New Colorado Law Eases Accessory Dwelling Unit Construction in Douglas County

Limestone Custom Homes, a design-build firm based in Castle Rock, Colorado, has stated that the 2026-2027 building season is poised to be a prime time for Douglas County homeowners to construct accessory dwelling units (ADUs). This is largely due to Colorado's state law HB24-1152, effective since June 30, 2025, which mandates that jurisdictions including Castle Rock, Parker, Lone Tree, and unincorporated Douglas County must allow one ADU per single-family lot through an administrative approval process.

The new legislation streamlines the ADU building process by removing common obstacles. Jurisdictions can no longer typically require additional off-street parking for an ADU, impose owner-occupancy requirements, or apply stricter design standards than those for the primary residence. Furthermore, the law invalidates restrictive covenants within homeowners' associations (HOAs) that prohibit ADUs, a significant change in HOA-prevalent areas like Douglas County, although HOAs may still enforce reasonable design standards.

According to Limestone Custom Homes, common motivations for Douglas County homeowners seeking to build ADUs include creating housing for aging parents or adult children, generating rental income to offset rising housing costs, establishing home offices or studios, and accommodating guests. Many homeowners are planning units that can serve family needs initially and transition to rentals later.

"Douglas County homeowners have wanted to build ADUs for years. The process was the obstacle," a Limestone Custom Homes spokesperson commented. "With administrative approval now being the standard, homeowners who had shelved ADU plans are taking a second look. The path is much clearer than it was previously."