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

Build a free conversion planCheck its numbers, lay out its homes and get a two-page PDF. Free.

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.

49 Stevenson St: scores 99 out of 10025 Jessie St: scores 96 out of 10040 Jessie St: scores 88 out of 100535 Mission St: scores 88 out of 100560 Mission St: scores 73 out of 10071 Stevenson St: scores 72 out of 100440 Mission St: scores 70 out of 100555 Market St: scores 66 out of 100555 Mission St: scores 60 out of 100500 Howard St: scores 52 out of 100525 Market St: scores 46 out of 100400 Howard St: scores 35 out of 100101 1st St: scores 35 out of 100235 1st St: scores 32 out of 10099968888706052353560MINNA STMISSION STNATOMA ST1ST STECKER STJESSIE STN100 ftDowntown San Francisco
Suitability score
0–29
30–49
50–69
70–100
  • Already housing
  • Not screened
  • 100 1st St
100 1st St and the 1,000 ft of Downtown San Francisco around it. The streets are drawn at the width of the right-of-way they run down, sidewalks included, and named, and every building on these blocks is drawn. What is left open and stippled is neither: a surface lot, a plaza or a vacant parcel. The screened buildings are colored by the ramp above, the same one the district map uses, carry their score, and each is a link to its own page. Each casts a shadow as long as its measured height lets it, so towers stand out from the low buildings around them; the unscreened buildings have no measured height and cast none. 100 1st St is outlined in its own score color at the outline it covers at ground level. Its windowless core is hatched. The inset places it among every building the screen covers.
69 ftAA50 ftDaylit 73%Core 5,982 sq ft
Floor plan: 73% of each floor sits within daylight reach of a facade. The shading is daylight, darkest at the windows and gone 35 ft in. The hatched area is windowless core: 5,982 sq ft per floor that must be renovated but can never be rented as an apartment. The dimension marks the deepest interior point, 69 ft from the nearest window. A–A is where the section beside it is cut.
Windowless core27 floors50 ft
Section A–A: cut across the depth of the plate, through the middle of the core. Daylight reaches 35 ft in from every facade, fading as it goes, and the hatched stripe left between the lit edges is floor that gets converted and can never be rented: 5,982 sq ft on the floor the screen scores, and 155,545 sq ft over 26 residential floors. The shaded ground floor is converted like the rest and counted as no homes.

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 study60 / 100
Storiesfrom 339 ft LiDAR (2010) height ÷ 12 ft floor-to-floor27
Floor plateper floor, from the city footprint21,957 sq ft
Daylight efficiencyshare within 35 ft of a facade73%
Deepest interior pointviability threshold is 80 ft69 ft
Windowless coreper floor — renovated but never rentable5,982 sq ft
Estimated homesat 750 sq ft average443
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 year1988
ZoningFinancial District/South BeachC-3-O(SD)
Opportunity Zonenot in a 2018 designated tractNo

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.

ComponentSubscoreWeightPoints
Daylight efficiency73% of the floor area within 35 ft of a facade, scored from 40% up to 90%6645%29.5
Interior depthdeepest interior point 69 ft from a facade, scored from 80 ft down to 40 ft2825%7.0
Scale443 estimated homes, scored from 0 up to 15010015%15.0
Financeremaining gap is 26% of conversion cost, scored from 60% down to 0%5715%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 need27% downto 549 sq ft
Completed value per home36% upto $499K
Conversion cost per square foot40% 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 St
    27 stories · 86% daylit · 361 estimated homes · scores 88/100 (Strong candidate)
    about 230 ft away
  • 101 1st St
    63 stories · 59% daylit · 1,457 estimated homes · scores 35/100 (Marginal)
    about 250 ft away
  • 440 Mission St
    5 stories · 82% daylit · 51 estimated homes · scores 70/100 (Strong candidate)
    about 310 ft away
  • 25 Jessie St
    17 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.