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Westminster spans Jefferson and Adams counties with neighborhoods ranging from established ranch homes to newer subdivisions. Here’s what ADU rules look like in Westminster today.
Westminster has updated its zoning code to comply with Colorado’s HB 24-1152, enabling ADU construction on single-family lots. The city spans two counties and a range of neighborhood types — from older 1960s ranch homes in south Westminster to newer construction near US-36.
ADU applications in Westminster are processed administratively — no public hearings if your plans meet objective zoning standards. Setbacks mirror those applied to other accessory structures. No off-street parking is required in most cases. Maximum size is 800 sq ft.
Basement ADUs ($35K–$100K): Ranch-style homes throughout south Westminster have excellent basement conversion potential — often the quickest and most affordable ADU path.
Detached Backyard Cottages ($165K–$325K): Lots in many Westminster neighborhoods accommodate rear detached construction. US-36 access and proximity to Boulder creates steady rental demand.
Garage Conversions ($40K–$120K): Detached garages common in older Westminster neighborhoods convert efficiently and typically require less investment than new construction.
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