Thursday, November 11, 2010

Tiny House Code Compliance - 120 square feet exemption?


Recently I have been researching some alternative temporary housing for our land in Hotchkiss. I have somewhat intrigued by the so-called Tiny House movement. The proponents advocate living in little houses that are frequently less than 120sf in area. These houses provide full accommodation for living, sleeping, eating, and sanitation within a compact package. Many are constructed on dual axle flat bed trailers to permit portability. Don't like your neighbors? Hitch up and leave.
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There is lot of information on these buildings on the web. Interspersed is a lot of BAD information about code compliance methodologies. This blog is intended to set the record straight.
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The first question is determining if the building code is applicable to the structure or not. It is my opinion that any tiny house built and left on a trailer that is provided with tires and a license plate is not subject to building code oversight. If you are in Colorado, the legal precedent affirming this is Eason v. Town of Erie.
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Trailers constitute the building code dead zone that caused HUD to establish requirements for these factory built "mobile homes" years ago. The feds determined that nobody was paying any attention to these type of structures and decided that rules needed to be made. The old "mobile homes" burned hard and fast. Something needed to be done. I am not sure how the HUD regulations affect owner built "tiny houses" and don't proclaim to be an expert. This is one regulatory agency I try to avoid due to their notorious record for convoluted regulations and interpretations. However, I do believe that the "mobile home" must be at least 40' in length and 320sf in area to fall under their jurisdiction.
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If the house is sited on the ground (no trailer), then the building code comes into play. The International Residential Code regulates one and two family dwellings and their accessory structures. Many proponents cite the permit exclusion provisions for "sheds" that are less than 200sf (120 sf in the 2006 edition) in area. This is not a valid permit exclusion for the typical tiny house.
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The key here is the word "shed". The code states, "One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses...". It is hard to argue that these are mere tool sheds or playhouses when they meet the entire definition of Dwelling and Dwelling Unit contained in the code.
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2009 International Residential Code (IRC) Definitions:
DWELLING. Any building that contains one or two dwelling units used, intended, or designed to be built, used, rented, leased, let or hired out to be occupied, or that are occupied for living purposes.
DWELLING UNIT. A single unit providing complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation.
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One could easily argue that a lack of one of the "permanent provisions" would preclude meeting the definition of "dwelling unit". Substitution of the built-in permanent stove with a plug-in counter top microwave would be one example. Elimination of the bathroom facilities is another.
If it isn't a complete "dwelling unit", then what is it? One could then argue it is a nice playhouse...exempt from building code permit requirements.
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Assuming that all permanent provisions are in place and the local code official makes the determination that the building is a "dwelling unit", the fun begins.
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The IRC prescribes some minimum areas for the dwelling. At least one room must be 120sf in area. All other habitable rooms except the kitchen must be 70sf in area. Minimum room width must be 7'. Minimum ceiling headroom must be 7'-0". The list goes on...and as you can see, so will your tiny house... going on down the road to some locale with no building code. Traditional tiny houses simply cannot comply with the IRC if they are determined to be dwelling units.
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A respondent stated the she thought that it would be possible to make the 120sf minimum area work. That may be possible. I will pick this idea up and explore it in a Part 2 post as a follow up to this discussion.
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Some will wonder why the code has so many restrictive requirements. These provisions go back beyond any memory, probably having their roots in the "tenement codes" first promulgated in places like New York City in the mid-nineteenth century. The intent was to provide for minimum habitability standards for conventional houses. Slum lord provisions, if you will.
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Truth be known, it is unlikely that any studies or analysis was conducted to ascertain that a building is safer or more habitable simply by having a single room with 120sf in area. Unfortunately, those that came up with these standards are no longer around to justify their existence. Old "tried and proven" code lore becomes absolute when the original basis for its inclusion is lost.
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Here is the moral of the story: Always do your homework first. Know the rules before you build or purchase. Understand the loopholes provided by the code and local case law. Query your code official on the requirements prior to bringing your building on the site. Be prepared to surmount some hurdles before enjoying your new-found minimalist venture.

23 comments:

Janice said...

If only one room needs to be 120 sf, and no minimum for bathroom, a one room home with a small bathroom can still comply (total ~140 sf). We need to be creative in the means to separate functions without subdividing the space.

