Can I Build Second Story Addition in Milwaukee, WI? (2026)
Find out if you can build a second story addition in Milwaukee, WI. Rules, permit requirements, costs, and next steps.
Adding a second story in Milwaukee, WI is possible in most zones, subject to height limits and structural permit requirements.
A second story addition is one of the most complex home improvement projects in Milwaukee, WI. It requires a full building permit, structural engineering review, and must comply with the height limits for your zoning district. Unlike a ground-floor addition, a second story changes the roofline and structural load path of your entire home, triggering stricter engineering requirements. In Milwaukee, zone height limits range from 30 feet in RT1 zones — verify your zone before planning.
Second Story Addition Rules in Milwaukee
Second Story Addition Rules in Milwaukee: Building permit required: Yes — all second story additions require a permit. Permit thresholds: All structural additions. Example height limit (RT1): 30 feet, max 2 stories. Structural engineering drawings required. Setbacks apply to the full structure height. Milwaukee DNS permit required with architectural plans. Milwaukee's two-flat housing stock generates significant addition and renovation activity as properties are rehabbed.
Costs & Fees
Second story addition permit fees in Milwaukee: Based on construction value — typically $800-$4,500. Note: structural engineering fees ($2,000–$10,000+) are separate from permit fees.
Timeline
Plan check: 3-6 weeks. Construction typically 3-6 months for a full second story.
Next Steps
Next steps for adding a second story in Milwaukee: 1. Hire a structural engineer to assess your existing foundation and framing capacity. 2. Confirm your zone height limit and verify the addition meets all setback requirements. 3. Submit full structural plans and permit application to the Milwaukee Department of Neighborhood Services (DNS). 4. Inspections required at foundation reinforcement, framing, shear panels, and final.
Milwaukee Department of Neighborhood Services (DNS)
Phone: (414) 286-2268
Website: https://city.milwaukee.gov/DNS
Online Permits: https://city.milwaukee.gov/DNS/Permits
Frequently Asked Questions
What is a Polish Flat and how does it affect ADU rules in Milwaukee?
A Polish Flat is a distinctive Milwaukee architectural type — a two-story house where the main living floor is elevated above a lower-floor apartment, with the front foundation visible between the ground and the elevated porch. This type was developed by Milwaukee's Polish immigrant community in the early 1900s as a built-in ADU. Many Milwaukee properties already function as two-family homes because of this tradition. If your Polish Flat has a lower-floor unit, it may require proper permitting and a Milwaukee rental housing license to legally operate as a rental.
Can I rent out a room or my whole home short-term (Airbnb) in Milwaukee?
Yes. Milwaukee requires a Short-Term Rental License ($150/year) for rentals under 30 consecutive days. Wisconsin Act 59 of 2017 prevents Milwaukee from banning STRs of 7 or more consecutive days outright, though Milwaukee may impose licensing requirements, safety standards, and density limits. Wisconsin state sales tax (5%) applies to STR revenues. Contact Milwaukee DNS or the City Clerk for current licensing requirements.
Can I build an ADU (carriage house or in-law suite) in Milwaukee?
Yes. Milwaukee's Zoning Code allows detached ADUs (often called carriage houses) of up to 900 sqft in the rear yard of residential properties. One parking space is required unless you're near a transit corridor. No owner-occupancy requirement. A building permit from Milwaukee DNS is required, and occupied rental units need a Milwaukee rental housing license. Contact Milwaukee DNS at (414) 286-2268.
What is Wisconsin Act 59 and how does it affect Milwaukee STRs?
Wisconsin Act 59, enacted in 2017, partially preempts local short-term rental bans. It prohibits Wisconsin municipalities (including Milwaukee) from completely banning short-term rentals of 7 or more consecutive days in residential zones. Milwaukee can still regulate STRs through licensing, density limits, safety requirements, and fire code compliance — it just cannot impose an outright ban on 7-night-or-longer rentals. Rentals shorter than 7 nights retain more local regulatory flexibility.
What permits are needed to convert a Milwaukee basement into a legal apartment?
Converting a Milwaukee basement or lower-floor unit to a legal apartment requires a building permit from Milwaukee DNS for the construction/renovation work (electrical, plumbing, egress windows, ceiling height compliance), plus a Milwaukee Rental Housing License for the occupied unit. Minimum ceiling height for habitable space is typically 7 ft. Egress windows are required for basement bedrooms. Fire separation between units may be required. Contact Milwaukee DNS at (414) 286-2268 for a pre-application meeting.
Source: Milwaukee Department of Neighborhood Services (DNS) — Building Regulations. Last verified April 6, 2026. View source