319 N 11th St
319 N 11th St is a 6-story building in Center City Philadelphia with 95% of its floor area within daylight reach of a facade. This screen estimates 44 homes and scores it 82 out of 100 for office-to-residential conversion suitability.
PA-2 & PA-3 · Screened 2026-09-15 · Strong candidate
Also addressed as 321 N 11th St, 323 N 11th St and 325 N 11th St: Philadelphia’s address records place all 4 on this one footprint.
Where 319 N 11th St is
Its block in Center City Philadelphia, drawn from Philadelphia's own building outlines and street centerlines.
- Already housing
- Not screened
- 319 N 11th St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Every floor carries 437 sq ft of windowless core — area that must be gutted, re-plumbed and sprinklered but can never be rented as an apartment. Across 5 residential floors that is 2,185 sq ft of cost carrying no revenue.
Modeled conversion metrics for 319 N 11th St, 2026-09-15.
| Suitability scoreStrong candidate | 82 / 100 |
|---|---|
| Storiesfrom 85 ft LiDAR height ÷ 12 ft floor-to-floor | 6 |
| Floor plateper floor, from the city footprint | 8,860 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 95% |
| Deepest interior pointviability threshold is 80 ft | 40 ft |
| Windowless coreper floor — renovated but never rentable | 437 sq ft |
| Estimated homesat 750 sq ft average | 44 |
| Conversion cost$360/sq ft all-in on 44,302 sq ft | $15.9M |
| Gap before grantshortfall against completed value | $7.3M |
| Modeled RESIDE grantbelow the statutory cap | $2.6M |
| BuiltPhiladelphia's own record of the construction year | 1920 |
| ZoningCenter City Philadelphia | IRMX |
| Opportunity Zonecensus tract 42101037600, 2018 designation | Yes |
The plan: window line, shape and floor rhythm
44 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 390 ft of exterior wall, and across 5 residential floors the building carries 1,948 ft of it in total, divided among the 44 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 8.8 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 319 N 11th St scores 82 out of 100
Daylight efficiency 100, Interior depth 99, Scale 29, Finance 51 — each out of 100, then weighted.
Score components for 319 N 11th St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency95% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 100 | 45% | 45.0 |
| Interior depthdeepest interior point 40 ft from a facade, scored from 80 ft down to 40 ft | 99 | 25% | 24.7 |
| Scale44 estimated homes, scored from 0 up to 150 | 29 | 15% | 4.4 |
| Financeremaining gap is 29% of conversion cost, scored from 60% down to 0% | 51 | 15% | 7.7 |
Most of what it earns comes from daylight efficiency, and what holds it back most is scale, at 29 out of 100: 44 estimated homes, scored from 0 up to 150.
Built in 1920
Philadelphia 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 95% daylight figure above deserves.
What the conversion would cost
$360 per square foot all-in across 44,302 sq ft of converted floor, or $15.9M in total — about $362K for each of the 44 homes.
All-in cost per square foot for 319 N 11th 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 2,185 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 44 homes is $8.7M.
What would have to be true
A $7.3M gap before any grant, $4.7M after the modeled one. The smallest single change that would close it: average unit size 29% down.
The shortfall before any grant is $7.3M. Closing it from the value side means each of the 44 homes finishing at $362K rather than the $197K the model assumes — 84% more. Closing it from the cost side means getting all-in cost down from $360 to $195 per square foot.
A modeled RESIDE grant of $2.6M moves that threshold to $302K a home. That is still above the $197K assumed, leaving $4.7M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 319 N 11th St, one alone would close the gap at:
Single-assumption flip points for 319 N 11th St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 29% downto 535 sq ft |
|---|---|
| Conversion cost per square foot | 40% downto $155/sq ft |
| Completed value per home | 54% upto $302K |
All four are sliders in the survey, where 319 N 11th St re-scores against your own numbers.
How it compares in Center City Philadelphia
319 N 11th St ranks 30th of the 103 buildings screened here, against a median score of 67.
Its floor plate is better lit than 75% of them, and shallower than 75% of them at its deepest interior point. On size it is the 88th 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.
Its nearest match in size: 901 Arch St
The screened building closest to 319 N 11th St in converted floor area is 901 Arch St: 44,132 sq ft over 7 stories, against 44,302 sq ft over 6 here.
The two land within a few points of each other — 82 here, 84 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 1,800 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 319 N 11th St $2.6M, 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.
This building does sit in census tract 42101037600, a 2018 designated Opportunity Zone, which Section 201 lets HUD favor — one of the few statutory priorities this screen can actually check.
Other buildings screened near 319 N 11th St
The 4 closest the screen also covers, from 310 ft away. They are the colored outlines on the plan at the top of this page.
- 1025 Callowhill St5 stories · 88% daylit · 50 estimated homes · scores 73/100 (Strong candidate)about 310 ft away
- 448 N 10th St7 stories · 100% daylit · 52 estimated homes · scores 84/100 (Strong candidate)about 920 ft away
- 211 N 13th St9 stories · 92% daylit · 78 estimated homes · scores 81/100 (Strong candidate)about 1,220 ft away
- 990 Spring Garden St7 stories · 76% daylit · 109 estimated homes · scores 63/100 (Worth a feasibility study)about 1,290 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.