428 Walnut St

Where 428 Walnut 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

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 859 ft of exterior wall, and across 8 residential floors the building carries 6,873 ft of it in total, divided among the 212 homes this screen estimates.

Its plate is moderately compact at 0.57: 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 26.5 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 428 Walnut St scores 58 out of 100

Daylight efficiency 68, Interior depth 35, Scale 100, Finance 22 — each out of 100, then weighted.

Most of what it earns comes from daylight efficiency, and what holds it back most is finance, at 22 out of 100: remaining gap is 47% of conversion cost, scored from 60% down to 0%.

Built in 1924

Philadelphia records this building as going up in 1924, 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 74% daylight figure above deserves.

What the conversion would cost

$360 per square foot all-in across 269,107 sq ft of converted floor, or $96.9M in total — about $457K for each of the 212 homes.

That cost is charged across every converted square foot, including the 69,855 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 212 homes is $41.7M.

What would have to be true

A $55.2M gap before any grant, $45.2M after the modeled one. The smallest single change that would close it: average unit size 52% down.

The shortfall before any grant is $55.2M. Closing it from the value side means each of the 212 homes finishing at $457K rather than the $197K the model assumes — 132% more. Closing it from the cost side means getting all-in cost down from $360 to $155 per square foot.

A modeled RESIDE grant of $10.0M moves that threshold to $410K a home. That is still above the $197K assumed, leaving $45.2M uncovered, which is why the grant does not unlock this one.

Nor do all four levers have to move. For 428 Walnut St, one alone would close the gap at:

All four are sliders in the survey, where 428 Walnut St re-scores against your own numbers.

How it compares in Center City Philadelphia

428 Walnut St ranks 60th of the 103 buildings screened here, against a median score of 67.

Its floor plate is better lit than 40% of them, and shallower than 36% of them at its deepest interior point. On size it is the 52nd 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 CMX4 zone

8th of 15 zoned CMX4 — the comparison that shares its rules, rents and streets.

15 of the screened buildings are zoned CMX4. 428 Walnut St ranks 8th of them against a median score of 58. 5 score 70 or more, their median deepest interior point is 64 ft from a facade against this building’s 66 ft, and together they would hold an estimated 4,016 homes. The group’s top scorer is 901 Arch St, at 84.

Its nearest match in size: 421 N 7th St

The screened building closest to 428 Walnut St in converted floor area is 421 N 7th St: 252,495 sq ft over 7 stories, against 269,107 sq ft over 9 here.

428 Walnut St scores 58 to its 79, and with the size held roughly equal most of that shortfall comes from daylight efficiency: 68 out of 100 here, 90 there (85% 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 4,400 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 428 Walnut 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 428 Walnut St

The 4 closest the screen also covers, from 350 ft away. They are the colored outlines on the plan at the top of this page.

• 508 Walnut St
  20 stories · 48% daylit · 712 estimated homes · scores 23/100 (Unlikely)
  about 350 ft away
• 170 S Independence Mall W
  12 stories · 43% daylit · 476 estimated homes · scores 18/100 (Unlikely)
  about 810 ft away
• 325 Chestnut St
  13 stories · 87% daylit · 211 estimated homes · scores 80/100 (Strong candidate)
  about 930 ft away
• 105 S 7th St
  4 stories · 63% daylit · 66 estimated homes · scores 33/100 (Marginal)
  about 990 ft away