Voluntary Code of Practice

The proliferation of chattel shelter: shipping containers placed on land for storage and human activities, and the increased popularity of tiny homes on wheels, caught out councils whose planning and building consent rules were written for structures and buildings, not chattel. The issue generally arises when there is a clash of cultures. Persons living in “nice” neighbourhoods do not like the way their neighbours live and complain to council. Lacking proper tools some councils take an aggressive approach, asserting the units are buildings, and looking to central government for support. While the officials say they issue abatement notices in the interest of health and safety, the headlines read “Neighbours rat out ‘ugly’ tiny homes“.

MHA proposes that its members establish a voluntary code of practice that ensures consistently high quality products that provide for health and safety and hopefully a sensitivity to visual amenity. Below is a first draft. If accepted by officials, this would remain operative until formal legislation and regulation replaced it.


Structure” as used in Section 8 of the Building Act 2004 has the same meaning as in the Resource Management Act 1991 Section 2(1)

Building” in the National Planning Standards has the same meaning as in the Building Act 2004 Section 8.

Mobile Trailer Homes exceeding 2.55 m wide are indivisible specialist overdimension trailers under Land Transport Rule 41001 6.6(1)

Chattel is personal property as defined in common law.

Real Estate is real property as defined in common law.

Shelter means any place of habitation or occupation  by people, animals, machinery or chattel that provides privacy and protection from the elements, danger or other hostile potential.

Chattel Shelter means any form of shelter that is personal property, not real property. This means property that is not fixed to land and not annexed to title to the allotment.

Volunteer Code of Practice (VCP) is a proposed agreement between the Crown and the private sector that sets out agreed upon standards by which certain forms of chattel structure are agreed to not be considered buildings or structures, provided the terms and conditions of the VCP are adhered to for each unit certified under the agreement.

Chattel Shelter Unit (mobile home) refers to any form of chattel structure that is covered under the proposed Volunteer Code of Practice. This includes mobile homes (any mobile home including on skids and on wheels) and mobile trailer homes (on wheels)

Fixed to land has the same meaning as in common law, but for clarity does not include anything that is solely held by gravity, anchored with guy lines (removable cables, chains, ropes, etc.) to prevent movement in high wind, or anything that is connected to utilities (such as water, wastewater, gas or electricity) provided such connection and disconnection may lawfully be done by any person and not require the services of a licensed practitioner.

Construction means the art of building structures on site, using raw materials, such as lengths of timber and concrete, and approved components such as premanufactured lining, cladding, roofing and joinery to build physical structures that are regulated in New Zealand under the Building Act 2004 and its respective building codes, and are built on site by Licensed Building Practitioners with staged inspections by Building Consent Authorities. Construction generally involves a diffusion of liability as numerous parties are contracted to provide design, certification, product and labour, that all come together at the site where the structure is to be fixed to land.

Manufacturing means the science of fabricating in factories in which a specific design, that may include prescribed features and options, are assembled by factory workers and automated machines to turn raw materials and prefabricated components into finished goods for sale. Manufacturing generally involves a single-party holding all liability where finished goods are made in a single location and then shipped to the final customer located somewhere else.

Immovable means fixed to land in a form that cannot be moved without pulling down or taking apart. In structures immovable generally means fixed to a foundation or pile embedded in the earth.

Movable  means that part of a structure that moves while the structure remains fixed to land, as, for instance, a windmill or turntable moving about a pivot,  or a floating pontoon fixed to a pier where the pontoon moves up and down with the tide.

Mobile means chattel not fixed to land that is designed to be moved from one allotment to another. A prison bunk bed bolted to the floor and wall is immovable. A hospital bed with cranks is movable . A wheelchair is mobile . A building that secures a building consent to be removed as a single unit and towed on public roads to another allotment ceases to be real estate when it becomes mobile, even though it was not designed to be mobile, and it reverts to real estate when it is subsequently fixed to land at the new allotment, but if parked on a house removal company’s property awaiting resale is not annexed to title of that land.

Permanent Land Use means a change to the use of land that is not easily reversible, such as  subdividing into allotments and constructing foundations and structures that cannot be removed without being taken down , taken apart or demolished

Reversible Land Use means a change to the use of land that is easily reversible because the land is not subdivided and the land use can be reverted by physical removal of any chattel shelter.

Mobile Home means any  manufactured chattel shelter that is a motor vehicle (including a trailer) as defined in section 2(1) of the Land Transport Act 1998 provided it is not fixed to land.

Mobile Trailer Home means any manufactured mobile home intended for permanent occupation by people including ancillary storage of chattel that is drawn by mechanical power, that is no larger than a Category Three  Overdimension Requirements as set out in Schedule 6 of Land Transport Rule Vehicle Dimensions and Mass 2016 Rule 41001, that is designed to be lawfully towed on public highways, that is not fixed to land.

