1640 Mission St
1640 Mission St is a 5-story building in Downtown San Francisco with 59% of its floor area within daylight reach of a facade. This screen estimates 110 homes and scores it 34 out of 100 for office-to-residential conversion suitability.
CA-11 · Screened 2026-10-12 · Marginal
Also addressed as 1650 Mission St, 1656 Mission St and 77 Otis St: San Francisco’s address records place all 4 on this one footprint.
Where 1640 Mission St is
Its block in Downtown San Francisco, drawn from San Francisco's own building outlines and street centerlines.
- Already housing
- Not screened
- 1640 Mission St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Every floor carries 18,239 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 4 residential floors that is 72,957 sq ft of cost carrying no revenue.
Read with caution. This footprint carries 4 street addresses across 44,055 sq ft, which usually means the city’s GIS has merged a block or complex into a single polygon rather than describing one convertible building.
Modeled conversion metrics for 1640 Mission St, 2026-10-12.
| Suitability scoreMarginal | 34 / 100 |
|---|---|
| Storiesfrom 72 ft LiDAR (2010) height ÷ 12 ft floor-to-floor | 5 |
| Floor plateper floor, from the city footprint | 44,055 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 59% |
| Deepest interior pointviability threshold is 80 ft | 88 ft |
| Windowless coreper floor — renovated but never rentable | 18,239 sq ft |
| Estimated homesat 750 sq ft average | 110 |
| Conversion cost$405/sq ft all-in on 176,220 sq ft | $71.4M |
| Gap before grantshortfall against completed value | $31.1M |
| Modeled RESIDE grantbelow the statutory cap | $6.6M |
| BuiltSan Francisco's own record of the construction year | 1962 |
| ZoningMission | C-3-G |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
32 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 872 ft of exterior wall, and across 4 residential floors the building carries 3,488 ft of it in total, divided among the 110 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 27.5 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 1640 Mission St scores 34 out of 100
Daylight efficiency 37, Interior depth 0, Scale 73, Finance 43 — each out of 100, then weighted.
Score components for 1640 Mission St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency59% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 37 | 45% | 16.7 |
| Interior depthdeepest interior point 88 ft from a facade, scored from 80 ft down to 40 ft | 0 | 25% | 0.0 |
| Scale110 estimated homes, scored from 0 up to 150 | 73 | 15% | 11.0 |
| Financeremaining gap is 34% of conversion cost, scored from 60% down to 0% | 43 | 15% | 6.4 |
Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 0 out of 100: deepest interior point 88 ft from a facade, scored from 80 ft down to 40 ft.
Built in 1962
San Francisco records this building as going up in 1962, which puts it in the post-war stock.
As a rule, the period when plates got deep and facades became curtain wall: sealed glazing, lower floor-to-floor heights, and mechanical systems designed around a sealed box. Conversions here usually turn on whether the windows can be made to open and whether ceilings survive new plumbing. 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 59% daylight figure above deserves.
What the conversion would cost
$405 per square foot all-in across 176,220 sq ft of converted floor, or $71.4M in total — about $649K for each of the 110 homes.
All-in cost per square foot for 1640 Mission 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 72,957 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 110 homes is $40.3M.
What would have to be true
A $31.1M gap before any grant, $24.5M after the modeled one. The smallest single change that would close it: average unit size 34% down.
The shortfall before any grant is $31.1M. Closing it from the value side means each of the 110 homes finishing at $649K rather than the $366K the model assumes — 77% more. Closing it from the cost side means getting all-in cost down from $405 to $228 per square foot.
A modeled RESIDE grant of $6.6M moves that threshold to $589K a home. That is still above the $366K assumed, leaving $24.5M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 1640 Mission St, one alone would close the gap at:
Single-assumption flip points for 1640 Mission St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 34% downto 492 sq ft |
|---|---|
| Conversion cost per square foot | 53% downto $121/sq ft |
| Completed value per home | 61% upto $589K |
All four are sliders in the survey, where 1640 Mission St re-scores against your own numbers.
How it compares in Downtown San Francisco
1640 Mission St ranks 202nd of the 205 buildings screened here, against a median score of 87.
Its floor plate is better lit than 2% of them, and shallower than 2% of them at its deepest interior point. On size it is the 123rd 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 Mission and the C-3-G zone
3rd of 4 in Mission, 21st of 22 zoned C-3-G — the comparison that shares its rules, rents and streets.
San Francisco places 4 of the screened buildings in Mission. 1640 Mission St ranks 3rd of them against a median score of 58. 2 score 70 or more, their median deepest interior point is 69 ft from a facade against this building’s 88 ft, and together they would hold an estimated 455 homes. The group’s top scorer is 1660 Mission St, at 83.
22 of the screened buildings are zoned C-3-G. 1640 Mission St ranks 21st of them against a median score of 76. 13 score 70 or more, their median deepest interior point is 51 ft from a facade against this building’s 88 ft, and together they would hold an estimated 2,588 homes. The group’s top scorer is 40 Leavenworth St, at 92.
Its nearest match in size: 20 Annie St
The screened building closest to 1640 Mission St in converted floor area is 20 Annie St: 174,013 sq ft over 10 stories, against 176,220 sq ft over 5 here.
20 Annie St scores 100 and 1640 Mission St only 34, and the difference is a hard fail rather than a matter of degree: the lower one is capped at 35 because its deepest interior point is 88 ft from a facade, past the 80 ft threshold beyond which conversion requires carving a light well. On the money they part ways: 20 Annie St pencils only with the modeled RESIDE grant, while 1640 Mission St falls short even with the modeled grant. The two stand about 7,600 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 1640 Mission St $6.6M, 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 1640 Mission St
The 4 closest the screen also covers, from 190 ft away. They are the colored outlines on the plan at the top of this page.
- 1660 Mission St6 stories · 88% daylit · 67 estimated homes · scores 83/100 (Strong candidate)about 190 ft away
- 1563 Mission St5 stories · 90% daylit · 40 estimated homes · scores 82/100 (Strong candidate)about 660 ft away
- 1525 Market St8 stories · 49% daylit · 238 estimated homes · scores 27/100 (Unlikely)about 1,170 ft away
- 25 Hickory St8 stories · 75% daylit · 115 estimated homes · scores 65/100 (Worth a feasibility study)about 1,400 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.