Denver, CO Building Safety: Anti-Mansionization (2026)
Key Facts
- Citation
- Denver Zoning Code § 13.1.4.2
- Rule type
- Sloped bulk plane, not flat setback
- Enforced by
- Community Planning and Development, permit review
- Purpose
- Reduce building mass on adjoining properties
- Applies to
- New construction and additions citywide
Summary
Denver's zoning code requires new buildings to step back under a sloped bulk plane rising from the side zone lot lines, preventing boxy additions and oversized houses from towering over neighboring yards.
A. Intent To shape building forms to reduce effect of massing on adjoining properties.
B. Rule of Measurement The bulk plane is measured starting from the Base Plane(s) established in Section 13.1.2.2, then rising vertically to a point (A) above the Base Plane(s) at the side zone lot lines for a distance established by the applicable building form standards. From this point above the Primary Base Plane, the bulk plane slopes (B) inward toward the center of the zone lot at an angle with respect to the horizontal established by the applicable building form standards. See Figure 13.1-24.
DENVER ZONING CODE June 25, 2010 | Republished February 25, 2025
| 13.1-15
Full Breakdown
Denver Zoning Code § 13.1.4.2 uses a bulk plane to shape building forms and reduce the effect of massing on adjoining properties. Measurement starts at the base plane, then rises vertically at the side zone lot lines to a height set by the applicable building form standards, after which the plane slopes inward toward the center of the zone lot at an angle set by those same standards. Because upper portions of a house must pitch back from the side lot lines, new construction and additions can't wall off a neighbor's yard with a flat, full-height side: this is Denver's tool for curbing mansionization without a single citywide size cap.
Violations & Fines
Bulk plane setback violations are enforced by Denver Community Planning and Development through the zoning permit review process; noncompliant plans are rejected before a building permit issues, and built violations can trigger a stop-work order and require reconstruction to conform.
Frequently Asked Questions
What is a bulk plane in Denver zoning?
Does Denver cap house size to prevent mansionization?
Sources & Official References
Other rules in Denver
Compare Denver to another location·View the Colorado building safety overview
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