1101 Market St
1101 Market St is a 32-story building in Center City Philadelphia with 67% of its floor area within daylight reach of a facade. This screen estimates 846 homes and scores it 50 out of 100 for office-to-residential conversion suitability.
PA-2 & PA-3 · Screened 2026-09-15 · Worth a feasibility study
Also addressed as 1103 Market St, 1105 Market St, 1107 Market St, 1109 Market St and 1111 Market St: Philadelphia’s address records place all 6 on this one footprint.
Where 1101 Market St is
Its block in Center City Philadelphia, drawn from Philadelphia's own building outlines and street centerlines.
- Already housing
- Not screened
- 1101 Market St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Every floor carries 12,850 sq ft of windowless core — area that must be gutted, re-plumbed and sprinklered but can never be rented as an apartment. Across 31 residential floors that is 398,360 sq ft of cost carrying no revenue.
Modeled conversion metrics for 1101 Market St, 2026-09-15.
| Suitability scoreWorth a feasibility study | 50 / 100 |
|---|---|
| Storiesfrom 428 ft LiDAR height ÷ 12 ft floor-to-floor | 32 |
| Floor plateper floor, from the city footprint | 38,463 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 67% |
| Deepest interior pointviability threshold is 80 ft | 62 ft |
| Windowless coreper floor — renovated but never rentable | 12,850 sq ft |
| Estimated homesat 750 sq ft average | 846 |
| Conversion cost$360/sq ft all-in on 1,192,353 sq ft | $429.2M |
| Gap before grantshortfall against completed value | $262.8M |
| Modeled RESIDE grantat the statutory per-award cap | $10.0M |
| BuiltPhiladelphia's own record of the construction year | 1984 |
| ZoningCenter City Philadelphia | CMX5 |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
32 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 871 ft of exterior wall, and across 31 residential floors the building carries 26,989 ft of it in total, divided among the 846 homes this screen estimates.
Its plate is moderately compact at 0.64: 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 27.3 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 1101 Market St scores 50 out of 100
Daylight efficiency 53, Interior depth 45, Scale 100, Finance 2 — each out of 100, then weighted.
Score components for 1101 Market St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency67% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 53 | 45% | 23.9 |
| Interior depthdeepest interior point 62 ft from a facade, scored from 80 ft down to 40 ft | 45 | 25% | 11.2 |
| Scale846 estimated homes, scored from 0 up to 150 | 100 | 15% | 15.0 |
| Financeremaining gap is 59% of conversion cost, scored from 60% down to 0% | 2 | 15% | 0.3 |
Most of what it earns comes from daylight efficiency, and what holds it back most is finance, at 2 out of 100: remaining gap is 59% of conversion cost, scored from 60% down to 0%.
Built in 1984
Philadelphia records this building as going up in 1984, 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 67% daylight figure above deserves.
What the conversion would cost
$360 per square foot all-in across 1,192,353 sq ft of converted floor, or $429.2M in total — about $507K for each of the 846 homes.
All-in cost per square foot for 1101 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 398,360 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 846 homes is $166.4M.
What would have to be true
A $262.8M gap before any grant, $252.8M after the modeled one. The smallest single change that would close it: average unit size 60% down.
The shortfall before any grant is $262.8M. Closing it from the value side means each of the 846 homes finishing at $507K rather than the $197K the model assumes — 158% more. Closing it from the cost side means getting all-in cost down from $360 to $140 per square foot.
A modeled RESIDE grant of $10.0M moves that threshold to $496K a home. That is still above the $197K assumed, leaving $252.8M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 1101 Market St, one alone would close the gap at:
Single-assumption flip points for 1101 Market St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 60% downto 298 sq ft |
|---|---|
| Conversion cost per square foot | 82% downto $48/sq ft |
| Completed value per home | 152% upto $496K |
All four are sliders in the survey, where 1101 Market St re-scores against your own numbers.
How it compares in Center City Philadelphia
1101 Market St ranks 66th of the 103 buildings screened here, against a median score of 67.
Its floor plate is better lit than 28% of them, and shallower than 44% of them at its deepest interior point. On size it is the 12th 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
40th of 65 zoned CMX5 — the comparison that shares its rules, rents and streets.
65 of the screened buildings are zoned CMX5. 1101 Market St ranks 40th 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 62 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: 100 N 18th St
The screened building closest to 1101 Market St in converted floor area is 100 N 18th St: 1,150,615 sq ft over 34 stories, against 1,192,353 sq ft over 32 here.
The two land within a few points of each other — 50 here, 48 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 3,400 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 1101 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 1101 Market St
The 4 closest the screen also covers, from 520 ft away. They are the colored outlines on the plan at the top of this page.
- 15 S 11th St5 stories · 98% daylit · 27 estimated homes · scores 81/100 (Strong candidate)about 520 ft away
- 34 S 11th St8 stories · 75% daylit · 159 estimated homes · scores 67/100 (Worth a feasibility study)about 530 ft away
- 1234 Market St20 stories · 62% daylit · 461 estimated homes · scores 37/100 (Marginal)about 720 ft away
- 1207 Chestnut St7 stories · 100% daylit · 40 estimated homes · scores 83/100 (Strong candidate)about 800 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.