ADU ConstructionOct 25, 2025
ADU Builder's Guide: Add a Rental Unit to Your Utah Property in 2025
Utah's new 2025 ADU laws make it easier than ever to add a mother-in-law apartment, backyard casita, or rental unit — and skyrocket your property value. W Builders has built dozens across Salt Lake, Utah, and Washington counties. Here's exactly what you need to know right now.
2025 Utah ADU Rules (Simplified)
- Up to 1,200 sq ft detached or 900 sq ft attached
- One ADU + one JADU allowed on single-family lots
- No owner-occupancy requirement in most cities (St. George, Provo, Lehi, etc.)
- Separate utilities no longer required in many municipalities
- Fast-track permitting in Salt Lake City and Ogden
Average Costs in 2025
- 600–800 sq ft detached ADU: $140,000 – $210,000
- Garage conversion: $80,000 – $130,000
- Basement apartment: $60,000 – $110,000
- Average ROI in Utah: 80–120% within 5 years through rent or resale
Timeline Most Homeowners See
- Design & permits: 4–8 weeks
- Construction: 12–20 weeks
- Total: 4–6 months start to move-in
Biggest Money Mistakes to Avoid
- Skipping the utility impact fee study (can add $15k+ surprise)
- Building too small to legally rent long-term
- Choosing a contractor who's never pulled an ADU permit before
Ready to add instant equity and rental income? Text or call W Builders for a free ADU feasibility check and accurate quote. We handle every city requirement from Ogden to St. George. Your extra paycheck (or family space) starts here.