1621 18th St
1621 18th St is a 6-story building in Greater Downtown Denver with 73% of its floor area within daylight reach of a facade. This screen estimates 88 homes and scores it 60 out of 100 for office-to-residential conversion suitability.
CO-1 · Screened 2026-09-19 · Worth a feasibility study
Where 1621 18th St is
Its block in Greater Downtown Denver, drawn from Denver's own building outlines and street centerlines.
- Already housing
- Not screened
- 1621 18th St
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Across its 5 residential floors this building carries 30,620 sq ft of windowless core — area that must be gutted, re-plumbed and sprinklered but can never be rented as an apartment.
Modeled conversion metrics for 1621 18th St, 2026-09-19.
| Suitability scoreWorth a feasibility study | 60 / 100 |
|---|---|
| Storiesfrom 69 ft aerial-survey height ÷ 12 ft floor-to-floor | 6 |
| Height bandsfloor plate by floor range, from the city's roof outlines | Floors 1–5: 28,345 sq ft · Floor 6: 415 sq ft |
| Floor platetypical floor, from the city outlines | 28,345 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 73% |
| Deepest interior pointviability threshold is 80 ft | 56 ft |
| Windowless coretypical floor; the building-wide total is in the text above | 7,655 sq ft |
| Estimated homesat 750 sq ft average | 88 |
| Conversion cost$360/sq ft all-in on 113,796 sq ft | $41.0M |
| Gap before grantshortfall against completed value | $20.2M |
| Modeled RESIDE grantbelow the statutory cap | $5.3M |
| BuiltDenver does not publish a construction year with this data | — |
| ZoningUnion Station | D-LD |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
35 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 739 ft of exterior wall, and across 5 residential floors the building carries 3,044 ft of it in total, divided among the 88 homes this screen estimates.
Its plate is moderately compact at 0.65: 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 17.6 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 1621 18th St scores 60 out of 100
Daylight efficiency 66, Interior depth 61, Scale 59, Finance 39 — each out of 100, then weighted.
Score components for 1621 18th St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency73% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 66 | 45% | 29.8 |
| Interior depthdeepest interior point 56 ft from a facade, scored from 80 ft down to 40 ft | 61 | 25% | 15.1 |
| Scale88 estimated homes, scored from 0 up to 150 | 59 | 15% | 8.8 |
| Financeremaining gap is 36% of conversion cost, scored from 60% down to 0% | 39 | 15% | 5.9 |
Most of what it earns comes from daylight efficiency, and what holds it back most is finance, at 39 out of 100: remaining gap is 36% of conversion cost, scored from 60% down to 0%.
What the conversion would cost
$360 per square foot all-in across 113,796 sq ft of converted floor, or $41.0M in total — about $466K for each of the 88 homes.
All-in cost per square foot for 1621 18th St: base cost plus the code work a change of use triggers.
| Base conversion cost | $260/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 | $360/sq ft |
That cost is charged across every converted square foot, including the 30,620 sq ft of windowless core, which has to be gutted, re-plumbed and sprinklered like the rest of the building and then earns nothing. Against it the model sets a completed value of $236K a home, which for 88 homes is $20.8M.
What would have to be true
A $20.2M gap before any grant, $14.9M after the modeled one. The smallest single change that would close it: average unit size 36% down.
The shortfall before any grant is $20.2M. Closing it from the value side means each of the 88 homes finishing at $466K rather than the $236K the model assumes — 97% more. Closing it from the cost side means getting all-in cost down from $360 to $183 per square foot.
A modeled RESIDE grant of $5.3M moves that threshold to $406K a home. That is still above the $236K assumed, leaving $14.9M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 1621 18th St, one alone would close the gap at:
Single-assumption flip points for 1621 18th St, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 36% downto 479 sq ft |
|---|---|
| Conversion cost per square foot | 50% downto $129/sq ft |
| Completed value per home | 72% upto $406K |
All four are sliders in the survey, where 1621 18th St re-scores against your own numbers.
How it compares in Greater Downtown Denver
1621 18th St ranks 172nd of the 214 buildings screened here, against a median score of 72.
Its floor plate is better lit than 23% of them, and shallower than 54% of them at its deepest interior point. On size it is the 169th largest by estimated homes. The full survey of all 214 buildings ranks and maps every one of them, and the list by address links each to its own page.
Within Union Station and the D-LD zone
44th of 55 in Union Station, 25th of 29 zoned D-LD — the comparison that shares its rules, rents and streets.
Denver places 55 of the screened buildings in Union Station. 1621 18th St ranks 44th of them against a median score of 69. 23 score 70 or more, their median deepest interior point is 61 ft from a facade against this building’s 56 ft, and together they would hold an estimated 13,167 homes. The group’s top scorer is 1600 17th St, at 95.
29 of the screened buildings are zoned D-LD. 1621 18th St ranks 25th of them against a median score of 68. 10 score 70 or more, their median deepest interior point is 61 ft from a facade against this building’s 56 ft, and together they would hold an estimated 5,069 homes. The group’s top scorer is 1600 17th St, at 95.
Its nearest match in size: 1300 N Fox St
The screened building closest to 1621 18th St in converted floor area is 1300 N Fox St: 117,000 sq ft over 6 stories, against 113,796 sq ft over 6 here.
1621 18th St scores 60 to its 53, and with the size held roughly equal most of that lead comes from interior depth: 61 out of 100 here, 45 there (deepest interior point 62 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 6,000 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 1621 18th St $5.3M, 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 1621 18th St
The 4 closest the screen also covers, from 200 ft away. They are the colored outlines on the plan at the top of this page.
- 1801 Wynkoop St10 stories · 74% daylit · already a condominium buildingabout 200 ft away
- 1890 Wynkoop St8 stories · 84% daylit · 86 estimated homes · scores 69/100 (Worth a feasibility study)about 210 ft away
- 1863 Wazee St7 stories · 82% daylit · already a condominium buildingabout 260 ft away
- 1899 Wynkoop St12 stories · 76% daylit · 159 estimated homes · scores 65/100 (Worth a feasibility study)about 290 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.