240 Montgomery St
240 Montgomery St is a 17-story building in Downtown San Francisco with 99% of its floor area within daylight reach of a facade. This screen estimates 138 homes and scores it 99 out of 100 for office-to-residential conversion suitability.
CA-11 · Screened 2026-10-12 · Strong candidate
Also addressed as 250 Montgomery St: San Francisco’s address records place both on this one footprint.
Where 240 Montgomery St is
Its block in Downtown San Francisco, drawn from San Francisco's own building outlines and street centerlines.
- Already housing
- Not screened
- 240 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 105 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 16 residential floors that is 1,684 sq ft of cost carrying no revenue.
Modeled conversion metrics for 240 Montgomery St, 2026-10-12.
| Suitability scoreStrong candidate | 99 / 100 |
|---|---|
| Storiesfrom 223 ft LiDAR (2010) height ÷ 12 ft floor-to-floor | 17 |
| Floor plateper floor, from the city footprint | 8,248 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 99% |
| Deepest interior pointviability threshold is 80 ft | 36 ft |
| Windowless coreper floor — renovated but never rentable | 105 sq ft |
| Estimated homesat 750 sq ft average | 138 |
| Conversion cost$405/sq ft all-in on 131,965 sq ft | $53.4M |
| Gap before grantshortfall against completed value | $2.9M |
| Modeled RESIDE grantbelow the statutory cap | $8.3M |
| BuiltSan Francisco's own record of the construction year | 1986 |
| ZoningFinancial District/South Beach | C-3-O |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
45 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 384 ft of exterior wall, and across 16 residential floors the building carries 6,143 ft of it in total, divided among the 138 homes this screen estimates.
Its plate is moderately compact at 0.70: 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 8.6 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 240 Montgomery St scores 99 out of 100
Daylight efficiency 100, Interior depth 100, Scale 92, Finance 100 — each out of 100, then weighted.
Score components for 240 Montgomery St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency99% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 100 | 45% | 45.0 |
| Interior depthdeepest interior point 36 ft from a facade, scored from 80 ft down to 40 ft | 100 | 25% | 25.0 |
| Scale138 estimated homes, scored from 0 up to 150 | 92 | 15% | 13.8 |
| Financecompleted value covers conversion cost with 10% 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 92 out of 100: 138 estimated homes, scored from 0 up to 150.
Built in 1986
San Francisco records this building as going up in 1986, 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 99% daylight figure above deserves.
What the conversion would cost
$405 per square foot all-in across 131,965 sq ft of converted floor, or $53.4M in total — about $387K for each of the 138 homes.
All-in cost per square foot for 240 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 1,684 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 138 homes is $50.5M.
What would have to be true
A $2.9M gap before any grant, which the modeled $8.3M closes. What would reopen it soonest: circulation efficiency 9% down.
The shortfall before any grant is $2.9M. Closing it from the value side means each of the 138 homes finishing at $387K rather than the $366K the model assumes — 6% more. Closing it from the cost side means getting all-in cost down from $405 to $383 per square foot.
A modeled RESIDE grant of $8.3M moves that threshold to $327K 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 240 Montgomery St:
Single-assumption flip points for 240 Montgomery St, each holding the other three at their defaults.
| Circulation efficiencythe binding constraint — the least this building would need | 9% downto 73% |
|---|---|
| Average unit size | 10% upto 827 sq ft |
| Completed value per home | 11% downto $327K |
| Conversion cost per square foot | 16% upto $300/sq ft |
All four are sliders in the survey, where 240 Montgomery St re-scores against your own numbers.
How it compares in Downtown San Francisco
240 Montgomery St ranks 27th of the 205 buildings screened here, against a median score of 87.
Its floor plate is better lit than 67% of them, and shallower than 70% of them at its deepest interior point. On size it is the 111th 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 zone
25th of 165 in Financial District/South Beach, 20th of 88 zoned C-3-O — the comparison that shares its rules, rents and streets.
San Francisco places 165 of the screened buildings in Financial District/South Beach. 240 Montgomery St ranks 25th 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 36 ft, and together they would hold an estimated 40,456 homes. The group’s top scorer is 870 Market St, at 100.
88 of the screened buildings are zoned C-3-O. 240 Montgomery St ranks 20th 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 36 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: 785 Market St
The screened building closest to 240 Montgomery St in converted floor area is 785 Market St: 133,962 sq ft over 18 stories, against 131,965 sq ft over 17 here.
The two land within a few points of each other — 99 here, 99 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 2,300 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 240 Montgomery St $8.3M, 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 240 Montgomery St
The 4 closest the screen also covers, from 90 ft away. They are the colored outlines on the plan at the top of this page.
- 369 Pine St8 stories · 100% daylit · 56 estimated homes · scores 91/100 (Strong candidate)about 90 ft away
- 266 Bush St10 stories · 100% daylit · 246 estimated homes · scores 100/100 (Strong candidate)about 160 ft away
- 475 California St12 stories · 93% daylit · 261 estimated homes · scores 94/100 (Strong candidate)about 240 ft away
- 234 Bush St10 stories · 100% daylit · 70 estimated homes · scores 92/100 (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.