Tom Meyers said...

Janice:
Good plan! Not only do you satisfy the code, but you also put in practice some of the principles of Chistopher Alexander's book "A Pattern Language". Sarah Susanka also advocates this in her "Not So Big House" series.
Tom

Anonymous said...

Tom,
Neat post.
Can you elaborate on the 120sqft limitation? Is this the foundation footprint, the total exterior wall footprint? What about height? how do lofts and "2nd stories" count in the determination of area?
Much appreciated!

Tom Meyers said...

The "building area" definition would be derived from the International Building Code by a reference from the IRC. It is taken from the inside of exterior wall to inside of exterior wall. Make SURE that this corresponds with any amendments for the local jurisdiction. This definition may be modified!!
Height of stories in the IRC is unlimited. This may be regulated via zoning. One may not have more than 3 stories and build under the IRC. The 120sf building exception only allows ONE story! Multiple story buildings of under 120sf in area of any floor would still require a building permit.

Anonymous said...

Tom,
I own some rural land in Garrett Co. Maryland. I checked the County Planning and Permits website and they have a checklist for residential builders. One of the items states:
"Required areas: one habitable room = 150 sq. ft. min. other habitable rooms = 70 sq. ft. min.
(Not less than 7 feet in any horizontal dimension) kitchen = 50 sq. ft. floor area. min."
I am wondering if they have neglected to update the checklist because the website says they are following the 2009 IRC code. I would like to build as small as possible. The new code would save me 80 sq ft. Guess I need to contact the County and find out. Thanks for this interesting and informative blog.
Jim

Tom said...

Tom: What is your take on the Colorado Supreme Court's ruling on Town of Erie vs. Eason, which seems to reverse the appeals court ruling that you mention? http://scholar.google.com/scholar_case?case=8857868468293509251&hl=en&as_sdt=2&as_vis=1&oi=scholarr

Anonymous said...

Thank you so much for this clarification. Our city is slated to adopt the new code some time this year, enabling me to build an accessory structure up to 200 interior sq. ft. in our back yard without a permit.

I'm going to use it for a writing studio--no kitchen, no bathroom. But I wanted to have one-half of the building be tall enough to put a loft in it, as a meditation space, a reading corner, or even a place to sleep on occasion.

There is no restriction on building height that is meaningful to this project, and the total height of this half of the building would be about 15 or 16' tall.

Can I call the loft area an attic and access it with fold down attic stairs and still have the studio be considered an accessory structure?

I will be wiring the building for electricity and will get an electric permit for that. But no plumbing in the building.

I'll use a propane fireplace for heat and have it well insulated as I live in a cold climate.

Anthony Sharp said...

I have read that you don't need a building permit for a basement and was wondering if there was any truthfulness behind that statement. I would really like to build partially underground for heating/ cooling reasons anyways and admire the earthship design. I also recently heard (from a coworker whose neighbor built the "UFO welcome center" in Bowman, SC) that if a structure was build using lag bolts it would be considered "temporary" and thus not require building permits. Any information regarding these statements would be appreciated, and thanks for the great information in your post.

Tom Meyers said...

Anon:
The permit exemption is intended for tool or storage sheds and not really for habitable structures like you intend to build. I see no reason why you shouldn't just go ahead and get a building permit and make it legitimate, unless you are doing something that will be difficult to justify under the code (like build it with straw bales, tires, etc.).
In any case, the code says "one story". An attic is not a story. A mezzanine is not considered a "story". It is a level in the building. To qualify as a mezzanine, make sure that its area is no more than 1/3rd that of the open room below.
Last of all, make sure that you install a smoke alarm (and Carbon Monoxide also since you are heating with fuel gas) if you plan on doing any sleeping in there...even if it is by accident while "working".

Tom

Tom Meyers said...

Anthony:
All you heard is urban legend and none of it is true. There is no magic, silver bullet here. Temporary is the time from being constructed until the court orders demolition. Variable duration in all circumstances!
Tom

Monica Thompson said...

Tom,

Good blog and good answers to the questions. What's the single modification to current building codes that would make the most difference to those who want or need to build tiny houses?

