Madison’s Housing Forward proposal to allow two ADUs on a single residential lot is a meaningful shift — and one of the most significant changes to Dane County ADU policy in years. Here’s what it means for homeowners and investors planning an ADU project.
What the Proposal Actually Allows
Under current Madison zoning, single-family residential lots are limited to one ADU. The Housing Forward proposal would allow two — either two detached units, or a combination of detached and attached. Both would need to comply with existing setback, lot coverage, and size requirements. Owner-occupancy is not required under current rules and that would not change.
What It Means for Homeowners
For homeowners with a large lot, two ADUs changes the calculus considerably:
- A parent can live in one unit while the second generates rental income to offset the build cost.
- Two long-term rentals on a single parcel in Madison’s rental market produce meaningful cash flow.
- A guest cottage and a rental unit can coexist on the same property without forcing a choice between them.
- The second unit adds assessed value without requiring a lot split or subdivision.
What It Means for Investors
For rental property owners, two ADUs on one lot is a fundamentally different investment structure. Madison’s rental vacancy rate has stayed below 3% in recent years. A two-ADU lot in a walkable neighborhood produces two income streams on one tax bill, with no shared hallways, no multi-unit licensing complexity, and no HOA.
The per-unit build cost on the second ADU is often lower than the first — site work, permitting coordination, and design overhead partially amortize across both units. It’s not half price, but it’s not linear either.
The Catch: Lot Size and Coverage
Not every lot qualifies. Madison’s existing ADU rules require minimum lot sizes, maximum lot coverage percentages, and setbacks from property lines. Adding a second ADU means both units need to fit within those constraints simultaneously. Large lots in districts like Nakoma, Waunakee, or McFarland have more flexibility. Compact urban lots in Madison proper may only support one unit regardless of what the ordinance permits.
A feasibility check on your specific parcel — evaluating lot size, setbacks, and coverage — is the right first step before assuming two units will work.
Timeline
The Housing Forward proposal was under review through late 2025. If adopted, implementation typically follows within 6–12 months of council approval. We’re monitoring the ordinance closely and will update this post when the status changes. In the meantime, if you’re planning ahead for a two-ADU project, starting the feasibility and design process now puts you in position to move quickly when the rules are final.
Questions about whether your lot qualifies? Schedule a free feasibility check and we’ll review your specific parcel.
