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Building an ADU in West Des Moines: rules & permits

By Iowa Tiny Houses  ·  Updated July 2026  ·  5 min read

West Des Moines homeowners can build an ADU under Iowa's 2025 law.

Short answer: yes, you can build an ADU in West Des Moines. Iowa's 2025 state law (SF 592) requires every city in the state — West Des Moines included — to allow at least one accessory dwelling unit on a single-family lot. What's still settling is how WDM's own zoning code lines up with the new state rules.

Here's what applies today, and the one step that matters most before you design.

The state baseline that applies in WDM

Because SF 592 is a state mandate, these protections apply in West Des Moines no matter what the local code still says:

One ADU by right
At least one ADU allowed on a single-family lot, no discretionary hearing.
Size: 1,000 sq ft or half your home
Whichever is larger. Measured as gross living area — garages, decks, and unfinished basements don't count toward the cap.
No owner-occupancy rule
You don't have to live on-site — investors can rent it out.
No stricter rules than the main house
The city can't impose tougher setbacks, height, design-matching, or extra parking than it applies to your primary home.

Why West Des Moines is a little different: unlike the City of Des Moines, which has a dedicated ADU section in its zoning code, WDM doesn't yet publish a standalone ADU ordinance — its code is still being amended. In practice that means the state law governs your right to build, while the city applies its normal accessory-structure and permit standards. That's exactly why confirming with the city first matters more here.

Local things to check for your lot

PUD zoning. West Des Moines has many Planned Unit Developments — master-planned neighborhoods with their own rules. If your home is in a PUD, its specific standards may shape where and how an ADU can go, so this is the first thing to confirm.

HOA covenants. Many WDM subdivisions have active homeowners associations. State law limits the city, but a private HOA's covenants are separate — check yours before you plan.

Accessory-structure placement. WDM's code generally keeps detached accessory buildings out of the front yard and behind the main plane of the house — expect a rear-yard placement.

Utilities. Confirm water, sewer, and electric service to the ADU site with West Des Moines Water Works and MidAmerican Energy before you finalize a design.

Cost & return in West Des Moines

Costs track the rest of the metro: roughly $60–95k for a garage or basement conversion, $110–150k for a compact detached unit, and $160–190k for a premium detached build. WDM's strong rents can push returns a bit higher than the metro average, though labor demand here can also nudge build costs up. See our full cost breakdown and investment guide for the numbers.

In West Des Moines, the state law gives you the right to build — the local details are what you confirm before you design.

The one step to take first

Because WDM's code is still catching up to the state law, don't rely on a generic answer — confirm your specific parcel's zoning, PUD status, and permit path with West Des Moines Community & Economic Development before you commit to a plan. Or let us do it for you: we'll check your lot, confirm what's allowed, and put the cost and return in writing. For the full statewide picture, see our Iowa ADU guide, or compare towns on the by-city overview.

Thinking about an ADU in West Des Moines?

Tell us your address and we'll confirm what your lot allows and put the numbers in writing. Free, no obligation.

Based on Iowa Senate File 592 and current West Des Moines requirements; the city's code is being updated to match state law and rules vary by parcel. General information, not legal advice — confirm specifics with West Des Moines Community & Economic Development before you build.