Wednesday, October 22, 2014

Movement growing toward legalizing tiny houses—120 square foot requirement eliminated from building code!

According to Tom Meyer, a building official active in the revision of modern building codes that inhibit affordable and sustainable residential construction, the requirement that each dwelling have at least one habitable room of 120 square feet has been eliminated in the 2015 International Residential Code. Below we see a view of the new 2015 IRC, courtesy of Meyer:


This came as a surprise to me as I recently wrote a post titled, "Navigating minimum square footage requirements for tiny houses WITHOUT a trailer — International Residential Code says it can be as little as 138 square feet"

My point was that the minimum area regulations were not that bad, and that it is in fact municipal ordinances—not the building code—that are the real legal barrier to building tiny houses. But this change will make the building code even less of an issue—allowing for a legal dwelling under 100 square feet.

Now all habitable room just have to meet the minimum area of 70 square feet and height of 7 feet (already the requirement for all "other habitable" rooms besides the previously required 120 square foot room).

In a previous post back in 2010, Meyer notes that he is also responsible for adding the exemption for kitchens not having to meet minimum area requirements, allowing the kitchen to not have to have its own designated room:

"Kitchens are deeded habitable, but are exempt from the minimum room area. Earlier editions of the code required 50sf for this location. The current exception was also one of my code changes. If was quite a battle to get the ICC membership to delete this requirement. However, we prevailed. Based on this experience, it may be quite difficult to delete the 120sf and 70sf minimums in future codes. However, I think that a proposal to do so is certainly worth consideration for the 2015 edition."

And it looks like his proposal was indeed worth consideration. See his argument for removing the 120 square foot room requirement below:


Meanwhile, Eli Spevak has put out a proposal titled "A Legal Path to Tiny Homes in Portland." The proposal would allow for both small auxiliary structures (under 200 square feet) and tiny houses on wheels to be legally accepted as habitable structures, provided they meet a property maintenance code and receive a "temporary certificate of occupancy."

Read Spevak's full tiny house proposal here.

I have been working on a proposal of my own for a municipal ordinance that would allow for tiny house developments (THDs)—allowing for the development of tiny house communities on parcels in residential zones. To develop this ordinance, I'm drawing from Ross Chapin's extensive work with "pocket neighborhoods" and the "cottage housing" codes he helped craft around Seattle. More on that soon.

Pocket Neighborhoods by Ross Chapin

Follow-Up Post: "A Legal Path for Tiny House Communities"


  1. The ceiling height is debatable as it should be relational to the height of the occupant (s). One might suggest that a person under 6 foot tall only be required to have a ceiling clearance of just under 7 foot where a sloped gothic arched or quonset hut shaped roof is present. A person taller might need a greater clearance if they desired. Put if quality built small buildings no wider than 8.5 feet are needed and can accomodate shorter people at a lower cost why sentence them to a code that creates more costs for them and wind problems. A lower roof height profile is better structurally. Most basements have seven feet ceilings. People are use to living in finished basements as a lifestyle.

  2. I am puzzled because R304.5 of California Residential Code requires that an efficiency unit (one room residence) have a minimum floor area of 220 sqft.

    R304.5 Efficiency dwelling units. (HCD 1) Unless modified by local ordinance pursuant to Health and Safety Code Section 17958.1, efficiency dwelling units shall comply with the following:
    1. The unit shall have a living room of not less than 220 square feet (20.4 m2) of floor area. An additional 100 square feet (9.3 m2) of floor area shall be provided for each occupant of such unit in excess of two.
    2. The unit shall be provided with a separate closet.

    3. The unit shall be provided with a kitchen sink, cooking appliance and refrigeration facilities, each having a clear working space of not less than 30 inches (762 mm) in front. Light and ventilation conforming to this code shall be provided.
    4. The unit shall be provided with a separate bathroom containing a water closet, lavatory and bathtub or shower.

  3. is this apply in most/every states,including indiana?