, from 140 ft away. They are the colored outlines on the plan at the top of this page.

• 40-62 Franklin St
  5 stories · 85% daylit · 47 estimated homes · scores 76/100 (Strong candidate)
  about 140 ft away
• 64-74 Franklin St
  10 stories · 91% daylit · 94 estimated homes · scores 90/100 (Strong candidate)
  about 150 ft away
• 181-185 Devonshire St
  10 stories · 100% daylit · 68 estimated homes · scores 92/100 (Strong candidate)
  about 200 ft away
• 157-175 Devonshire St
  11 stories · 97% daylit · 162 estimated homes · scores 100/100 (Strong candidate)
  about 200 ft away