Straight answers
What is IRC Appendix Q?
Appendix Q is the part of the International Residential Code written for tiny houses under 400 square feet. It adjusts requirements that a full-size code makes impractical at that scale, covering things like stairs, ladders, headroom and lofts, so a small home can be built and permitted as a real dwelling rather than treated as an undersized house.
01 — The longer answer
Why adoption is the catch with Appendix Q
The catch is adoption. Appendix Q is not applied uniformly: it is adopted jurisdiction by jurisdiction, and in some places that is happening as late as 2027. A home built to it is not automatically permittable everywhere.
That is why any claim about permittability has to be checked against the actual destination rather than assumed from the code alone. We publish what we have verified for each state, and we confirm the local position before a build starts.
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