Anonymous said...

I see no reason why you shouldn't just go ahead and get a building permit and make it legitimate,

we want to build it ourselves and not be hassled by all the code restrictions.

if we get a permit and follow codes, we'll need a contractor or at least someone who knows what all the codes are, and then we will not be able to afford to build it.

so, the plan is to stick to under 200 sq. ft, keep it one story, not have a bathroom, and use it as an uninsulated shed for the short term, then convert it later with insulation and sheet rock.

thank you for the tip about the smoke detector and carbon monoxide detector.

Tom Meyers said...

Anon:
The residential code is designed to allow an owner to do his/her own work. It is not intended to promote a specific trade or class of construction professional. I agree that it has gotten large and somewhat complicated. That is the nature of our society and as one member of the IRC committee, have little power to stop that momentum. That is the reason for this blog: To start a discussion on an alternative code that is less urban centric and more open to alternative construction. I agree with the general tone of the comments that the code has become excessive in its regulations. It is really designed for the nonintuitive, uninvolved, and marginally responsible home dweller. Therefore, it doesn't always work well for those with expectations and knowledge that are contrary to the urban norm.

If you read my other entries, I discuss the code excesses and suggest the creation of an alternative code that is very simple and more performance driven. I may end up developing it for one of my clients (Solar Decathlon). In the meantime, you will note that I recently purchased land in a county with no adopted building code. That says something.

Noah said...

Hi Tom,
Great site!
I'm renovating an old 300sf building in my backyard that is designated on the tax record as a "living quarters". It has a toilet, sink, gas heat, water heater, kitchen sink, and AC.

I want to raise the 7' flat roof to 10' and 12' sloped, add a shower, and put loft space above the bathroom.

If the loft space is over 70sf but the ceiling above it is below 5' will it still be considered "non-habitable"? In other words, how many of the habitability criteria must be met and in what combination? And will it matter if that space happens to have hardwood flooring and a queen sized bed in it?

Thanks,
Noah

Anonymous said...

Hi Tom
Thank you for your insight on codes and making tiny houses/ tiny house trailers code compliant. It's a much needed glimpse of reality.

Please clarify: Does the code allow a combined kitchen/bedroom? (120 s.ft. minimum interior floor area total?)

Or does the code require a 120 s.ft. bedroom AND a 70 s.ft. kitchen room? (mimimum interior floor area total 190 s.ft.?)

Does the code allow a "wet" bath where the open area in front of a toilet and sink serves as the drainage area for a shower? If yes, is the area of the sink or the toilet fixtures subtracted from the "shower" area of 30 in. by 30 in.? (Could you have a "shower" floor area of 24 in. by 30 in. between the sink and toilet fixtures. Also, are over the toilet sinks or toilet tank sinks code compliant as a sink fixture in the bathroom?

Tom Meyers said...

As to the question of whether a house may have a combined kitchen and living area, the answer is yes. The kitchen minimum area was deleted in the IRC. I did that years ago, back when it was 50sf I believe. We just did similar for residential under the IBC (commercial). There is no reason one cannot combine the two into the 120sf if they are open to one another.


Combined shower and toilet/sink areas are problematic. The big code issue is the prohibition of electrical outlets and switches in showers and bathtub locations. When all is combined, it is hard to tell when the mandatory 20amp outlet is in or out of the shower. Been down that road with a number of these in previous Solar Decathlon events.
I would say that the 30x30 is clear space for maneuvering. Therefore, one would not be permitted to have other fixtures encroach. Be aware of an exception that increases the area to 1300 square inches but permits a 25" width in one direction.
I have showered in 24x24 compartments in Italy. Not very comfortable at my shoulder level. Hard to wash soap out of my hair when I couldn't really raise my arms!

Anonymous said...

God Bless Tom Meyers, I want a Tiny House but I want to build it in compliance with the Building Code. I've spent MONTHS reading books and blogs that talk about AVOIDANCE and ways to get around the ordinances in place for building. Living minimally isn't about being illegal it's about simplicity. Thank you for giving us a place to find great information for people like me.

Lee said...

Tom, thank you for all that you are doing regarding building codes and also giving advice here.

