Restrictive Zoning Blocks Affordable Housing Across Colorado, Study Finds
A landmark study from the National Zoning Atlas has revealed just how restrictive Colorado’s land use codes really are, and why affordable housing remains out of reach for so many. Researchers reviewed more than 53,000 pages of zoning codes from 334 jurisdictions across the state. Their conclusion: while single-family homes can be built almost anywhere, more affordable housing types are often outright prohibited.
The findings are stark. Nearly 70% of residentially zoned land in Colorado bans multifamily housing. Only 3% of land allows projects with four or more units by right, and duplexes are permitted on just one-third of residential land. Minimum lot sizes are also widespread; in fact, Colorado has the largest average lot size requirements among the 10 states studied so far. Many jurisdictions require half-acre or even two-acre lots, making smaller, more affordable homes financially unfeasible.
Parking mandates add another layer of cost. About 85% of Colorado’s residential land requires at least two parking spaces per unit, inflating construction expenses by thousands of dollars per spot. Accessory dwelling units (ADUs), often considered a win-win solution, are banned or heavily restricted in more than half of the state’s communities.
These restrictions have a ripple effect on affordability. Larger lots and costly parking requirements increase material and labor costs, driving up home prices. Limited opportunities for duplexes, townhomes, and condos block what housing advocates call the “missing middle”, units that are less expensive than single-family homes but more accessible than large apartment complexes.
The consequences are clear: Colorado consistently ranks among the top states for highest housing costs, with more than 420,000 renter households considered cost-burdened. Advocates say the report provides critical evidence for reform. State leaders have already moved to relax some restrictions, passing laws to expand ADUs and eliminate parking minimums near transit. Cities like Longmont and Denver are going further, lifting mandates entirely.
Still, opposition remains strong, with local officials and homeowners pushing back on state intervention. “Zoning is like the plumbing of our housing system,” said economist Luke Teater. “You don’t think about it until it breaks, but it shapes everything else.”
The Zoning Atlas recommendations include legalizing small lots, loosening multifamily restrictions, streamlining permitting, and expanding ADU protections. Without change, researchers warn, Colorado will continue producing only the most expensive types of housing, leaving affordable options scarce.
