Need a home addition in Ada County, ID? Ada County has about 535,799 residents (2024 estimate) and 6 incorporated cities and towns. Describe your project once: addition contractors who work in Ada County get back to you.
Building permits in Ada County are issued by each city, or by the county in unincorporated areas.
Services available in Ada County
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Room addition
Ground-floor addition with foundation, framing, roof and finishes.
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Second-story addition
New floor over the existing house, with structural engineering.
Frequently asked questions in Ada County
Do addition contractors cover the whole of Ada County?
Most pros work across the county and neighboring counties. Enter your ZIP code in the form and we match you with pros who serve your exact area.
Home Additions in Idaho: all counties
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2024) and Gazetteer Files (public domain), imported on 10/31/2026. Figures describe the incorporated place or county as published; they are shown for information only.