ADUs are allowed in JohnstonTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Johnston, IA
Is your property eligible for an ADU?
# of Properties
7,791
Owner-occupied
86%
Zoning districts
75
Avg Home Value
$402,325
Median Lot Size
0.27 acres
Avg Income
$143,076
Residential Types:
7,791 housing units
Other
100%
Zoning Districts:
9,997 parcels · 75 districts
R-1(75
20%(2,006)
R-1(60
11%(1,065)
R-1(100
10%(1,048)
PUD/PZ-07-52
5%(541)
Other
53%(5,337)
ADU Rules
What can you build in Johnston, IA?
Johnston, IA follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.
Eligibility
- –Internal / Attached ADU: By Right
- –Detached ADU: By Right
Interior / Attached ADU Size Limits
- –Maximum size of 900 sq ft
Detached ADU Size Limits
- –Maximum detached ADU size of 900 sq ft
- –Maximum ADU size limited to 10% of total lot area (counts toward total detached accessory structures)
- –Maximum ADU size capped by Table 177.1 based on lot size (counts toward total detached accessory structures)
Owner Occupancy
- –No owner-occupancy requirement for ADUs.
Parking
- –2 off-street spaces per ADU (and at least 2 for the principal residence); no waivers; spaces must be within a structure or on a paved, dustless surface and available to owner-occupants and tenants
What's allowed on your lot?
These are the municipality-wide rules. What's allowed on a specific property also depends on state laws, setbacks, floor area ratio, lot coverage, environmental constraints, topography, and other property-specific factors. Search your address on FutureLot to see what's allowed on your property.
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ADU rules in other Iowa municipalities
Rules change at the town line. Check the municipality your property is actually in.
Polk County