545 Sansome St
545 Sansome St is a 9-story building in Downtown San Francisco with 97% of its floor area within daylight reach of a facade. This screen estimates 68 homes and scores it 91 out of 100 for office-to-residential conversion suitability.
CA-11 · Screened 2026-10-12 · Strong candidate
Also addressed as 501 Washington St and 505 Washington St: San Francisco’s address records place all 3 on this one footprint.
Where 545 Sansome St is
Its block in Downtown San Francisco, drawn from San Francisco's own building outlines and street centerlines.
- Already housing
- Not screened
- 545 Sansome St
This building does not pencil on its own, but a modeled RESIDE Act grant would close the gap if the building qualified for one.
Every floor carries 226 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 8 residential floors that is 1,809 sq ft of cost carrying no revenue.
Modeled conversion metrics for 545 Sansome St, 2026-10-12.
| Suitability scoreStrong candidate | 91 / 100 |
|---|---|
| Storiesfrom 104 ft LiDAR (2010) height ÷ 12 ft floor-to-floor | 9 |
| Floor plateper floor, from the city footprint | 8,296 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 97% |
| Deepest interior pointviability threshold is 80 ft | 41 ft |
| Windowless coreper floor — renovated but never rentable | 226 sq ft |
| Estimated homesat 750 sq ft average | 68 |
| Conversion cost$405/sq ft all-in on 66,366 sq ft | $26.9M |
| Gap before grantshortfall against completed value | $2.0M |
| Modeled RESIDE grantbelow the statutory cap | $4.1M |
| BuiltSan Francisco's own record of the construction year | 1930 |
| ZoningChinatown | C-3-O |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
44 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 377 ft of exterior wall, and across 8 residential floors the building carries 3,017 ft of it in total, divided among the 68 homes this screen estimates.
Its plate is compact at 0.73: 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 8.5 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 545 Sansome St scores 91 out of 100
Daylight efficiency 100, Interior depth 97, Scale 45, Finance 100 — each out of 100, then weighted.
Score components for 545 Sansome St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency97% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 100 | 45% | 45.0 |
| Interior depthdeepest interior point 41 ft from a facade, scored from 80 ft down to 40 ft | 97 | 25% | 24.2 |
| Scale68 estimated homes, scored from 0 up to 150 | 45 | 15% | 6.8 |
| Financecompleted value covers conversion cost with 8% to spare, which tops out the component | 100 | 15% | 15.0 |
Most of what it earns comes from daylight efficiency, and what holds it back most is scale, at 45 out of 100: 68 estimated homes, scored from 0 up to 150.
Built in 1930
San Francisco records this building as going up in 1930, 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 97% daylight figure above deserves.
What the conversion would cost
$405 per square foot all-in across 66,366 sq ft of converted floor, or $26.9M in total — about $395K for each of the 68 homes.
All-in cost per square foot for 545 Sansome 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 1,809 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 68 homes is $24.9M.
What would have to be true
A $2.0M gap before any grant, which the modeled $4.1M closes. What would reopen it soonest: circulation efficiency 7% down.
The shortfall before any grant is $2.0M. Closing it from the value side means each of the 68 homes finishing at $395K rather than the $366K the model assumes — 8% more. Closing it from the cost side means getting all-in cost down from $405 to $375 per square foot.
A modeled RESIDE grant of $4.1M moves that threshold to $335K a home. That is below the assumed value, which is why this building counts as unlocked by the grant — subject to it qualifying under the law's vacant-and-abandoned test, which this data cannot show.
Each of these, moved on its own, would be enough to undo that for 545 Sansome St:
Single-assumption flip points for 545 Sansome St, each holding the other three at their defaults.
| Circulation efficiencythe binding constraint — the least this building would need | 7% downto 74% |
|---|---|
| Average unit size | 8% upto 807 sq ft |
| Completed value per home | 8% downto $335K |
| Conversion cost per square foot | 12% upto $291/sq ft |
All four are sliders in the survey, where 545 Sansome St re-scores against your own numbers.
How it compares in Downtown San Francisco
545 Sansome St ranks 59th of the 205 buildings screened here, against a median score of 87.
Its floor plate is better lit than 64% of them, and shallower than 60% of them at its deepest interior point. On size it is the 151st 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 Chinatown and the C-3-O zone
4th of 12 in Chinatown, 34th of 88 zoned C-3-O — the comparison that shares its rules, rents and streets.
San Francisco places 12 of the screened buildings in Chinatown. 545 Sansome St ranks 4th of them against a median score of 80. 11 score 70 or more, their median deepest interior point is 54 ft from a facade against this building’s 41 ft, and together they would hold an estimated 2,335 homes. The group’s top scorer is 505 Sansome St, at 99.
88 of the screened buildings are zoned C-3-O. 545 Sansome St ranks 34th of them against a median score of 89. 76 score 70 or more, their median deepest interior point is 44 ft from a facade against this building’s 41 ft, and together they would hold an estimated 21,444 homes. The group’s top scorer is 266 Bush St, at 100.
Its nearest match in size: 234 Bush St
The screened building closest to 545 Sansome St in converted floor area is 234 Bush St: 65,744 sq ft over 10 stories, against 66,366 sq ft over 9 here.
The two land within a few points of each other — 91 here, 92 there — so at this size the screen reads them as much the same prospect. On the money they sit in the same place: each pencils only with the modeled RESIDE grant. The two stand about 1,500 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 545 Sansome St $4.1M, 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 545 Sansome St
The 4 closest the screen also covers, from 140 ft away. They are the colored outlines on the plan at the top of this page.
- 505 Sansome St20 stories · 93% daylit · 194 estimated homes · scores 99/100 (Strong candidate)about 140 ft away
- 500 Sansome St8 stories · 81% daylit · 97 estimated homes · scores 72/100 (Strong candidate)about 230 ft away
- 475 Sansome St20 stories · 76% daylit · 336 estimated homes · scores 74/100 (Strong candidate)about 320 ft away
- 450 Sansome St16 stories · 93% daylit · 133 estimated homes · scores 94/100 (Strong candidate)about 370 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.