515 17th St

515 17th St is a 42-story building in Greater Downtown Denver with 77% of its floor area within daylight reach of a facade. This screen estimates 1,110 homes and scores it 65 out of 100 for office-to-residential conversion suitability.

CO-1 · Screened 2026-09-19 · Worth a feasibility study

Build a conversion planCheck its numbers, lay out its homes and get a two-page PDF. Free.

Also addressed as 555 17th St, 500 18th St, 1700 Welton St, 1750 Welton St and 1760 Welton St: Denver’s address records place all 6 on this one footprint.

Where 515 17th St is

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

Suitability score

0–29

30–49

50–69

70–100

Already housing
Not screened
515 17th St

515 17th St and the 1,000 ft of Greater Downtown Denver 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. 515 17th St is outlined in its own score color at the outline it covers at ground level. Dashed inside it is the typical floor, the one the floor-plate figure below draws, because this building steps back as it rises. Its windowless core is hatched. The inset places it among every building the screen covers.

Typical floor plan: 77% of the building’s floor area sits within daylight reach of a facade; the drawing shows its typical floor, where the share is 86%. The shading is daylight, darkest at the windows and gone 35 ft in. The hatched area is windowless core: 4,681 sq ft per typical floor that must be renovated but can never be rented as an apartment. The dimension marks the deepest interior point, 60 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: 4,681 sq ft on the floor the screen scores, and 314,096 sq ft over 41 residential floors. The steps are where the building sets back as it rises. 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.

Across its 41 residential floors this building carries 314,096 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 515 17th St, 2026-09-19.

Suitability scoreWorth a feasibility study	65 / 100
Storiesfrom 510 ft aerial-survey height ÷ 12 ft floor-to-floor	42
Height bandsfloor plate by floor range, from the city's roof outlines	Floor 1: 95,706 sq ft · Floor 2: 95,264 sq ft · Floor 3: 91,935 sq ft · Floor 4: 90,742 sq ft · Floor 5: 89,553 sq ft · Floor 6: 62,750 sq ft · Floor 7: 38,193 sq ft · Floors 8–22: 32,993 sq ft · Floors 23–24: 20,763 sq ft · Floors 25–41: 19,577 sq ft · Floor 42: 17,981 sq ft
Floor platetypical floor, from the city outlines	32,993 sq ft
Daylight efficiencyshare within 35 ft of a facade	77%
Deepest interior pointviability threshold is 80 ft	60 ft
Windowless coretypical floor; the building-wide total is in the text above	4,681 sq ft
Estimated homesat 750 sq ft average	1,110
Conversion cost$360/sq ft all-in on 1,355,639 sq ft	$488.0M
Gap before grantshortfall against completed value	$226.1M
Modeled RESIDE grantat the statutory per-award cap	$10.0M
BuiltDenver does not publish a construction year with this data	—
ZoningCBD	D-C
Opportunity Zonenot in a 2018 designated tract	No

The plan: window line, shape and floor rhythm

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

The typical floor has 1,113 ft of exterior wall, and across 41 residential floors the building carries 39,945 ft of it in total, divided among the 1,110 homes this screen estimates.

Its plate is elongated at 0.33: 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 27.1 homes per floor. Its floors are not alike, though: the typical floor's deepest interior point is 60 ft from a facade, while its worst floor reaches 110 ft. The score follows the typical floor, so a podium that could not hold a bedroom does not by itself sink a slim tower above it — but it is there, and it is part of what would have to be drawn around.

Why 515 17th St scores 65 out of 100

Daylight efficiency 74, Interior depth 50, Scale 100, Finance 26 — each out of 100, then weighted.

Score components for 515 17th St. Points are the subscore times its weight.

Component	Subscore	Weight	Points
Daylight efficiency77% of the floor area within 35 ft of a facade, scored from 40% up to 90%	74	45%	33.1
Interior depthdeepest interior point 60 ft from a facade, scored from 80 ft down to 40 ft	50	25%	12.4
Scale1110 estimated homes, scored from 0 up to 150	100	15%	15.0
Financeremaining gap is 44% of conversion cost, scored from 60% down to 0%	26	15%	3.9

Most of what it earns comes from daylight efficiency, and what holds it back most is finance, at 26 out of 100: remaining gap is 44% of conversion cost, scored from 60% down to 0%.

What the conversion would cost

$360 per square foot all-in across 1,355,639 sq ft of converted floor, or $488.0M in total — about $440K for each of the 1,110 homes.

All-in cost per square foot for 515 17th 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 314,096 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 1,110 homes is $262.0M.

What would have to be true

A $226.1M gap before any grant, $216.1M after the modeled one. The smallest single change that would close it: average unit size 45% down.

The shortfall before any grant is $226.1M. Closing it from the value side means each of the 1,110 homes finishing at $440K rather than the $236K the model assumes — 86% more. Closing it from the cost side means getting all-in cost down from $360 to $193 per square foot.

A modeled RESIDE grant of $10.0M moves that threshold to $431K a home. That is still above the $236K assumed, leaving $216.1M uncovered, which is why the grant does not unlock this one.

Nor do all four levers have to move. For 515 17th St, one alone would close the gap at:

Single-assumption flip points for 515 17th St, each holding the other three at their defaults.

Average unit sizethe binding constraint — the least this building would need	45% downto 411 sq ft
Conversion cost per square foot	61% downto $101/sq ft
Completed value per home	82% upto $431K

All four are sliders in the survey, where 515 17th St re-scores against your own numbers.

How it compares in Greater Downtown Denver

515 17th St ranks 145th of the 214 buildings screened here, against a median score of 72.

Its floor plate is better lit than 33% of them, and shallower than 43% of them at its deepest interior point. On size it is the 11th 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 CBD and the D-C zone

53rd of 75 in CBD, 51st of 72 zoned D-C — the comparison that shares its rules, rents and streets.

Denver places 75 of the screened buildings in CBD. 515 17th St ranks 53rd of them against a median score of 71. 40 score 70 or more, their median deepest interior point is 56 ft from a facade against this building’s 60 ft, and together they would hold an estimated 33,698 homes. The group’s top scorer is 918 17th St, at 97.

72 of the screened buildings are zoned D-C. 515 17th St ranks 51st of them against a median score of 73. 39 score 70 or more, their median deepest interior point is 57 ft from a facade against this building’s 60 ft, and together they would hold an estimated 32,881 homes. The group’s top scorer is 721 19th St, at 95.

Its nearest match in size: 621 17th St

The screened building closest to 515 17th St in converted floor area is 621 17th St: 1,310,204 sq ft over 36 stories, against 1,355,639 sq ft over 42 here.

515 17th St scores 65 to its 84, and with the size held roughly equal most of that shortfall comes from interior depth: 50 out of 100 here, 98 there (deepest interior point 41 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 300 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 515 17th 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 515 17th St

The 4 closest the screen also covers, from 290 ft away. They are the colored outlines on the plan at the top of this page.

475 17th St
18 stories · 86% daylit · 260 estimated homes · scores 75/100 (Strong candidate)
about 290 ft away
621 17th St
36 stories · 84% daylit · 1,169 estimated homes · scores 84/100 (Strong candidate)
about 330 ft away
1801 N Broadway
20 stories · 84% daylit · 232 estimated homes · scores 77/100 (Strong candidate)
about 430 ft away
444 17th St
12 stories · 100% daylit · already a condominium building
about 430 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.