Village of Mt Horeb, WI ADU Regulations
Village of Mt Horeb at a glance:
Maximum Size:
800 Sqft
Maximum Size:
800 Sqft or 75% of Primary Dwelling Footprint (whichever is less)
Height Limit:
Less than 50% of Primary Structure's Roof Pitch ft
Side Setbacks:
8 ft
Rear Setback:
5 ft
Owner Occupancy Required?
Yes
Conditional Use Permit Required?
No
Two Story Allowed?
No
Soils Report needed?
No
Park Impact Report Needed?
No
In Mount Horeb, WI, building an ADU is possible (as of March 2026), but the Village has a few requirements that need to be understood before moving forward. Owner-occupancy is mandatory — the property owner must live on-site for at least 10 months per year.
One rule in Mount Horeb's ADU ordinance stands out from most municipalities in Dane County: building height isn't just capped by your zoning district's standard maximum — it's also limited to 50% of the principal structure's total roof pitch. In practice, this means a home with a shallow or low-pitched roof can significantly constrain how tall your ADU can be, even if the district would otherwise allow more. This is an unusual requirement that doesn't show up in most local ordinances, and it's exactly the kind of detail that can redirect a design mid-process if it isn't caught early. We review roof pitch as part of every Mount Horeb feasibility check so your design is built around what's actually permitted — not revised after the fact.
Rear setbacks: Old Village R1/R2 (30ft), Regular R1 (35ft), Regular R2 (40ft)
Due to the unusual height requirement, significant rear setbacks and owner-occupancy requirement, we've given Mt Horeb a feasibility score of 6/10.
For homeowners who meet the owner-occupancy requirement and can work within these parameters, Mount Horeb is a workable and ADU-friendly community.
