Category Archives: Advocacy for Friendly Codes

10/14 Coconino County, Arizona invites the public to discuss draft of tiny house zoning & coding rules

Coconino County, AZ community development logoCoconino County Community Development is hosting an open house on the draft permitting process for tiny houses on Tuesday, Oct. 18. The event is open to the public to learn about the draft policy and to provide feedback before it is finalized later this month.

The open house will be at Willow Bend Environmental Education Center, 703 E. Sawmill Road from 3:30 to 5 p.m.

Source for the event:

Here is the draft (note: these rules have not been yet adopted):

Permitting Regulations for Tiny Houses in Coconino County
Draft- August 19, 2016

Definition: Coconino County Community Development defines a Tiny House as a house smaller than 400 square feet; it can be site-built, partially site-built, or on an approved trailer. Houses shall not be smaller than 200 square feet.

Zoning Code Requirements for Tiny Houses:

  • Site built tiny houses built on an approved foundation system shall be permitted in zones
    allowing detached single family dwellings; must meet Community Development regulations for Tiny Houses
  • Tiny houses built on trailers, where the suspension/axle components have been removed and the chassis permanently attached on an approved foundation shall be permitted in zones allowing detached single family dwellings; must meet Community Development regulations for Tiny Houses
  • Tiny houses on mobile chassis where the suspension/axle components remain are considered semi-permanent and the chassis shall be attached on an approved foundation system, and shall be permitted in zones allowing for manufactured and mobile homes; must meet Community Development regulations for Tiny Houses
  • Tiny houses licensed as Travel Vehicles by the State of Arizona are non-permanent housing and must be self-contained, these shall be permitted for uses similar to recreation vehicles; these homes fall under ADOT jurisdiction
  • Site built tiny houses or tiny houses on trailers where the suspension/axle components have
    been removed and the chassis permanently attached on an approved foundation, and meeting all other multifamily zoning and Community Development Tiny House requirements, shall be permitted in multifamily zoning
  • Site built tiny houses, or tiny houses on trailers where the suspension/axle components have been removed and the chassis permanently attached on an approved foundation, and meeting all other Accessory Dwelling Unit zoning and Community Development Tiny House
    requirements, shall be permitted in zones allowing for Accessory Dwelling Units.

Building Code Requirements for Tiny Houses:

  • Tiny houses shall be built and inspected in accordance with the Coconino County adopted
    building code and ordinance.
  • The house can be partially or entirely built on-site or off-site. If built off-site, it needs to have been inspected and approved by a recognized agency approved by the Building Official. All Tiny Houses on Wheels (THOWs) that are built off-site and brought to Coconino County as a dwelling unit will require a plan review and special inspection by Coconino County Community Development to ensure the structural and life safety aspects of the THOW. The County can request additional remodel permits, inspections and engineering of off-site THOWs that have not been inspected and certified by another jurisdiction or third party agency-on a case by case bases.
  • The County has made the following building code adjustments to accommodate tiny houses:
    1. Minimum room dimension is 6’6” with no room smaller than 65 square feet, excluding
      storage areas and bathrooms
    2. Ceiling height is 6’4” in open livable areas, creating a non-obstructed path for egress and
    3. Egress and ingress must be provided in sleeping and living areas
    4. Lofts built as storage shall not be permitted as bedrooms, unless meeting ceiling height and egress/ingress requirements
    5. Bathroom and kitchen required, clearance in the front of the toilet needs to be no less than 15” from center of toilet to wall or cabinets
    6. Ladders/lapiers may replace stairways to loft areas (must have uniform run and rises,
      provide stair or ladder detail on plans)
    7. Loft areas used for storage may have reduced fall protection
    8. Number of electrical circuits may be reduced to reflect loads
    9. A minimum of 60 amp electric panel required
    10. Energy Code Concessions: R-15 minimum in framed floors, ceiling insulation and wall
  • Tiny houses built on trailers will need to a have Manufacturer’s Statement of Origin (MSO), or a Manufacturer’s Certificate of Origin (MCO), or be registered with the Department of Motor Vehicle (DMV). Documentation must show the load capacity for the trailer. Before a Certificate of Occupancy can be issued, documentation must be provided to Coconino County Community Development verifying the load of the tiny house is within the load capacity of the trailer.
  • A Certificate of Occupancy will only be issued for tiny houses set on permanent foundations. If the home is removed, the Certificate of Occupancy is no longer valid for the mobile tiny home on wheels. If the tiny home is re-set on a permanent foundation within Coconino County, a foundation permit and special inspection of the tiny house shall be required to obtain a new Certificate of Occupancy.

