90 New Montgomery St
90 New Montgomery St is a 15-story building in Downtown San Francisco with 96% of its floor area within daylight reach of a facade. This screen estimates 127 homes and scores it 98 out of 100 for office-to-residential conversion suitability.
CA-11 · Screened 2026-10-12 · Strong candidate
Where 90 New Montgomery St is
Its block in Downtown San Francisco, drawn from San Francisco's own building outlines and street centerlines.
- Already housing
- Not screened
- 90 New Montgomery 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 354 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 14 residential floors that is 4,958 sq ft of cost carrying no revenue.
Modeled conversion metrics for 90 New Montgomery St, 2026-10-12.
| Suitability scoreStrong candidate | 98 / 100 |
|---|---|
| Storiesfrom 213 ft LiDAR (2010) height ÷ 12 ft floor-to-floor | 15 |
| Floor plateper floor, from the city footprint | 8,913 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 96% |
| Deepest interior pointviability threshold is 80 ft | 39 ft |
| Windowless coreper floor — renovated but never rentable | 354 sq ft |
| Estimated homesat 750 sq ft average | 127 |
| Conversion cost$405/sq ft all-in on 124,783 sq ft | $50.5M |
| Gap before grantshortfall against completed value | $4.1M |
| Modeled RESIDE grantbelow the statutory cap | $7.6M |
| 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
42 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 385 ft of exterior wall, and across 14 residential floors the building carries 5,385 ft of it in total, divided among the 127 homes this screen estimates.
Its plate is compact at 0.76: 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 9.1 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 90 New Montgomery St scores 98 out of 100
Daylight efficiency 100, Interior depth 100, Scale 85, Finance 100 — each out of 100, then weighted.
Score components for 90 New Montgomery St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency96% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 100 | 45% | 45.0 |
| Interior depthdeepest interior point 39 ft from a facade, scored from 80 ft down to 40 ft | 100 | 25% | 25.0 |
| Scale127 estimated homes, scored from 0 up to 150 | 85 | 15% | 12.7 |
| Financecompleted value covers conversion cost with 7% 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 85 out of 100: 127 estimated homes, scored from 0 up to 150.
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 96% daylight figure above deserves.
What the conversion would cost
$405 per square foot all-in across 124,783 sq ft of converted floor, or $50.5M in total — about $398K for each of the 127 homes.
All-in cost per square foot for 90 New Montgomery 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 4,958 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 127 homes is $46.5M.
What would have to be true
A $4.1M gap before any grant, which the modeled $7.6M closes. What would reopen it soonest: circulation efficiency 7% down.
The shortfall before any grant is $4.1M. Closing it from the value side means each of the 127 homes finishing at $398K rather than the $366K the model assumes — 9% more. Closing it from the cost side means getting all-in cost down from $405 to $373 per square foot.
A modeled RESIDE grant of $7.6M moves that threshold to $338K 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 90 New Montgomery St:
Single-assumption flip points for 90 New Montgomery 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 | 7% upto 806 sq ft |
| Completed value per home | 8% downto $338K |
| Conversion cost per square foot | 11% upto $289/sq ft |
All four are sliders in the survey, where 90 New Montgomery St re-scores against your own numbers.
How it compares in Downtown San Francisco
90 New Montgomery St ranks 30th of the 205 buildings screened here, against a median score of 87.
Its floor plate is better lit than 61% of them, and shallower than 65% of them at its deepest interior point. On size it is the 116th 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
28th of 165 in Financial District/South Beach, 6th 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. 90 New Montgomery St ranks 28th 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 39 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). 90 New Montgomery St ranks 6th 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 39 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: 450 Sansome St
The screened building closest to 90 New Montgomery St in converted floor area is 450 Sansome St: 134,407 sq ft over 16 stories, against 124,783 sq ft over 15 here.
90 New Montgomery St scores 98 to its 94, and with the size held roughly equal most of that lead comes from interior depth: 100 out of 100 here, 84 there (deepest interior point 46 ft from a facade, scored from 80 ft down to 40 ft). On the money they sit in the same place: each pencils only with the modeled RESIDE grant. The two stand about 2,600 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 90 New Montgomery St $7.6M, 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 90 New Montgomery 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.
- 138 Minna St9 stories · 99% daylit · 133 estimated homes · scores 98/100 (Strong candidate)about 200 ft away
- 647 Mission St5 stories · 100% daylit · 26 estimated homes · scores 88/100 (Strong candidate)about 220 ft away
- 617 Mission St6 stories · 96% daylit · 62 estimated homes · scores 90/100 (Strong candidate)about 260 ft away
- 150 Minna St6 stories · 88% daylit · 67 estimated homes · scores 86/100 (Strong candidate)about 260 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.