399 Market St

Where 399 Market 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

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

The typical floor has 666 ft of exterior wall, and across 4 residential floors the building carries 2,662 ft of it in total, divided among the 80 homes this screen estimates.

Its plate is compact at 0.79: 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 20.0 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 399 Market St scores 40 out of 100

Daylight efficiency 54, Interior depth 20, Scale 53, Finance 18 — each out of 100, then weighted.

Most of what it earns comes from daylight efficiency, and what holds it back most is finance, at 18 out of 100: remaining gap is 49% of conversion cost, scored from 60% down to 0%.

Built in 1977

Philadelphia records this building as going up in 1977, 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 111,989 sq ft of converted floor, or $40.3M in total — about $504K for each of the 80 homes.

That cost is charged across every converted square foot, including the 36,975 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 80 homes is $15.7M.

What would have to be true

A $24.6M gap before any grant, $19.8M after the modeled one. The smallest single change that would close it: average unit size 49% down.

The shortfall before any grant is $24.6M. Closing it from the value side means each of the 80 homes finishing at $504K rather than the $197K the model assumes — 156% more. Closing it from the cost side means getting all-in cost down from $360 to $141 per square foot.

A modeled RESIDE grant of $4.8M moves that threshold to $444K a home. That is still above the $197K assumed, leaving $19.8M uncovered, which is why the grant does not unlock this one.

Nor do all four levers have to move. For 399 Market St, one alone would close the gap at:

All four are sliders in the survey, where 399 Market St re-scores against your own numbers.

How it compares in Center City Philadelphia

399 Market St ranks 75th of the 103 buildings screened here, against a median score of 67.

Its floor plate is better lit than 30% of them, and shallower than 30% of them at its deepest interior point. On size it is the 72nd 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 CMX3 zone

14th of 14 zoned CMX3 — the comparison that shares its rules, rents and streets.

14 of the screened buildings are zoned CMX3. 399 Market St ranks 14th of them against a median score of 73. 8 score 70 or more, their median deepest interior point is 53 ft from a facade against this building’s 72 ft, and together they would hold an estimated 1,122 homes. The group’s top scorer is 461 N 3rd St, at 84.

Its nearest match in size: 417 N 8th St

The screened building closest to 399 Market St in converted floor area is 417 N 8th St: 114,725 sq ft over 5 stories, against 111,989 sq ft over 5 here.

399 Market St scores 40 to its 72, and with the size held roughly equal most of that shortfall comes from daylight efficiency: 54 out of 100 here, 89 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 3,300 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 399 Market St $4.8M, 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 399 Market St

The 4 closest the screen also covers, from 240 ft away. They are the colored outlines on the plan at the top of this page.

• 330 Market St
  4 stories · 77% daylit · 45 estimated homes · scores 53/100 (Worth a feasibility study)
  about 240 ft away
• 101 N Independence Mall E
  11 stories · 63% daylit · 327 estimated homes · scores 46/100 (Marginal)
  about 350 ft away
• 232 Market St
  5 stories · 100% daylit · 39 estimated homes · scores 83/100 (Strong candidate)
  about 580 ft away
• 325 Chestnut St
  13 stories · 87% daylit · 211 estimated homes · scores 80/100 (Strong candidate)
  about 580 ft away