300 S 1st St
300 S 1st St is a 7-story building in Downtown San Jose with 75% of its floor area within daylight reach of a facade. This screen estimates 101 homes and scores it 62 out of 100 for office-to-residential conversion suitability.
CA-18 · Screened 2026-09-12 · Worth a feasibility study
Also addressed as 310 S 1st St and 322 S 1st St: San Jose’s address records place all 3 on this one footprint.
Where 300 S 1st St is
Its block in Downtown San Jose, drawn from San Jose's own building outlines and street centerlines.
- Already housing
- Not screened
- 300 S 1st St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Every floor carries 5,215 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 6 residential floors that is 31,292 sq ft of cost carrying no revenue.
Modeled conversion metrics for 300 S 1st St, 2026-09-12.
| Suitability scoreWorth a feasibility study | 62 / 100 |
|---|---|
| Storiesfrom 85 ft LiDAR height ÷ 12 ft floor-to-floor | 7 |
| Floor plateper floor, from the city footprint | 21,031 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 75% |
| Deepest interior pointviability threshold is 80 ft | 70 ft |
| Windowless coreper floor — renovated but never rentable | 5,215 sq ft |
| Estimated homesat 750 sq ft average | 101 |
| Conversion cost$405/sq ft all-in on 126,186 sq ft | $51.1M |
| Gap before grantshortfall against completed value | $8.2M |
| Modeled RESIDE grantbelow the statutory cap | $6.1M |
| BuiltSan Jose does not publish a construction year with this data | — |
| ZoningDowntown San Jose | DC |
| Opportunity Zonecensus tract 06085500901, 2018 designation | Yes |
The plan: window line, shape and floor rhythm
37 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 625 ft of exterior wall, and across 6 residential floors the building carries 3,747 ft of it in total, divided among the 101 homes this screen estimates.
Its plate is moderately compact at 0.68: 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 16.8 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 300 S 1st St scores 62 out of 100
Daylight efficiency 70, Interior depth 25, Scale 67, Finance 93 — each out of 100, then weighted.
Score components for 300 S 1st St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency75% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 70 | 45% | 31.7 |
| Interior depthdeepest interior point 70 ft from a facade, scored from 80 ft down to 40 ft | 25 | 25% | 6.2 |
| Scale101 estimated homes, scored from 0 up to 150 | 67 | 15% | 10.1 |
| Financeremaining gap is 4% of conversion cost, scored from 60% down to 0% | 93 | 15% | 14.0 |
Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 25 out of 100: deepest interior point 70 ft from a facade, scored from 80 ft down to 40 ft.
What the conversion would cost
$405 per square foot all-in across 126,186 sq ft of converted floor, or $51.1M in total — about $506K for each of the 101 homes.
All-in cost per square foot for 300 S 1st 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 31,292 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 101 homes is $42.9M.
What would have to be true
A $8.2M gap before any grant, $2.1M after the modeled one. The smallest single change that would close it: average unit size 5% down.
The shortfall before any grant is $8.2M. Closing it from the value side means each of the 101 homes finishing at $506K rather than the $425K the model assumes — 19% more. Closing it from the cost side means getting all-in cost down from $405 to $340 per square foot.
A modeled RESIDE grant of $6.1M moves that threshold to $446K a home. That is still above the $425K assumed, leaving $2.1M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 300 S 1st St, one alone would close the gap at:
Single-assumption flip points for 300 S 1st St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 5% downto 716 sq ft |
|---|---|
| Circulation efficiency | 5% upto 84% |
| Completed value per home | 5% upto $446K |
| Conversion cost per square foot | 6% downto $243/sq ft |
All four are sliders in the survey, where 300 S 1st St re-scores against your own numbers.
How it compares in Downtown San Jose
300 S 1st St ranks 42nd of the 82 buildings screened here, against a median score of 64.
Its floor plate is better lit than 51% of them, and shallower than 43% of them at its deepest interior point. On size it is the 71st 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
36th of 72 zoned DC — the comparison that shares its rules, rents and streets.
72 of the screened buildings are zoned DC. 300 S 1st St ranks 36th 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 70 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: 201 Bassett St
The screened building closest to 300 S 1st St in converted floor area is 201 Bassett St: 125,849 sq ft over 6 stories, against 126,186 sq ft over 7 here.
300 S 1st St scores 62 to its 76, and with the size held roughly equal most of that shortfall comes from interior depth: 25 out of 100 here, 69 there (deepest interior point 52 ft from a facade, scored from 80 ft down to 40 ft). On the money they sit in the same place: each falls short even with the modeled grant. The two stand about 4,700 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 300 S 1st St $6.1M, 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 06085500901, a 2018 designated Opportunity Zone, which Section 201 lets HUD favor — one of the few statutory priorities this screen can actually check.
Other buildings screened near 300 S 1st St
The 4 closest the screen also covers, from 310 ft away. They are the colored outlines on the plan at the top of this page.
- 94 E San Carlos St8 stories · 52% daylit · 261 estimated homes · scores 31/100 (Marginal)about 310 ft away
- 301 S 1st St22 stories · 45% daylit · 1,549 estimated homes · scores 23/100 (Unlikely)about 340 ft away
- 88 E San Carlos St17 stories · 49% daylit · already an apartment buildingabout 420 ft away
- 200 S Market St5 stories · 79% daylit · 57 estimated homes · scores 69/100 (Worth a feasibility study)about 490 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.