1900 Market St
1900 Market St is a 9-story building in Center City Philadelphia with 51% of its floor area within daylight reach of a facade. This screen estimates 299 homes and scores it 25 out of 100 for office-to-residential conversion suitability.
PA-2 & PA-3 · Screened 2026-09-15 · Unlikely
Where 1900 Market St is
Its block in Center City Philadelphia, drawn from Philadelphia's own building outlines and street centerlines.
- Already housing
- Not screened
- 1900 Market St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Every floor carries 34,169 sq ft of windowless core — area that must be gutted, re-plumbed and sprinklered but can never be rented as an apartment. Across 8 residential floors that is 273,351 sq ft of cost carrying no revenue.
Modeled conversion metrics for 1900 Market St, 2026-09-15.
| Suitability scoreUnlikely | 25 / 100 |
|---|---|
| Storiesfrom 117 ft LiDAR height ÷ 12 ft floor-to-floor | 9 |
| Floor plateper floor, from the city footprint | 69,228 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 51% |
| Deepest interior pointviability threshold is 80 ft | 88 ft |
| Windowless coreper floor — renovated but never rentable | 34,169 sq ft |
| Estimated homesat 750 sq ft average | 299 |
| Conversion cost$360/sq ft all-in on 553,823 sq ft | $199.4M |
| Gap before grantshortfall against completed value | $140.6M |
| Modeled RESIDE grantat the statutory per-award cap | $10.0M |
| BuiltPhiladelphia's own record of the construction year | 1981 |
| ZoningCenter City Philadelphia | CMX5 |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
31 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 1,149 ft of exterior wall, and across 8 residential floors the building carries 9,190 ft of it in total, divided among the 299 homes this screen estimates.
Its plate is moderately compact at 0.66: 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 37.4 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 1900 Market St scores 25 out of 100
Daylight efficiency 21, Interior depth 0, Scale 100, Finance 0 — each out of 100, then weighted.
Score components for 1900 Market St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency51% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 21 | 45% | 9.6 |
| Interior depthdeepest interior point 88 ft from a facade, scored from 80 ft down to 40 ft | 0 | 25% | 0.0 |
| Scale299 estimated homes, scored from 0 up to 150 | 100 | 15% | 15.0 |
| Financeremaining gap is 65% of conversion cost, scored from 60% down to 0% | 0 | 15% | 0.0 |
Most of what it earns comes from scale, and what holds it back most is interior depth, at 0 out of 100: deepest interior point 88 ft from a facade, scored from 80 ft down to 40 ft.
Built in 1981
Philadelphia records this building as going up in 1981, which puts it in the late-modern stock.
As a rule, typically the hardest to convert: the deepest plates of any era, large central cores, and floor-to-floor heights tight enough that running residential drainage under a ceiling can be the thing that ends a project. 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 51% daylight figure above deserves.
What the conversion would cost
$360 per square foot all-in across 553,823 sq ft of converted floor, or $199.4M in total — about $667K for each of the 299 homes.
All-in cost per square foot for 1900 Market 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 273,351 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 $197K a home, which for 299 homes is $58.8M.
What would have to be true
A $140.6M gap before any grant, $130.6M after the modeled one. The smallest single change that would close it: average unit size 69% down.
The shortfall before any grant is $140.6M. Closing it from the value side means each of the 299 homes finishing at $667K rather than the $197K the model assumes — 239% more. Closing it from the cost side means getting all-in cost down from $360 to $106 per square foot.
A modeled RESIDE grant of $10.0M moves that threshold to $633K a home. That is still above the $197K assumed, leaving $130.6M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 1900 Market St, one alone would close the gap at:
Single-assumption flip points for 1900 Market St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 69% downto 233 sq ft |
|---|---|
| Conversion cost per square foot | 91% downto $24/sq ft |
| Completed value per home | 222% upto $633K |
All four are sliders in the survey, where 1900 Market St re-scores against your own numbers.
How it compares in Center City Philadelphia
1900 Market St ranks 98th of the 103 buildings screened here, against a median score of 67.
Its floor plate is better lit than 6% of them, and shallower than 13% of them at its deepest interior point. On size it is the 38th largest by estimated homes. The full survey of all 103 buildings ranks and maps every one of them, and the list by address links each to its own page.
Within the CMX5 zone
62nd of 65 zoned CMX5 — the comparison that shares its rules, rents and streets.
65 of the screened buildings are zoned CMX5. 1900 Market St ranks 62nd of them against a median score of 67. 28 score 70 or more, their median deepest interior point is 58 ft from a facade against this building’s 88 ft, and together they would hold an estimated 30,650 homes. The group’s top scorer is 112 N Broad St, at 93.
Its nearest match in size: 701 Market St
The screened building closest to 1900 Market St in converted floor area is 701 Market St: 578,406 sq ft over 5 stories, against 553,823 sq ft over 9 here.
1900 Market St scores 25 to its 15, and with the size held roughly equal most of that lead comes from daylight efficiency: 21 out of 100 here, 0 there (40% of the floor area within 35 ft of a facade, scored from 40% up to 90%). On the money they sit in the same place: each falls short even with the modeled grant. The two stand about 5,500 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 1900 Market 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 1900 Market St
The 4 closest the screen also covers, from 290 ft away. They are the colored outlines on the plan at the top of this page.
- 1901 Market St45 stories · 70% daylit · 1,009 estimated homes · scores 35/100 (Marginal)about 290 ft away
- 2000 Market St29 stories · 66% daylit · 577 estimated homes · scores 42/100 (Marginal)about 330 ft away
- 1818 Market St40 stories · 62% daylit · 852 estimated homes · scores 35/100 (Marginal)about 400 ft away
- 1835 Market St29 stories · 63% daylit · 565 estimated homes · scores 36/100 (Marginal)about 430 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.