105 S 7th St
105 S 7th St is a 4-story building in Center City Philadelphia with 63% of its floor area within daylight reach of a facade. This screen estimates 66 homes and scores it 33 out of 100 for office-to-residential conversion suitability.
PA-2 & PA-3 · Screened 2026-09-15 · Marginal
Also addressed as 107 S 7th St, 109 S 7th St, 111 S 7th St, 113 S 7th St, 115 S 7th St and 117 S 7th St: Philadelphia’s address records place all 7 on this one footprint.
Where 105 S 7th St is
Its block in Center City Philadelphia, drawn from Philadelphia's own building outlines and street centerlines.
- Already housing
- Not screened
- 105 S 7th St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Every floor carries 11,952 sq ft of windowless core — area that must be gutted, re-plumbed and sprinklered but can never be rented as an apartment. Across 3 residential floors that is 35,857 sq ft of cost carrying no revenue.
Modeled conversion metrics for 105 S 7th St, 2026-09-15.
| Suitability scoreMarginal | 33 / 100 |
|---|---|
| Storiesfrom 86 ft LiDAR height ÷ 12 ft floor-to-floor | 4 |
| Floor plateper floor, from the city footprint | 32,734 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 63% |
| Deepest interior pointviability threshold is 80 ft | 75 ft |
| Windowless coreper floor — renovated but never rentable | 11,952 sq ft |
| Estimated homesat 750 sq ft average | 66 |
| Conversion cost$360/sq ft all-in on 98,203 sq ft | $35.4M |
| Gap before grantshortfall against completed value | $22.4M |
| Modeled RESIDE grantbelow the statutory cap | $4.0M |
| BuiltPhiladelphia's own record of the construction year | 1923 |
| ZoningCenter City Philadelphia | CMX5 |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
34 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 748 ft of exterior wall, and across 3 residential floors the building carries 2,243 ft of it in total, divided among the 66 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 22.0 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 105 S 7th St scores 33 out of 100
Daylight efficiency 47, Interior depth 12, Scale 44, Finance 13 — each out of 100, then weighted.
Score components for 105 S 7th St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency63% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 47 | 45% | 21.1 |
| Interior depthdeepest interior point 75 ft from a facade, scored from 80 ft down to 40 ft | 12 | 25% | 3.0 |
| Scale66 estimated homes, scored from 0 up to 150 | 44 | 15% | 6.6 |
| Financeremaining gap is 52% of conversion cost, scored from 60% down to 0% | 13 | 15% | 2.0 |
Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 12 out of 100: deepest interior point 75 ft from a facade, scored from 80 ft down to 40 ft.
Built in 1923
Philadelphia records this building as going up in 1923, 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 63% daylight figure above deserves.
What the conversion would cost
$360 per square foot all-in across 98,203 sq ft of converted floor, or $35.4M in total — about $536K for each of the 66 homes.
All-in cost per square foot for 105 S 7th 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 35,857 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 66 homes is $13.0M.
What would have to be true
A $22.4M gap before any grant, $18.4M after the modeled one. The smallest single change that would close it: average unit size 52% down.
The shortfall before any grant is $22.4M. Closing it from the value side means each of the 66 homes finishing at $536K rather than the $197K the model assumes — 172% more. Closing it from the cost side means getting all-in cost down from $360 to $132 per square foot.
A modeled RESIDE grant of $4.0M moves that threshold to $476K a home. That is still above the $197K assumed, leaving $18.4M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 105 S 7th St, one alone would close the gap at:
Single-assumption flip points for 105 S 7th St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 52% downto 361 sq ft |
|---|---|
| Conversion cost per square foot | 72% downto $73/sq ft |
| Completed value per home | 142% upto $476K |
All four are sliders in the survey, where 105 S 7th St re-scores against your own numbers.
How it compares in Center City Philadelphia
105 S 7th St ranks 91st of the 103 buildings screened here, against a median score of 67.
Its floor plate is better lit than 22% of them, and shallower than 27% of them at its deepest interior point. On size it is the 77th 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
57th of 65 zoned CMX5 — the comparison that shares its rules, rents and streets.
65 of the screened buildings are zoned CMX5. 105 S 7th St ranks 57th 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 75 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 20th St
The screened building closest to 105 S 7th St in converted floor area is 100 N 20th St: 88,866 sq ft over 5 stories, against 98,203 sq ft over 4 here.
105 S 7th St scores 33 to its 48, and with the size held roughly equal most of that shortfall comes from daylight efficiency: 47 out of 100 here, 67 there (74% 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 6,400 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 105 S 7th St $4.0M, 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 105 S 7th St
The 4 closest the screen also covers, from 200 ft away. They are the colored outlines on the plan at the top of this page.
- 700 Chestnut St6 stories · 100% daylit · 36 estimated homes · scores 83/100 (Strong candidate)about 200 ft away
- 170 S Independence Mall W12 stories · 43% daylit · 476 estimated homes · scores 18/100 (Unlikely)about 250 ft away
- 615 Chestnut St17 stories · 59% daylit · 466 estimated homes · scores 36/100 (Marginal)about 290 ft away
- 734 Sansom St6 stories · 95% daylit · 42 estimated homes · scores 79/100 (Strong candidate)about 550 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.