Hey BP community. I have been lurking here for a while and finally posting. Based in Aurora, been spending the last several months doing a deep dive into ADU feasibility and house hacking math specifically for the Denver Metro. I also wonder if it makes sense to build a modular house vs an adu. I found a company in Loveland that does them but still doing research.

A few things I learned that surprised me and might be useful for others looking at Colorado:

Colorado's ADU law changed significantly in June 2025. HB 24-1152 made ADUs a permitted use by right on essentially any single-family lot in the Denver Metro — no public hearings, no rezoning, just administrative approval. HOAs can no longer ban them outright either. Most people buying in Denver right now don't know this changed.

Construction costs are the real obstacle, not zoning. Detached new builds are running $280-320/sqft which makes the pure ROI math difficult. And after speaking with multiple builders this is the low end of the cost estimate as it could be way higher.

But basement conversions are $130-160/sqft and that's where the numbers actually work for most house hackers. The payback window drops from 15+ years to 5-6 years and the financing is much more manageable.

Permit timelines vary wildly by city. Denver proper averages 8-12 weeks for ADU review. Unincorporated Arapahoe County is 12-18 months. That variance alone can make or break a financing plan.

The financing piece is underrated. A land use planner I talked to recently made the point that financing — not zoning — is the actual barrier for most homeowners considering ADUs. Tap fees, construction loan terms, and HELOC eligibility are where most projects stall out, not the permitting itself.

Happy to share more of what I've found if it's useful. Also genuinely curious what others are seeing in other markets — are construction costs starting to come down anywhere or is $300/sqft the new normal everywhere? Or are my estimates too low? What have you found?