How Big is a Tiny House?

You may have heard that a tiny house is under 500 square feet–or 1000 square feet. Real Estate agents routinely refer to any house under 2000 square feet as tiny. And for some, anything over 200 square feet isn’t what they consider tiny, and definitely not a proper tiny house.

So what is the official definition of a tiny house? How many square feet can it be, and still qualify as tiny? For many years there was no official definition of a tiny house–so everyone was free to make up their own definition! But recently things have changed.

As of August 2017, when the International Code Council (ICC) approved Appendix Q we got model code with an official definition of a tiny house. The 2018 International Residential Code for One- and Two-Family Dwellings (IRC) defines a tiny house as…

TINY HOUSE. A dwelling that is 400 square feet (37m2) or less in floor area excluding lofts.

That’s the entire definition. There’s nothing more to it! The thing that defines a tiny house officially, is that it’s under 400 square feet.

Of course Appendix Q only applies to tiny houses on a foundation, and not moveable tiny homes–so what about tiny houses on wheels? How big can a tiny house on wheels be? That depends on where you live, but in any state that defines a tiny house on wheels as an RV, then the maximum size for a tiny house RV is 400 square feet, according to the NFPA 1192 Standard for RVs. If you’ve ever seen a park model RV, they are often around 12′ wide and 33′ long, just under the 400 square feet maximum.

So with the IRC now defining a tiny house on a foundation as under 400 square feet. And with the ANSI Standard for RVs also allowing for a maximum of 400 square feet for tiny house RVs, it seems we now have an answer to the question of how big is a tiny home. Any home that is under 400 square feet in area, excluding lofts, whether it is on a permanent foundation or on wheels, fits the definition of a tiny house!

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Appendix Q: Tiny Houses

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

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