[Greenbuilding] minimum house size if one follows building codes

[Chris Green]

Reuben Deumling wrote:
> Is it true that the sum of all requirements, clearances, etc. in the
> prevailing US building codes preclude building, say, a 250 square foot
> house? Assuming the codes work this way, has anyone tried to total up
> what the minimum permissible size might be?
>   
This weekend, having gotten the Small Strawbale book from the library, I 
have been discovering just how small a house is possible.
Suddenly 250 square feet looks big.
Designer Jay Shafer lives in a house about 100 square feet. One of his 
designs is 96 square feet, and is quite mobile since it's built on a 
travel trailer chassis. (One way to get around local minimum size 
restrictions... )
http://www.tumbleweedhouses.com/home.htm

This week in the UK a company has an 64 square foot "box"  on display at 
Birmingham's Extreme Buildings Festival. This is meant to be a complete 
livable home, since it includes a bathroom, kitchenette, dining area, 
and a bed that folds down when you want to sleep.
This thing is exactly the same size as my bathroom...
To get something this small to work one probably to design them with a 
lot of dual-use features and with the attention to detail used on the 
International Space Station. (Taking even a short shower or boiling too 
much water on the stove would probably turn the whole interior space 
into a steam bath...)
The BBC News article about this has a short video describing the 
reporters' experience of staying the night in this structure. Worth 
watching just to see how the bed is placed in the structure.
http://news.bbc.co.uk/1/hi/magazine/6733385.stm

A salvor and antique shop in Gonzales, Texas, Discovery Architectural 
Antiques, is building prefab houses in the 160 square foot range which 
also have a bath, kichenette,  living/ sleeping areas, and even a porch. 
These contain up to 95% recycled materials. I like the Victorian styled 
houses.
http://www.discoverys.com/Tiny%20Texas%20Houses.htm

So, on the surface of it, it looks like there isn't really a minimum 
size standard in the IBC. That doesn't quite answer your question, but 
the existence of these sites inform me that people have looked into the 
question. I just couldn't uncover any definite figures.
The problem you'll probably come across is that municipalities, and even 
small subdivision developments, have minimum size rules that are 
enforced. Part of this is because municipal tax rates are based on the 
appraised value of a house, which in turn is largely size-dependent.

Interestingly, in reading the above book, on pages 72-74, the largest 
"accessory" building you can legally build without a permit, according 
to the IBC, turns out to be 200 square feet of gross floor space. That's 
everything excluding the 2' thick exterior SB walls. However, the 
accessory building  is also defined as one that is secondary to the main 
living premises. Or  something like that.  If you raise the roof a bit 
and put in a sleeping loft, this should not be more than 1/3d the floor 
area of the  part below it.  (You by-pass the rule by calling the loft 
or mezzanine a storage area.) Your storage space could be a tansu-style 
cabinet which could double as steps up to the sleeping loft.
The walls are not part of the livable interior, so you can build about a 
16x16 foot structure (256 square ft total area), all other things being 
equal. This applies only to 1-story detached structures.

There are quite a few sites which discuss "tiny houses," if you google 
for that term, and some books available about them.

Anyhow, I've been quite inspired by all these revelations and will now 
start building stuff to be included in a micro-house and collecting 
stuff to build one from.

Cheers,

Chris Green.