431 Natoma St
431 Natoma St is a 25-story building in Downtown San Francisco with 100% of its floor area within daylight reach of a facade. This screen estimates 193 homes and scores it 100 out of 100 for office-to-residential conversion suitability.
CA-11 · Screened 2026-10-12 · Strong candidate
No address point in San Francisco’s records falls inside this footprint, so it is named by the closest one that no other screened building claims — usually a site entrance, but check the outline on the plan below before relying on the street number.
Where 431 Natoma St is
Its block in Downtown San Francisco, drawn from San Francisco's own building outlines and street centerlines.
- Already housing
- Not screened
- 431 Natoma 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.
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.
Height not confirmed. The city's 2010 LiDAR survey measures this building at 35 ft, which does not fit the 25 floors on the 2025 Assessor roll. The building may have been built or altered since 2010. The model uses the Assessor's floor count and draws the building 300 ft tall from it.
Modeled conversion metrics for 431 Natoma St, 2026-10-12.
| Suitability scoreStrong candidate | 100 / 100 |
|---|---|
| Storiesfrom 300 ft LiDAR (2010) height ÷ 12 ft floor-to-floor | 25 |
| Floor plateper floor, from the city footprint | 7,563 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 100% |
| Deepest interior pointviability threshold is 80 ft | 23 ft |
| Windowless coreper floor — renovated but never rentable | 0 sq ft |
| Estimated homesat 750 sq ft average | 193 |
| Conversion cost$405/sq ft all-in on 181,513 sq ft | $73.5M |
| Gap before grantshortfall against completed value | $2.9M |
| Modeled RESIDE grantat the statutory per-award cap | $10.0M |
| BuiltSan Francisco's own record of the construction year | 2022 |
| ZoningSouth of Market | C-3-S |
| 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 415 ft of exterior wall, and across 24 residential floors the building carries 9,955 ft of it in total, divided among the 193 homes this screen estimates.
Its plate is moderately compact at 0.55: 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 8.0 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 431 Natoma St scores 100 out of 100
Daylight efficiency 100, Interior depth 100, Scale 100, Finance 100 — each out of 100, then weighted.
Score components for 431 Natoma 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 23 ft from a facade, scored from 80 ft down to 40 ft | 100 | 25% | 25.0 |
| Scale193 estimated homes, scored from 0 up to 150 | 100 | 15% | 15.0 |
| Financecompleted value covers conversion cost with 10% to spare, which tops out the component | 100 | 15% | 15.0 |
Every component scores at or near full marks, so nothing in the geometry or the pro-forma is holding this one back — daylight efficiency carries the most weight of the four.
Built in 2022
San Francisco records this building as going up in 2022, which puts it in the modern stock.
As a rule, newer systems and better structure, but usually built deep and sealed for office use, and rarely cheap enough to buy at a price that lets a conversion pencil. 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
$405 per square foot all-in across 181,513 sq ft of converted floor, or $73.5M in total — about $381K for each of the 193 homes.
All-in cost per square foot for 431 Natoma 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 circulation and service area that earns nothing directly. Against it the model sets a completed value of $366K a home, which for 193 homes is $70.6M.
What would have to be true
A $2.9M gap before any grant, which the modeled $10.0M closes. What would reopen it soonest: completed value per home 10% down.
The shortfall before any grant is $2.9M. Closing it from the value side means each of the 193 homes finishing at $381K rather than the $366K the model assumes — 4% more. Closing it from the cost side means getting all-in cost down from $405 to $389 per square foot.
A modeled RESIDE grant of $10.0M moves that threshold to $329K 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 431 Natoma St:
Single-assumption flip points for 431 Natoma St, each holding the other three at their defaults.
| Completed value per homethe binding constraint — the least this building would need | 10% downto $329K |
|---|---|
| Circulation efficiency | 10% downto 72% |
| Average unit size | 11% upto 835 sq ft |
| Conversion cost per square foot | 15% upto $299/sq ft |
All four are sliders in the survey, where 431 Natoma St re-scores against your own numbers.
How it compares in Downtown San Francisco
431 Natoma St ranks 1st of the 205 buildings screened here, against a median score of 87.
Its floor plate is better lit than 100% of them, and shallower than 97% of them at its deepest interior point. On size it is the 89th 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 South of Market and the C-3-S zone
1st of 14 in South of Market, 1st of 4 zoned C-3-S — the comparison that shares its rules, rents and streets.
San Francisco places 14 of the screened buildings in South of Market. 431 Natoma St ranks 1st of them against a median score of 82, the top score in the group. 9 score 70 or more, their median deepest interior point is 45 ft from a facade against this building’s 23 ft, and together they would hold an estimated 2,045 homes.
4 of the screened buildings are zoned C-3-S. 431 Natoma St ranks 1st of them against a median score of 72, the top score in the group. 2 score 70 or more, their median deepest interior point is 53 ft from a facade against this building’s 23 ft, and together they would hold an estimated 651 homes.
Its nearest match in size: 401 California St
The screened building closest to 431 Natoma St in converted floor area is 401 California St: 175,072 sq ft over 26 stories, against 181,513 sq ft over 25 here.
The two land within a few points of each other — 100 here, 100 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 4,400 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 431 Natoma 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 431 Natoma St
The 4 closest the screen also covers, from 480 ft away. They are the colored outlines on the plan at the top of this page.
- 959 Mission St7 stories · 100% daylit · 70 estimated homes · scores 92/100 (Strong candidate)about 480 ft away
- 155 5th St7 stories · 51% daylit · 167 estimated homes · scores 29/100 (Unlikely)about 480 ft away
- 479 Jessie St4 stories · 100% daylit · 26 estimated homes · scores 88/100 (Strong candidate)about 760 ft away
- 901 Market St5 stories · 64% daylit · 83 estimated homes · scores 35/100 (Marginal)about 1,030 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.