Grandpa's ADU

Grandpa's ADU is a prototype detached ADU plan from City of Flagstaff Model Plans Library. The public source lists it as 682 sq ft and 1 bed; bathroom count is not listed. It originated in the Coconino County, Arizona, USA program. This directory currently shows acceptance in Coconino County, Arizona, USA. Source context comes from City of Flagstaff, last checked Sep 8, 2026. Use the linked provider, location, and source records to verify current acceptance before relying on the plan.

Provider record

City of Flagstaff Model Plans Library

Origin program

Coconino County, Arizona, USA

Accepted location pages

• Coconino County, Arizona, USA

Plan identifier

Not listed in source

Provider

City of Flagstaff Model Plans Library

Origin location

Coconino County, Arizona, USA

Accepted locations

• Coconino County, Arizona, USA (Accepted)

Status

Prototype

Size

682 sq ft

Bedrooms

1 bed

Bathrooms

Not listed in source

ADU type

Detached

Construction type

Unknown

Plan fee

Not listed in source

Estimated cost

Not listed in source

Last checked

Sep 8, 2026

Foundation notes

Foundation and snow-load modifications may be required by County location and elevation.

Utility notes

County permits gas-option modifications for additional designer compensation; other utilities remain site-specific.

Energy notes

Catalog features cite the 2024 IRC and 2024 IECC; County review still controls.

Accessibility notes

Not listed in source

Permit fee notes

County publishes a $1,000–$3,000 base range but not a reliable one-to-one fee for every design in the summary.

Cost notes

Not listed in source

Additional notes

Coconino County offers this Flagstaff catalog design but has not pre-reviewed it; comprehensive County and site review remain.

Publisher

City of Flagstaff

Source type

Plan catalog

Reliability

Official city/county/state government source (5/5)

Last checked

Sep 8, 2026

Accessed

Sep 8, 2026