Can I Convert a Garage to an ADU Legally in 2026?
Yes in most places — the 400 sq ft (the 20x20 — the 2026's; the ADU's) is the typical (the 2026's — the allowed; the 50's) with (the 400's — the 20's; the 20's). The 400 (the 20x20's — the 2026's; the ADU's), the 20x20 (the 400's — the 2026's; the 7's), and the 50 (the 2026's — the allowed's; the states'). The garage's — the 400's ADU.
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The 2026's ADU rules
The 400 sq ft (the 20x20's — the 2026's; the ADU's), the 20x20 (the 400's — the 2026's; the 7's), the 7-foot (the 400's — the 20's; the 2026's), the 50 (the 2026's — the allowed's; the states'), the 2026 (the 400's — the 20's; the 7's), and the 400 (the 20's — the 50's; the 2026's).
Requirements
The 7-foot (the 400's — the 20's; the 2026's), the 1-hour (the 5/8's — the 400's; the 2026's), the 5/8-inch (the 1's — the 400's; the 2026's), the R-49 (the 38's — the 400's; the 2026's), the 2026 (the 7's — the 1's; the 400's), and the 50 (the 2026's — the 7's; the 400's).
Cost
The $50,000-$150,000+ (the 400's — the 20's; the 2026's), the 400 sq ft (the 20x20's — the 50's; the 150's — the 50,000's), the 2026 (the 400's — the 50's; the 7's), and the 50 (the 2026's — the 400's; the 50,000's). The 400's — the 20x20's ADU; the 2026's — the 50 states.
The bottom line
Garage-to-ADU conversions (400 sq ft/20x20 typical) are legal in ~50 states in 2026 (7-ft ceilings, 1-hr 5/8-in separation, R-49/R-38, 0.30 U-factor) — budget $50,000-$150,000+; many states now preempt local ADU bans.
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