I'm also interested in building a tiny home as a primary dwelling on an unrestricted lot within the city of Austin, TX. I've been reading the IRC and the IBC. What I've noticed is that the IBC has a minimum set for "Efficiency Dwelling units". The minimum is 220 net sq ft of living area which does not include kitchen cabinets/appliances (from what I've comprehended). That aslo doesn't include the mandatory closet or separate bathroom. IBC 1204.8

Now, on the other hand it seems that one could almost build smaller by building a 1 bedroom home, which may not be considered an "efficiency dwelling". So, is a small stand alone residence that shaped like a house considered an efficiency dwelling, or is this just a minimum to make real estate investors stick to regarding multifamily property construction?

Lee said...

Tom, thank you for all that you are doing regarding building codes and also giving advice here.

I'm also interested in building a tiny home as a primary dwelling on an unrestricted lot within the city of Austin, TX. I've been reading the IRC and the IBC. What I've noticed is that the IBC has a minimum set for "Efficiency Dwelling units". The minimum is 220 net sq ft of living area which does not include kitchen cabinets/appliances (from what I've comprehended). That aslo doesn't include the mandatory closet or separate bathroom. IBC 1204.8

Now, on the other hand it seems that one could almost build smaller by building a 1 bedroom home, which may not be considered an "efficiency dwelling". So, is a small stand alone residence that shaped like a house considered an efficiency dwelling, or is this just a minimum to make real estate investors stick to regarding multifamily property construction?

Anonymous said...

Most of the minimum size requirements did originate with urban "tenement" codes. If you're ever in NYC a visit to the Tenement Museum will show you why they were written. Without them property owners would subdivide space into a warren of tiny spaces. I've seen many such illegal dwelings in NYC. You'd be better off living in a cave, as at least the risk of fire would be smaller. Every few years one of these illegally subdivided dwellings catches fire and the results are not pretty since proper egress is nonexistent and fire caodes are completely ignored.

The 30"x30" shower dimension is usually explained as giving sufficient room to manuever if the water suddenyl comes out scalding. If you've ever been on a small boat with a 24"x24" stall, you'll quickly relaize the validity, even if it's not the original reason for the code.

Anonymous said...

Great site U have here !

I have read over many of the posted comments on codes, etc. and here is my take on it.

I am a urban guy and I love the idea of "tiny" houses and will build one this year, but here are the realities of how to legally deal with "building codes" in regards to tiny homes:

1. If U live in a big urban metro area like Chicago, Miami, or L.A., U are in a metro that is over regulated and your dreams of a tiny home are slim to none.....IF U want to follow the so called local building regs.

2. In the USA 75% of the population lives on only 2% of the available land. That 2% is over regulated out of the ying yang.

3. Where the "tiny house" action is...is where the 25% of the population lives on the 98% available land. Which is mostly rural areas.........off grid !

4. If U wanna go tiny or even big and have less hassle from "The Man", which is the local code enforcement people.....get out of Dodge and where there are others who already live the way U want to live.

Once again, I come from a urban environment, but I love the idea of debt free/mortgage free living over a lifestyle of "stuff" and serving a 30 year prison sentence called a "mortgage". So I go to where the REAL tiny house action is.........and that ain't place near a major urban area.

Anonymous said...

I think looking at all of this, it would be easier if you want tiny living to get an RV. Of course I understand that appeal of living in a house you designed yourself, but in many places living in an RV would be a lot less hassle, and many of those have all the amenities you need. If I needed a portable home, I think I may prioritize a motorhome over building one of these tiny homes, given I can find one for a good price, with a good financing plan. Right now our 850 sq foot apartment feels to big for me, I want to go smaller to a studio or 1 bedroom both of which is 500 sq ft. Overall, this tiny house movement fascinates me, and I like knowing about the building codes and what is and is not allowed. Thank you for this information.

Unknown said...

Very interesting material, thanks!
I am wondering-
What if you built a 120 sf. building without any cooking, sleeping, or bath areas, then positioned a custom-made "trailer" (built on axles) beside it that contained these?
Also- am I correct in assuming that there is no restriction to building a 500 sf porch/deck area on the said 120 sf structure?

Darrell Williams