15 S 11th St

Where 15 S 11th St is

Its block in Center City Philadelphia, drawn from Philadelphia's own building outlines and street centerlines.

The plan: window line, shape and floor rhythm

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

The typical floor has 331 ft of exterior wall, and across 4 residential floors the building carries 1,322 ft of it in total, divided among the 27 homes this screen estimates.

Its plate is compact at 0.77: 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 6.8 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 15 S 11th St scores 81 out of 100

Daylight efficiency 100, Interior depth 100, Scale 18, Finance 54 — each out of 100, then weighted.

Most of what it earns comes from daylight efficiency, and what holds it back most is scale, at 18 out of 100: 27 estimated homes, scored from 0 up to 150.

Built in 1900

Philadelphia records this building as going up in 1900, 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 98% daylight figure above deserves.

What the conversion would cost

$360 per square foot all-in across 26,674 sq ft of converted floor, or $9.6M in total — about $356K for each of the 27 homes.

That cost is charged across every converted square foot, including the 435 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 27 homes is $5.3M.

What would have to be true

A $4.3M gap before any grant, $2.7M after the modeled one. The smallest single change that would close it: average unit size 26% down.

The shortfall before any grant is $4.3M. Closing it from the value side means each of the 27 homes finishing at $356K rather than the $197K the model assumes — 81% more. Closing it from the cost side means getting all-in cost down from $360 to $199 per square foot.

A modeled RESIDE grant of $1.6M moves that threshold to $296K a home. That is still above the $197K assumed, leaving $2.7M uncovered, which is why the grant does not unlock this one.

Nor do all four levers have to move. For 15 S 11th St, one alone would close the gap at:

All four are sliders in the survey, where 15 S 11th St re-scores against your own numbers.

How it compares in Center City Philadelphia

15 S 11th St ranks 35th of the 103 buildings screened here, against a median score of 67.

Its floor plate is better lit than 82% of them, and shallower than 79% of them at its deepest interior point. On size it is the 102nd 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

26th of 65 zoned CMX5 — the comparison that shares its rules, rents and streets.

65 of the screened buildings are zoned CMX5. 15 S 11th St ranks 26th 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 38 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: 2131 Arch St

The screened building closest to 15 S 11th St in converted floor area is 2131 Arch St: 27,579 sq ft over 4 stories, against 26,674 sq ft over 5 here.

15 S 11th St scores 81 to its 76, and with the size held roughly equal most of that lead comes from interior depth: 100 out of 100 here, 83 there (deepest interior point 47 ft from a facade, scored from 80 ft down to 40 ft). On the money they sit in the same place: each falls short even with the modeled grant. The two stand about 5,300 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 15 S 11th St $1.6M, 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 15 S 11th 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.

• 34 S 11th St
  8 stories · 75% daylit · 159 estimated homes · scores 67/100 (Worth a feasibility study)
  about 200 ft away
• 1101 Market St
  32 stories · 67% daylit · 846 estimated homes · scores 50/100 (Worth a feasibility study)
  about 520 ft away
• 917 Chestnut St
  9 stories · 79% daylit · 257 estimated homes · scores 64/100 (Worth a feasibility study)
  about 530 ft away
• 1207 Chestnut St
  7 stories · 100% daylit · 40 estimated homes · scores 83/100 (Strong candidate)
  about 620 ft away