1619 Walnut St
1619 Walnut St is a 6-story building in Center City Philadelphia with 100% of its floor area within daylight reach of a facade. This screen estimates 33 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 1621 Walnut St: Philadelphia’s address records place both on this one footprint.
Where 1619 Walnut St is
Its block in Center City Philadelphia, drawn from Philadelphia's own building outlines and street centerlines.
- Already housing
- Not screened
- 1619 Walnut St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
This footprint has no windowless core at all: every point on the floor plate is within 35 ft of a facade, which is unusual and is the main reason it scores as well as it does.
Modeled conversion metrics for 1619 Walnut St, 2026-09-15.
| Suitability scoreStrong candidate | 82 / 100 |
|---|---|
| Storiesfrom 111 ft LiDAR height ÷ 12 ft floor-to-floor | 6 |
| Floor plateper floor, from the city footprint | 6,322 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 100% |
| Deepest interior pointviability threshold is 80 ft | 26 ft |
| Windowless coreper floor — renovated but never rentable | 0 sq ft |
| Estimated homesat 750 sq ft average | 33 |
| Conversion cost$360/sq ft all-in on 31,610 sq ft | $11.4M |
| Gap before grantshortfall against completed value | $4.9M |
| Modeled RESIDE grantbelow the statutory cap | $2.0M |
| BuiltPhiladelphia's own record of the construction year | 1937 |
| ZoningCenter City Philadelphia | CMX5 |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
52 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 345 ft of exterior wall, and across 5 residential floors the building carries 1,726 ft of it in total, divided among the 33 homes this screen estimates.
Its plate is moderately compact at 0.67: 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 6.6 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 1619 Walnut St scores 82 out of 100
Daylight efficiency 100, Interior depth 100, Scale 22, Finance 57 — each out of 100, then weighted.
Score components for 1619 Walnut St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency100% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 100 | 45% | 45.0 |
| Interior depthdeepest interior point 26 ft from a facade, scored from 80 ft down to 40 ft | 100 | 25% | 25.0 |
| Scale33 estimated homes, scored from 0 up to 150 | 22 | 15% | 3.3 |
| Financeremaining gap is 26% of conversion cost, scored from 60% down to 0% | 57 | 15% | 8.6 |
Most of what it earns comes from daylight efficiency, and what holds it back most is scale, at 22 out of 100: 33 estimated homes, scored from 0 up to 150.
Built in 1937
Philadelphia records this building as going up in 1937, 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 100% daylight figure above deserves.
What the conversion would cost
$360 per square foot all-in across 31,610 sq ft of converted floor, or $11.4M in total — about $345K for each of the 33 homes.
All-in cost per square foot for 1619 Walnut 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 circulation and service area that earns nothing directly. Against it the model sets a completed value of $197K a home, which for 33 homes is $6.5M.
What would have to be true
A $4.9M gap before any grant, $2.9M after the modeled one. The smallest single change that would close it: average unit size 25% down.
The shortfall before any grant is $4.9M. Closing it from the value side means each of the 33 homes finishing at $345K rather than the $197K the model assumes — 75% more. Closing it from the cost side means getting all-in cost down from $360 to $205 per square foot.
A modeled RESIDE grant of $2.0M moves that threshold to $285K a home. That is still above the $197K assumed, leaving $2.9M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 1619 Walnut St, one alone would close the gap at:
Single-assumption flip points for 1619 Walnut St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 25% downto 562 sq ft |
|---|---|
| Conversion cost per square foot | 35% downto $168/sq ft |
| Completed value per home | 45% upto $285K |
All four are sliders in the survey, where 1619 Walnut St re-scores against your own numbers.
How it compares in Center City Philadelphia
1619 Walnut St ranks 29th of the 103 buildings screened here, against a median score of 67.
Its floor plate is better lit than 100% of them, and shallower than 94% of them at its deepest interior point. On size it is the 100th 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
22nd of 65 zoned CMX5 — the comparison that shares its rules, rents and streets.
65 of the screened buildings are zoned CMX5. 1619 Walnut St ranks 22nd 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 26 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: 1524 Chestnut St
The screened building closest to 1619 Walnut St in converted floor area is 1524 Chestnut St: 30,723 sq ft over 4 stories, against 31,610 sq ft over 6 here.
The two land within a few points of each other — 82 here, 82 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 500 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 1619 Walnut St $2.0M, 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 1619 Walnut 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.
- 1601 Walnut St15 stories · 95% daylit · 140 estimated homes · scores 92/100 (Strong candidate)about 200 ft away
- 1524 Walnut St21 stories · 86% daylit · 249 estimated homes · scores 81/100 (Strong candidate)about 380 ft away
- 1524 Chestnut St4 stories · 100% daylit · 32 estimated homes · scores 82/100 (Strong candidate)about 520 ft away
- 1525 Locust St18 stories · 100% daylit · 121 estimated homes · scores 91/100 (Strong candidate)about 570 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.