64-74 Franklin St

64-74 Franklin St is a 10-story building in Downtown Boston with 91% of its floor area within daylight reach of a facade. This screen estimates 94 homes and scores it 90 out of 100 for office-to-residential conversion suitability.

MA-7 & MA-8 · Screened 2026-10-04 · Strong candidate

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Where 64-74 Franklin St is

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

Suitability score

0–29

30–49

50–69

70–100

Already housing
Not screened
64-74 Franklin St

64-74 Franklin St and the 1,000 ft of Downtown Boston around it. The streets are drawn at the width of the right-of-way they run down, sidewalks included, and named, and every building on these blocks is drawn. What is left open and stippled is neither: a surface lot, a plaza or a vacant parcel. The screened buildings are colored by the ramp above, the same one the district map uses, carry their score, and each is a link to its own page. Each casts a shadow as long as its measured height lets it, so towers stand out from the low buildings around them; the unscreened buildings have no measured height and cast none. 64-74 Franklin St is outlined in its own score color at the outline it covers at ground level. Dashed inside it is the typical floor, the one the floor-plate figure below draws, because this building steps back as it rises. Its windowless core is hatched. The inset places it among every building the screen covers.

Typical floor plan: 91% of the building’s floor area sits within daylight reach of a facade; the drawing shows its typical floor, where the share is 90%. The shading is daylight, darkest at the windows and gone 35 ft in. The hatched area is windowless core: 1,180 sq ft per typical floor that must be renovated but can never be rented as an apartment. The dimension marks the deepest interior point, 47 ft from the nearest window. A–A is where the section beside it is cut.

Section A–A: cut across the depth of the plate, through the middle of the core. Daylight reaches 35 ft in from every facade, fading as it goes, and the hatched stripe left between the lit edges is floor that gets converted and can never be rented: 1,180 sq ft on the floor the screen scores, and 8,776 sq ft over 9 residential floors. The steps are where the building sets back as it rises. The shaded ground floor is converted like the rest and counted as no homes.

This building's conversion pencils at default assumptions without any subsidy.

Across its 9 residential floors this building carries 8,776 sq ft of windowless core — area that must be gutted, re-plumbed and sprinklered but can never be rented as an apartment.

Modeled conversion metrics for 64-74 Franklin St, 2026-10-04.

Suitability scoreStrong candidate	90 / 100
Storiesfrom 124 ft aerial-survey height ÷ 12 ft floor-to-floor	10
Height bandsfloor plate by floor range, from the city's roof outlines	Floors 1–6: 11,312 sq ft · Floors 7–10: 10,104 sq ft
Floor platetypical floor, from the city outlines	11,312 sq ft
Daylight efficiencyshare within 35 ft of a facade	91%
Deepest interior pointviability threshold is 80 ft	47 ft
Windowless coretypical floor; the building-wide total is in the text above	1,180 sq ft
Estimated homesat 750 sq ft average	94
Conversion cost$360/sq ft all-in on 96,977 sq ft	$34.9M
Gap before grantpencils unsubsidized	-$6.6M
Modeled RESIDE grantbelow the statutory cap	$5.6M
BuiltBoston's own record of the construction year	1910
ZoningDowntown Boston	SKY
Opportunity Zonenot in a 2018 designated tract	No

The plan: window line, shape and floor rhythm

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

The typical floor has 440 ft of exterior wall, and across 9 residential floors the building carries 3,956 ft of it in total, divided among the 94 homes this screen estimates.

Its plate is compact at 0.74: 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 10.4 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 64-74 Franklin St scores 90 out of 100

Daylight efficiency 100, Interior depth 82, Scale 63, Finance 100 — each out of 100, then weighted.

Score components for 64-74 Franklin St. Points are the subscore times its weight.

Component	Subscore	Weight	Points
Daylight efficiency91% of the floor area within 35 ft of a facade, scored from 40% up to 90%	100	45%	45.0
Interior depthdeepest interior point 47 ft from a facade, scored from 80 ft down to 40 ft	82	25%	20.5
Scale94 estimated homes, scored from 0 up to 150	63	15%	9.4
Financecompleted value covers conversion cost with 35% to spare, which tops out the component	100	15%	15.0

Most of what it earns comes from daylight efficiency, and what holds it back most is scale, at 63 out of 100: 94 estimated homes, scored from 0 up to 150.

Built in 1910

Boston records this building as going up in 1910, which puts it in the pre-1920 stock.

As a rule, the era that converts most readily: load-bearing masonry, small floor plates laid out before deep-plan offices were possible, operable windows and generous floor-to-floor heights. The usual obstacles are not daylight but hazardous materials, lifts and bringing structure up to current code. 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 91% daylight figure above deserves.

What the conversion would cost

$360 per square foot all-in across 96,977 sq ft of converted floor, or $34.9M in total — about $371K for each of the 94 homes.

All-in cost per square foot for 64-74 Franklin St: base cost plus the code work a change of use triggers.

Base conversion cost	$260/sq ft
Plumbing risers to every unit	$40/sq ft
Operable windows and glazing	$30/sq ft
Additional egress stair	$18/sq ft
Fire sprinklers (NFPA 13R)	$12/sq ft
All-in	$360/sq ft

That cost is charged across every converted square foot, including the 8,776 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 94 homes is $41.5M.

What would have to be true

This one already clears the bar. The question is how much room it has before it stops.

At $442K a home, completed value covers the $34.9M of work with $6.6M to spare. Value per home would have to fall to $371K — 16% below the assumption — before the conversion stopped penciling, or all-in cost would have to rise from $360 to $428 per square foot. Neither is a wide margin in a market that moves, but this building does not need a grant to work.

Each of these, moved on its own, would be enough to undo that for 64-74 Franklin St:

Single-assumption flip points for 64-74 Franklin St, each holding the other three at their defaults.

Circulation efficiencythe binding constraint — the least this building would need	26% downto 60%
Completed value per home	29% downto $311K
Average unit size	34% upto 1,008 sq ft
Conversion cost per square foot	49% upto $386/sq ft

All four are sliders in the survey, where 64-74 Franklin St re-scores against your own numbers.

How it compares in Downtown Boston

64-74 Franklin St ranks 36th of the 96 buildings screened here, against a median score of 89.

Its floor plate is better lit than 54% of them, and shallower than 56% of them at its deepest interior point. On size it is the 64th 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

18th of 52 zoned SKY — the comparison that shares its rules, rents and streets.

52 of the screened buildings are zoned SKY. 64-74 Franklin St ranks 18th 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 47 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: 177 Milk St

The screened building closest to 64-74 Franklin St in converted floor area is 177 Milk St: 100,254 sq ft over 10 stories, against 96,977 sq ft over 10 here.

The two land within a few points of each other — 90 here, 89 there — so at this size the screen reads them as much the same prospect. On the money they sit in the same place: each pencils without a subsidy. The two stand about 1,800 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 64-74 Franklin St $5.6M, 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 64-74 Franklin St

The 4 closest the screen also covers, from 100 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 100 ft away
33 Arch St
34 stories · 72% daylit · 620 estimated homes · scores 71/100 (Strong candidate)
about 150 ft away
181-185 Devonshire St
10 stories · 100% daylit · 68 estimated homes · scores 92/100 (Strong candidate)
about 170 ft away
77 Franklin St
11 stories · 100% daylit · 77 estimated homes · scores 93/100 (Strong candidate)
about 220 ft away

A screen, not a feasibility study, from outlines and heights rather than plans: the method and how to correct a figure. If you know this building’s interior, you know what this model cannot see.