Boulder County, CO — ADU Specialists
Detached ADU Builders in Boulder County:
Backyard Suites & Guest Houses
ADU (Accessory Dwelling Unit) searches in Colorado have tripled since 2022 as housing laws changed and rental demand surged. Josh Brooks Construction designs and builds detached ADUs that maximize your lot value, generate rental income, and pass every inspection.
✓ Boulder County License CON-24-0152
✓ 31 Years Local Construction
Why Boulder County ADUs Are Booming in 2026
Colorado’s 2023 land use legislation (HB23-1255) made it significantly easier to build ADUs on single-family lots statewide. Cities like Longmont, Boulder, and Louisville have updated their codes to streamline ADU permitting. The result: a property owner with a qualifying lot can now build a legal rental unit, guest house, or multi-generational living space without a zoning variance in most cases.
In the Longmont rental market, a 500 sq ft ADU generates $1,500–$2,200/month — covering most or all of a mortgage payment for many homeowners.
ADU Types We Build
Detached Backyard ADU
A fully independent structure in your backyard with its own entrance, kitchen, bathroom, and utilities. Maximum privacy for renters or family. Most common in Longmont’s established neighborhoods. 400–800 sq ft.
Garage Conversion ADU
Converting an attached or detached garage into living space is the most cost-effective ADU path. Existing foundation, framing, and roof dramatically reduce construction cost. Typical budget: $90,000–$140,000.
Attached ADU Addition
An addition to your home with a separate entrance — ideal for multi-generational living where proximity matters but privacy is still required. Common configuration for aging parents or adult children.
Boulder County ADU Requirements (2026)
| Requirement | Typical Standard (Longmont) |
|---|---|
| Maximum ADU Size | Up to 1,000 sq ft or 50% of main house (whichever is less) |
| Setbacks (Detached) | 5 ft sides, 5 ft rear (verify per lot zone) |
| Owner Occupancy | Required in many Longmont zones (one of: primary or ADU) |
| Parking | 1 additional off-street space may be required |
| Utility Connections | Separate electric meter typically required; water/sewer may be shared |
* ADU regulations vary by jurisdiction. Josh Brooks Construction performs a zoning analysis for your specific property before any work begins.
Build Your ADU with Northern Colorado’s GC
We analyze your lot, confirm zoning, design to your goals, pull every permit, and build your ADU from foundation to finish — one contract, one point of contact.
Call 720-828-7997
Free ADU Consult
2167 Frontier St, Longmont CO 80501 | Boulder County License CON-24-0152 | $1M/$2M GL Insured | Senior & Veteran Discounts
Sources & Further Reading
● National Association of Home Builders — Remodeling Market Data
● Colorado DORA — Verify Contractor License
● OSHA Construction Safety Standards