Earlier this month the International Code Council (ICC) approved new building code specifically addressing tiny houses on a foundation.
Appendix Q is now part of the 2018 International Residential Code for One- and Two-Family Dwellings (IRC), which is the model code upon which states and communities base their own building codes. In other words, the IRC is not effective, until it is adopted by a local jurisdiction–which can take months or years to happen–and the local jurisdiction can make changes to the code, before adoption. So there is no guarantee that Appendix Q will be adopted as is in all 50 states, but the fact that it’s now part of the IRC code makes it a lot more likely that tiny houses will soon be addressed in the building codes across the United States.
Appendix Q relaxes various requirements in the body of the code as they apply to houses that are 400 square feet in area or less. Attention is specifically paid to features such as compact stairs, including stair handrails and headroom, ladders, reduced ceiling heights in lofts and guard and emergency escape and rescue opening requirements at lofts. —codes.iccsafe.org
The IRC is also used as model code in Abu Dhabi, the Caribbean Community, Colombia, Georgia, Honduras, Afghanistan and Saudi Arabia–so tiny houses may be addressed soon in those countries as well.
To see the full text of Appendix Q, go to https://codes.iccsafe.org/public/document/IRC2018/appendix-q-tiny-houses