Wastewater Requirements:

  • Tiny houses set on a permanent foundation will be required to have a wastewater system sized to accommodate the occupancy and fixture count.
  • Tiny houses used as RVs and sited at an RV park must be fully self-contained
  • Compost toilets need to meet ADEQ approved list
  • Graywater needs to be approved for permanently sited tiny houses, to ensure no issues with wastewater system function, as well as environmental considerations like high ground water, wells, and permeability of soils.
  • Tiny Houses on Wheels (THOWs) can include plumbing for graywater-but if permanently sited, the THOWs must go through an approval process

Engineering Division Requirements:

  • Permanently sited Tiny Homes need to meet all Engineering requirements, including drainage, road encroachments, floodplain and roads.

Source for draft code:

Draft code document: Draft-Coconino County Permitting Regulations for Tiny Houses.pdf

Walsenburg, Colorado modifies building code to be tiny house friendly

Walsenburg, Colorado passed amendments to the 2015 IRC to be more tiny house friendly for homes on foundations. They waived minimum room areas and stairway regulations and reduced the requirement for exit door width: Walsenburg Colorado Ordinance No. 1092

Zoning regulations were made tiny house friendly in 2014:

Suggested changes to Virginia’s Uniform Statewide Building Code for tiny houses on foundations

Here are changes suggested by Thom Stanton to accommodate tiny houses on foundations in Virginia:

Suggested Changes to the IRC

by Thom Stanton, American Tiny House Association’s Virginia State Chapter Leader

Thom defines a small house as being not more than 500 sq ft. and suggests these changes:

Section R327, Small Houses

  1. Access to the basements, underfloor areas and lofts shall be by means of alternating tread devices, ladders, or any means that complies with Section R311.
  2. The minimum floor areas of Section R304 shall not apply.
  3. The minimum ceiling height requirements of Section R305 shall not apply.
  4. Lofts used as sleeping areas shall not be required to comply with Section R310 provided that the loft opens to a floor containing an emergency escape and rescue opening.
  5. Basements and underfloor areas shall not be required to comply with Section R310 provided that the
  6. basement or underfloor area does not contain sleeping rooms.
  7. The minimum door sizes of Section R311.2 shall not apply.
  8. The hallway width requirements of Section R311.6 shall not apply.
  9. The guard requirements of Section R312 shall not apply to lofts.
  10. The automatic fire sprinkler requirements of Section R313 shall not apply.


Model Code for Accessory Dwelling Units

From the editors of, what follows is a proposal for a model zoning code that ensures ADUs are small and discreet, while also providing enough latitude in their creation that they actually get built.

Accessory Dwelling Unit Model Code

1. Purpose. Accessory dwelling units are allowed in certain situations to:

a. Create new housing units while respecting the look and scale of single-dwelling development;
b. Support more efficient use of existing housing stock and infrastructure;
c. Offer environmentally friendly housing choices with less average space per person and smaller associated carbon footprints;
d. Provide housing that responds to changing family needs, smaller households, and increasing housing costs; and
e. Provide accessible housing for seniors and persons with disabilities.

2. Definition. An accessory dwelling unit (ADU) is a smaller, secondary home on the same lot as a primary dwelling. ADUs are independently habitable and provide the basic requirements of shelter, heating, cooking, and sanitation. There are two types of ADUs:

a. Garden cottages are detached structures. Examples include converted garages or new construction.
b. Accessory suites are attached to or part of the primary dwelling. Examples include converted living space, attached garages, basements or attics; additions; or a combination thereof.

Comment: Alternative name possibilities are listed here.

3. Eligibility. An ADU may be added to a house on any residentially zoned lot.

Comment: Some codes restrict ADUs to certain zoning designations, lot sizes, and/or geographic areas within the jurisdiction. Such restrictions significantly constrain the number of eligible properties and suppress the number of ADUs that can (legally) get built under the code.

4. Number. One ADU is permitted per residentially zoned lot.

Comment: Vancouver, BC allows both a garden cottage and an accessory suite on a residentially zoned lot. This has not been tested to our knowledge in the US, but seems like a promising idea.

Possible additional language: “Where more than one house is allowed on a single lot through a planned development process at the same or similar density as would be allowed by subdivision, one ADU is permitted per house.”

5. Creation. An ADU may be created through new construction, conversion of an existing structure, addition to an existing structure, or conversion of a qualifying existing house to a garden cottage while simultaneously constructing a new primary dwelling on the site.

Comment: It’s not uncommon for jurisdictions to limit ADUs to certain types (ie. internal or detached) or to properties where the primary dwelling is of a certain age. Such restrictions constrain ADU development, since property-specific conditions (ie. existence of basement, size of lot) often limit the type of ADU that can be created.

