870 Market St

Where 870 Market St is

Its block in Downtown San Francisco, drawn from San Francisco's own building outlines and street centerlines.

The plan: window line, shape and floor rhythm

39 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.

The typical floor has 1,149 ft of exterior wall, and across 11 residential floors the building carries 12,641 ft of it in total, divided among the 324 homes this screen estimates.

Its plate is elongated at 0.26: a slab or an L, which is why so much of the floor lies within reach of a window: the outline buys daylight that a square plan of the same area would not. How window line and plate shape are measured.

At the model’s 750 sq ft average, the plan works out at about 29.5 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 870 Market St scores 100 out of 100

Daylight efficiency 100, Interior depth 100, Scale 100, Finance 100 — each out of 100, then weighted.

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 1907

San Francisco records this building as going up in 1907, which puts it in the pre-1920 stock.

As a rule, the era that converts most readily: load-bearing masonry, small floor plates laid out before deep-plan offices were possible, operable windows and generous floor-to-floor heights. The usual obstacles are not daylight but hazardous materials, lifts and bringing structure up to current code. 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 304,071 sq ft of converted floor, or $123.1M in total — about $380K for each of the 324 homes.

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 324 homes is $118.6M.

What would have to be true

A $4.6M gap before any grant, which the modeled $10.0M closes. What would reopen it soonest: circulation efficiency 4% down.

The shortfall before any grant is $4.6M. Closing it from the value side means each of the 324 homes finishing at $380K rather than the $366K the model assumes — 4% more. Closing it from the cost side means getting all-in cost down from $405 to $390 per square foot.

A modeled RESIDE grant of $10.0M moves that threshold to $349K 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 870 Market St:

All four are sliders in the survey, where 870 Market St re-scores against your own numbers.

How it compares in Downtown San Francisco

870 Market 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 76% of them at its deepest interior point. On size it is the 49th 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-R zone

1st of 165 in Financial District/South Beach, 1st of 25 zoned C-3-R — the comparison that shares its rules, rents and streets.

San Francisco places 165 of the screened buildings in Financial District/South Beach. 870 Market St ranks 1st of them against a median score of 88, the top score in the group. 121 score 70 or more, their median deepest interior point is 47 ft from a facade against this building’s 32 ft, and together they would hold an estimated 40,456 homes.

25 of the screened buildings are zoned C-3-R. 870 Market St ranks 1st of them against a median score of 90, the top score in the group. 21 score 70 or more, their median deepest interior point is 32 ft from a facade against this building’s 32 ft, and together they would hold an estimated 2,773 homes.

Its nearest match in size: 201 3rd St

The screened building closest to 870 Market St in converted floor area is 201 3rd St: 310,038 sq ft over 12 stories, against 304,071 sq ft over 12 here.

870 Market St scores 100 to its 52, and with the size held roughly equal most of that lead comes from daylight efficiency: 100 out of 100 here, 54 there (67% of the floor area within 35 ft of a facade, scored from 40% up to 90%). On the money they part ways: 201 3rd St falls short even with the modeled grant, while 870 Market St pencils only with the modeled RESIDE grant. The two stand about 2,200 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 870 Market 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 870 Market St

The 4 closest the screen also covers, from 520 ft away. They are the colored outlines on the plan at the top of this page.

• 25 Cyril Magnin St
  8 stories · 100% daylit · 66 estimated homes · scores 92/100 (Strong candidate)
  about 520 ft away
• 901 Market St
  5 stories · 64% daylit · 83 estimated homes · scores 35/100 (Marginal)
  about 620 ft away
• 750 Market St
  11 stories · 72% daylit · 383 estimated homes · scores 57/100 (Worth a feasibility study)
  about 680 ft away
• 785 Market St
  18 stories · 100% daylit · 142 estimated homes · scores 99/100 (Strong candidate)
  about 710 ft away