127 Post St

127 Post St is a 20-story building in Downtown San Jose with 62% of its floor area within daylight reach of a facade. This screen estimates 687 homes and scores it 35 out of 100 for office-to-residential conversion suitability.

CA-18 · Screened 2026-09-12 · Marginal

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Also addressed as 1 S Market St, 35 S Market St and 142 W Santa Clara St: San Jose’s address records place all 4 on this one footprint.

Where 127 Post St is

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

Suitability score

0–29

30–49

50–69

70–100

Already housing
Not screened
127 Post St

127 Post St and the 1,000 ft of Downtown San Jose around it. The streets are drawn at the width of the right-of-way they run down, sidewalks included, and named, and every building on these blocks is drawn. What is left open and stippled is neither: a surface lot, a plaza or a vacant parcel. The screened buildings are colored by the ramp above, the same one the district map uses, carry their score, and each is a link to its own page. Each casts a shadow as long as its measured height lets it, so towers stand out from the low buildings around them; the unscreened buildings have no measured height and cast none. 127 Post St is outlined in its own score color at the outline it covers at ground level. Its windowless core is hatched. The inset places it among every building the screen covers.

Floor plan: 62% of each floor sits within daylight reach of a facade. The shading is daylight, darkest at the windows and gone 35 ft in. The hatched area is windowless core: 20,362 sq ft per floor that must be renovated but can never be rented as an apartment. The dimension marks the deepest interior point, 96 ft from the nearest window. A–A is where the section beside it is cut.

Section A–A: cut across the depth of the plate, through the middle of the core. Daylight reaches 35 ft in from every facade, fading as it goes, and the hatched stripe left between the lit edges is floor that gets converted and can never be rented: 20,362 sq ft on the floor the screen scores, and 386,883 sq ft over 19 residential floors. The shaded ground floor is converted like the rest and counted as no homes.

This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.

Every floor carries 20,362 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 19 residential floors that is 386,883 sq ft of cost carrying no revenue.

Part of this building is already homes. San Jose's rental housing and condominium records list 320 apartments here, fewer than half the homes this model estimates the building could hold. The figures here treat the whole building as convertible, so read them as an upper bound and check which floors are already housing.

Read with caution. This footprint carries 4 street addresses across 54,288 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 127 Post St, 2026-09-12.

Suitability scoreMarginal	35 / 100
Storiesfrom 242 ft LiDAR height ÷ 12 ft floor-to-floor	20
Floor plateper floor, from the city footprint	54,288 sq ft
Daylight efficiencyshare within 35 ft of a facade	62%
Deepest interior pointviability threshold is 80 ft	96 ft
Windowless coreper floor — renovated but never rentable	20,362 sq ft
Estimated homesat 750 sq ft average	687
Conversion cost$405/sq ft all-in on 1,031,474 sq ft	$417.7M
Gap before grantshortfall against completed value	$125.8M
Modeled RESIDE grantat the statutory per-award cap	$10.0M
BuiltSan Jose does not publish a construction year with this data	—
ZoningDowntown San Jose	DC
Opportunity Zonecensus tract 06085500800, 2018 designation	Yes

The plan: window line, shape and floor rhythm

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

The typical floor has 1,236 ft of exterior wall, and across 19 residential floors the building carries 23,475 ft of it in total, divided among the 687 homes this screen estimates.

Its plate is elongated at 0.45: 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 36.2 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 127 Post St scores 35 out of 100

The weighted components add to 43, but the score is capped at 35 because its deepest interior point is 96 ft from a facade, past the 80 ft threshold beyond which conversion requires carving a light well.

Score components for 127 Post St. Points are the subscore times its weight.

Component	Subscore	Weight	Points
Daylight efficiency62% of the floor area within 35 ft of a facade, scored from 40% up to 90%	45	45%	20.2
Interior depthdeepest interior point 96 ft from a facade, scored from 80 ft down to 40 ft	0	25%	0.0
Scale687 estimated homes, scored from 0 up to 150	100	15%	15.0
Financeremaining gap is 28% of conversion cost, scored from 60% down to 0%	54	15%	8.1

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 96 ft from a facade, scored from 80 ft down to 40 ft.

What the conversion would cost

$405 per square foot all-in across 1,031,474 sq ft of converted floor, or $417.7M in total — about $608K for each of the 687 homes.

All-in cost per square foot for 127 Post 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 386,883 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 $425K a home, which for 687 homes is $292.0M.

What would have to be true

A $125.8M gap before any grant, $115.8M after the modeled one. The smallest single change that would close it: average unit size 28% down.

The shortfall before any grant is $125.8M. Closing it from the value side means each of the 687 homes finishing at $608K rather than the $425K the model assumes — 43% more. Closing it from the cost side means getting all-in cost down from $405 to $283 per square foot.

A modeled RESIDE grant of $10.0M moves that threshold to $594K a home. That is still above the $425K assumed, leaving $115.8M uncovered, which is why the grant does not unlock this one.

Nor do all four levers have to move. For 127 Post St, one alone would close the gap at:

Single-assumption flip points for 127 Post St, each holding the other three at their defaults.

Average unit sizethe binding constraint — the least this building would need	28% downto 537 sq ft
Completed value per home	40% upto $594K
Conversion cost per square foot	43% downto $148/sq ft

All four are sliders in the survey, where 127 Post St re-scores against your own numbers.

How it compares in Downtown San Jose

127 Post St ranks 59th of the 82 buildings screened here, against a median score of 64.

Its floor plate is better lit than 32% of them, and shallower than 20% of them at its deepest interior point. On size it is the 10th largest by estimated homes. The full survey of all 82 buildings ranks and maps every one of them, and the list by address links each to its own page.

Within the DC zone

50th of 72 zoned DC — the comparison that shares its rules, rents and streets.

72 of the screened buildings are zoned DC. 127 Post St ranks 50th of them against a median score of 61. 31 score 70 or more, their median deepest interior point is 68 ft from a facade against this building’s 96 ft, and together they would hold an estimated 23,276 homes. The group’s top scorer is 1 Almaden Blvd, at 100.

Its nearest match in size: 10 Almaden Blvd

The screened building closest to 127 Post St in converted floor area is 10 Almaden Blvd: 1,150,248 sq ft over 18 stories, against 1,031,474 sq ft over 20 here.

127 Post St scores 35 to its 25, and with the size held roughly equal most of that lead comes from daylight efficiency: 45 out of 100 here, 14 there (47% of the floor area within 35 ft of a facade, scored from 40% up to 90%). On the money they sit in the same place: each falls short even with the modeled grant. The two stand about 600 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 127 Post 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.

This building does sit in census tract 06085500800, a 2018 designated Opportunity Zone, which Section 201 lets HUD favor — one of the few statutory priorities this screen can actually check.