6. Density. ADUs are exempt from the residential density standards of this code.

7. Approval. Applications for ADUs must meet the following criteria. Requests to adjust these standards are handled through a [ ] process.

a. The applicant must demonstrate that the ADU complies with all development and design standards of this section.
b. The applicant must demonstrate that the proposed modifications comply with applicable building and fire safety codes

Comment: It’s appropriate to require a land use process for adjustments to code standards. But when discretionary land use processes or conditional use permits are required for every ADU, this becomes a significant barrier to ADU development. Land use fees and process time, neighbor notification requirements, and approval unpredictability make an already expensive and challenging project even less accessible to owner-builders (see Martin Brown’s post on barriers to ADU development). In practice, many prospective ADU builders never take the first step if the code doesn’t support as-of-right development.

8. Occupancy and Use. Occupancy and use standards for an ADU shall be the same as those applicable to a primary dwelling on the same site.

Comment: ADU codes that place more restrictions on tenure (ownership vs. rental), short-term rental, affordability and/or home business than would apply to a primary dwelling on the same lot result in less ADU construction. Owner-occupancy requirements make properties with ADUs unsuitable for income-based valuation by appraisers, constraining their value and making them more difficult to finance. Affordable housing restrictions on ADUs sound appealing, except that deed restrictions and tenant income screenings are (unsurprisingly) obstacles for mom-and-pop landlords (fortunately, ADUs provide a surprising amount of market-based affordable housing without subsidy or use restriction). An in-depth discussion of how these restrictions limit ADU development is provided in ADUs and Don’ts.

9. Design. Design standards for ADUs are stated in this section. If not addressed in this section, base zone development standards apply.

a. All ADUs (accessory suites and garden cottages) must meet the following requirements:

i. Size. An ADU may be no more than 800 square feet or the size of the primary dwelling, whichever is less.

Comment: In addition to a total size cap (typically 600sf – 1,000sf), some codes also cap ADUs to a certain percentage of the size of the primary dwelling. Note that such constraints effectively act as a small house penalty: limiting the size of ADUs on lots where the primary dwelling is already fairly small, but having no impact when the primary dwelling is big.

Possible additional language: “The size of a basement accessory suite occupying the entire footprint of a home built prior to ____ may be up to [1,000 – 1,200] square feet.”

ii. Parking. No additional parking is required for an ADU. Existing required parking for the primary dwelling must be maintained or replaced on-site.

Comment: Parking requirements for ADUs can significantly increase costs and remove lots from consideration where it is impractical to add a parking space. A major survey of Oregon ADUs revealed no evidence that ADUs contribute to neighborhood parking problems.

b. Accessory suites must meet the following additional requirements:

i. Location of entrances. Only one entrance may be located on the facade of the primary dwelling facing the street, unless the primary dwelling contained additional entrances before the accessory suite was created. An exception to this regulation is entrances that do not have access from the ground such as entrances from balconies or decks.
ii. Exterior stairs. Fire escapes or exterior stairs for access to an upper level accessory suite shall not be located on the front of the primary dwelling.

c. Garden cottages must meet the following additional requirements:

i. Height. The maximum height allowed for a garden cottage is the lesser of [20-25] feet or the height of the primary dwelling.

Comment: Definitions of height vary from code to code. If they go to the peak of the roof, consider a higher height limit. If they go to the average height of the roof, consider a lower height limit.

ii. Building setbacks. Garden cottages must be located at least six feet behind the primary dwelling, unless the garden cottage is in an existing detached structure that does not meet this standard.
iii. Building coverage. The building coverage of a garden cottage may not be larger than the building coverage of the primary dwelling.
iv. Yard setbacks. No portion of an existing building that encroaches within a required yard setback may be converted to or used as a garden cottage unless the building complies with setback exemptions (ie. for garages, properties abutting alleys…) available elsewhere in the code.

Miscellaneous Topics

Design Compatibility
Some cities, including Seattle, WA, Vancouver, BC, and Eugene, OR, don’t have any special requirements that ADUs match the exterior appearance of the primary dwelling. There’s a good case for this, especially since ADUs represent a sizable investment and builders have plenty of market incentive to make them look appealing and appropriate for the neighborhood. Design compatibility requirements often single out ADUs while offering no such constraints on other types of accessory structures (ie. garages, art studios…). For these reasons, compatibility guidelines are not included in this model code.

However, since design compatibility requirements are quite common and sometimes help build public acceptance for ADUs, following is some implementing language that could be appended to Sections 9.b and 9.d:

(Add to Section 9.a. – All ADUs)

iii. Exterior finish materials. Exterior finish materials must visually match in type, size and placement, the exterior finish materials of the primary dwelling.
iv. Roof pitch. The roof pitch must be the same as the predominant roof pitch of the primary dwelling.
v. Windows. If the street-facing façade of the ADU is visible from the street, its windows must match, in proportion and orientation, the windows of the primary dwelling.
vi. Eaves. If the primary dwelling has eaves, the ADU must have eaves that project the same distance from the building. If the primary dwelling does not have eaves, no eaves are required for the ADU.

