100 1st St
100 1st St is a 27-story building in Downtown San Francisco with 73% of its floor area within daylight reach of a facade. This screen estimates 443 homes and scores it 60 out of 100 for office-to-residential conversion suitability.
CA-11 · Screened 2026-10-12 · Worth a feasibility study
Also addressed as 104 1st St, 110 1st St, 112 1st St, 116 1st St, 118 1st St and 519 Mission St: San Francisco’s address records place all 7 on this one footprint.
Where 100 1st St is
Its block in Downtown San Francisco, drawn from San Francisco's own building outlines and street centerlines.
- Already housing
- Not screened
- 100 1st St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Every floor carries 5,982 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 26 residential floors that is 155,545 sq ft of cost carrying no revenue.
Modeled conversion metrics for 100 1st St, 2026-10-12.
| Suitability scoreWorth a feasibility study | 60 / 100 |
|---|---|
| Storiesfrom 339 ft LiDAR (2010) height ÷ 12 ft floor-to-floor | 27 |
| Floor plateper floor, from the city footprint | 21,957 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 73% |
| Deepest interior pointviability threshold is 80 ft | 69 ft |
| Windowless coreper floor — renovated but never rentable | 5,982 sq ft |
| Estimated homesat 750 sq ft average | 443 |
| Conversion cost$405/sq ft all-in on 570,885 sq ft | $231.2M |
| Gap before grantshortfall against completed value | $69.1M |
| Modeled RESIDE grantat the statutory per-award cap | $10.0M |
| BuiltSan Francisco's own record of the construction year | 1988 |
| ZoningFinancial District/South Beach | C-3-O(SD) |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
38 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 641 ft of exterior wall, and across 26 residential floors the building carries 16,669 ft of it in total, divided among the 443 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 17.0 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 100 1st St scores 60 out of 100
Daylight efficiency 66, Interior depth 28, Scale 100, Finance 57 — each out of 100, then weighted.
Score components for 100 1st St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency73% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 66 | 45% | 29.5 |
| Interior depthdeepest interior point 69 ft from a facade, scored from 80 ft down to 40 ft | 28 | 25% | 7.0 |
| Scale443 estimated homes, scored from 0 up to 150 | 100 | 15% | 15.0 |
| 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 interior depth, at 28 out of 100: deepest interior point 69 ft from a facade, scored from 80 ft down to 40 ft.
Built in 1988
San Francisco records this building as going up in 1988, 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 73% daylight figure above deserves.
What the conversion would cost
$405 per square foot all-in across 570,885 sq ft of converted floor, or $231.2M in total — about $522K for each of the 443 homes.
All-in cost per square foot for 100 1st St: base cost plus the code work a change of use triggers.
| Base conversion cost | $260/sq ft |
|---|---|
| Seismic retrofit (change of use) | $45/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 | $405/sq ft |
That cost is charged across every converted square foot, including the 155,545 sq ft of windowless core, which has to be gutted, seismically braced and sprinklered like the rest of the building and then earns nothing. Against it the model sets a completed value of $366K a home, which for 443 homes is $162.1M.
What would have to be true
A $69.1M gap before any grant, $59.1M after the modeled one. The smallest single change that would close it: average unit size 27% down.
The shortfall before any grant is $69.1M. Closing it from the value side means each of the 443 homes finishing at $522K rather than the $366K the model assumes — 43% more. Closing it from the cost side means getting all-in cost down from $405 to $284 per square foot.
A modeled RESIDE grant of $10.0M moves that threshold to $499K a home. That is still above the $366K assumed, leaving $59.1M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 100 1st St, one alone would close the gap at:
Single-assumption flip points for 100 1st St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 27% downto 549 sq ft |
|---|---|
| Completed value per home | 36% upto $499K |
| Conversion cost per square foot | 40% downto $157/sq ft |
All four are sliders in the survey, where 100 1st St re-scores against your own numbers.
How it compares in Downtown San Francisco
100 1st St ranks 177th of the 205 buildings screened here, against a median score of 87.
Its floor plate is better lit than 15% of them, and shallower than 13% of them at its deepest interior point. On size it is the 27th largest by estimated homes. The full survey of all 205 buildings ranks and maps every one of them, and the list by address links each to its own page.
Within Financial District/South Beach and the C-3-O(SD) zone
145th of 165 in Financial District/South Beach, 52nd of 66 zoned C-3-O(SD) — the comparison that shares its rules, rents and streets.
San Francisco places 165 of the screened buildings in Financial District/South Beach. 100 1st St ranks 145th of them against a median score of 88. 121 score 70 or more, their median deepest interior point is 47 ft from a facade against this building’s 69 ft, and together they would hold an estimated 40,456 homes. The group’s top scorer is 870 Market St, at 100.
66 of the screened buildings are zoned C-3-O(SD). 100 1st St ranks 52nd of them against a median score of 72. 37 score 70 or more, their median deepest interior point is 59 ft from a facade against this building’s 69 ft, and together they would hold an estimated 18,546 homes. The group’s top scorer is 140 New Montgomery St, at 100.
Its nearest match in size: 440 Sutter St
The screened building closest to 100 1st St in converted floor area is 440 Sutter St: 592,060 sq ft over 26 stories, against 570,885 sq ft over 27 here.
The two land within a few points of each other — 60 here, 62 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 3,000 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 100 1st 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 100 1st St
The 4 closest the screen also covers, from 230 ft away. They are the colored outlines on the plan at the top of this page.
- 535 Mission St27 stories · 86% daylit · 361 estimated homes · scores 88/100 (Strong candidate)about 230 ft away
- 101 1st St63 stories · 59% daylit · 1,457 estimated homes · scores 35/100 (Marginal)about 250 ft away
- 440 Mission St5 stories · 82% daylit · 51 estimated homes · scores 70/100 (Strong candidate)about 310 ft away
- 25 Jessie St17 stories · 99% daylit · 109 estimated homes · scores 96/100 (Strong candidate)about 340 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.