(Add to Section 9.c. – Garden cottages)

v. Exemptions. Garden cottages are eligible for either of the following exemptions:

1. Design compatibility. Exceptions to Sections 9.a.iii.-vi. are granted for garden cottages that:

a. Are under 500 square feet and under 18’ average height, or
b. Meet Community Design Standards, defined elsewhere in the code.

Comment: These exceptions provide design latitude for smaller garden cottages and an alternative path in cases where the primary dwelling is ugly and/or out of character with neighboring homes.

2. Alteration. If a garden cottage is proposed for an existing detached accessory structure that does not meet one or more of the standards of Sections 9.a.iii.-vi., the structure is exempt from the standard(s) it does not meet. Alterations that would move the structure out of conformance with standards it does meet are not allowed. If any floor area is added to a detached accessory structure, the entire structure must meet the standards of Sections 9.a.iii.-vi.

Impact Fees
Although not typically included in zoning code language, the way building permits and impact fees (sometimes called ‘system development charges’) are calculated for ADUs can have a big effect on how many get built. This is especially true if such fees represent a significant percentage of the total project cost (particularly likely with relatively inexpensive ADU conversions). Finally, high fees can steer ADU development ‘under the radar screen,’ where there’s no permitting or inspection at all – and a greater likelihood of dangerous life/safety conditions for residents.

It’s common for jurisdictions to charge reduced impact fees for ADUs. Portland’s decision in 2010 to waive impact fees on ADUs to meet public policy goals played a significant role in the subsequent increase in ADU development. Depending on municipal policy goals, there may well be a case for setting ADU fees below what would be charged for a standard single family home or dropping them altogether

Prepared by Eli Spevak, with special thanks to co-editors Martin Brown and Kol Peterson, Jordan Palmeri, and Ben Schonberger for their assistance with this project. In assembling this code, we borrowed language and structure from multiple ADU codes including Portland, OR and Grants Pass, OR.


A Legal Path for Tiny Homes

Eli Spevak of Orange Splot LLC is proposing this legal path for tiny homes in Portland, Oregon.

Proposal. Create a legal path for the occupancy of small accessory structures or homes-on-wheels that meet sanitary and life safety requirements drawn from Portland’s Property Maintenance code and Oregon Landlord-Tenant law. Regulation of the occupancy of tiny homes would be accomplished through annual inspections to ensure they continue to meet standards over time.

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Motivation. This proposal would legalize new forms of small, safe, low-cost, environmentally friendly, and discreet housing that further important city goals, including:

Providing affordable rental opportunities for homeless and/or low-income residents requiring little or no public subsidy;
Supporting extended family and other community living situations that don’t always fit well within traditional single family homes;
Generating construction jobs to build tiny homes; and
Creating opportunities for people to live in the City of Portland with much smaller environmental footprints than is achievable through more traditional residential development forms.
Context: Building vs. Property Maintenance Codes. City building codes must be met at the time a home is built. Once constructed, the applicable code becomes the property maintenance code, which focuses on performance measures (ie. ability to heat them, ingress/egress, access to hot and cold water…) that can be evaluated without opening up and inspecting hidden parts of the building’s structure and envelop. The vast majority of homes in Portland, including nearly every stately old home in close-in neighborhoods, would not meet today’s building codes. Yet they are legally habitable because they comply with the property maintenance code. This proposal would allow the habitation of new and converted structures that meet the property maintenance code and other standards, but not necessarily today’s building code.

1. Small Accessory Structures. In residential zones within the City of Portland, building code allows the construction of accessory structures up to 200 square feet in size and up to 10’ tall without building permits. Examples include garden sheds, play houses, meditation rooms, dog houses and saunas. Electricity and plumbing can legally be extended to these buildings so long as the installer obtains trade permits and gets the work inspected. The building code does not, however, allow such buildings to be used for ‘habitable’ purposes. This proposal would allow for the habitation of these structures if they meet specific performance standards. It would not extend to larger accessory structures for which building permits are required.

2. Homes on Wheels. Residential zones also allow for the parking of vehicles, including homes on wheels. These are not technically buildings, so are not covered by the building code. They can legally be used for many of the same purposes described above for small accessory structures. But there are currently some provisions in the property maintenance code that prohibit them from being used for ‘habitable’ purposes. This proposal would create an allowance within the maintenance code for the habitation of these structures if they meet specific performance standards.

Permitting Mechanism. Either of the above structure types could be granted a temporary certificate of occupancy (“TCO”) by meeting specific conditions of approval. TCOs would be good for one year and renewable if an annual inspection determines that the conditions of approval are still being met. As long as the TCO is in effect, the structure could be legally occupied as a residence. It would be the property owner’s responsibility to request and pay for these inspections.

Conditions of Approval. Following is a sample list of standards, plucked in part from Portland’s Property Maintenance code, Zoning Code, Building Code, and Oregon Landlord-Tenant law:
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