Tiny Homes on Wheels (THOW) is a recent term for mobile trailer homes popularised by Millennials. Most begin as bespoke construction by DIY individuals, some of whom make a business out of it, building for others, and eventually moving into the mobile home business in a factory. For the purpose of clarity, in this document, THOW will refer to bespoke mobile trailer homes, not manufactured or prefabricated.

Prefabricated  Single Floor Module means shelter that is manufactured in a factory and delivered to an allotment fully made intended to rest on skids if chattel shelter not fixed to land, or fixed to a foundation or piles if intended to be a structure fixed to land. 

Converted Shipping Container means a metal box manufactured for international shipping on ships, rail and trucks that have been converted to chattel shelter.

Flat Pack Shelter means premanufactured shelter made in a factory and packed for shipping, usually in an international shipping container for assembly or reassembly either on site or at a domestic assembly plant that may either be a structure or chattel shelter, depending on whether it is fixed to land or not.

PPVC: Prefabricated Prefinished Volumetric Construction is a building construction method whereby free-standing 3-dimensional modules are completed with internal finishes, fixtures and fittings in an off-site fabrication facility, before it is delivered and installed on-site as structures fixed to ground.


Voluntary Code of Practice

Customer Concerns: NZ is suffering from an affordable housing crisis where society is polarising between those who can afford the high prices of homes caused by a convergence of pecuniary interest adding to the cost of land, cost of consent, cost of compliance and cost of construction. Attempts  by central government to solve the crisis, such as KiwiBuild, have not made a significant difference.

The core concern of the have-not customers is price. Every dollar that is added to the cost ultimately is paid by the customer. At present, the cost of chattel shelter, most notably mobile trailer homes, is about $60,000 or lease at $250/week for a 8m x 3m one-two bedroom self contained living unit with kitchen, bathroom and lounge, making this class of housing the most affordable warm, dry, safe and durable housing in NZ. At present, chattel housing does not attract the accretion of excess costs inherent with buildings. The customer concern is that any new rules or standards or compliance regimes add minimal costs to the cost of affordable shelter and further do not involve regulatory processes that cause stress and uncertainty due to the time and requirements therein.

Industry Concerns: For decades, New Zealand has had a very quiet chattel shelter industry, most notably manufacturing and/or importing mobile trailer homes that have sold and leased affordable housing with no interference from local government. Tens of thousands of such units are found throughout New Zealand, some premanufactured to a high standard, others DIY converted buses or bespoke tiny homes on wheels. The industry needs certainty that the products it makes and sells/leases are accepted by the authorities, and during this transitional phase where regulations have not caught up with product offerings, that a voluntary code of practice can be put in place that addresses council, customer and industry concern.

In addition to design, the industry needs assurance the units may be lawfully transported on public roads. While some manufacturers make 2.5m wide living units, larger widths are better for people, and Land Transport Rule 41001 makes provision for such transport.  Towing behind a ute costs substantially less than loading onto a flatbed truck, a cost ultimately borne by the customer. This mobility has a second concern in that it means units may be relocated from one council territory to another annually or even seasonably. Units may be manufactured in North Island, and delivered to South Island. For this reason an national regime is important where there is a single government agency or department that manages the units, with a real-time interface so councils know at all times how many units are in their jurisdiction, where they are and contact details.

Council Concerns: With the leaking house crisis that was an outcome of the deficiencies in the Building Act 1991, law changes and court cases found that territorial authorities held both joint and several liability that fell to them when the private parties went into liquidation, and political liability because the people blamed them for the failure. Political liability is a matter of perception, not law, but perception is powerful in politics. Further, under the political philosophy of user-pays and the limits on revenue sources placed on territorial authorities, councils jealously guard their potential source of income, including fees, rates and penalties. Finally, councils are charged with defending the public interest when private pecuniary interest becomes predatory. The council concerns that must be addressed include:

  • Liability: When council issues a building consent, they take on joint and several liability. While a high court declaration that chattel shelter is not a structure would relieve the council of legal liability, if something goes wrong, the political backlash falls on them. Accordingly, any voluntary code of practice must give reasonable protection that lowers the risk of backlash to what councils regard as an acceptable level.
  • Fairness: The public must see that rules for chattel shelter are fair and not a loophole to avoid the regulatory regime that applies to buildings and structures. 
  • Misrepresentation: The initial buyer purchases the unit as chattel for, say $60,000, but several resales later, the owner misrepresents the unit as a building worth, say $200,000. Council needs assurance that any simple inspection of the physical premises would make clear the unit is chattel, not annexed to title
  • RMA Effects: The RMA concerns itself with land, air and water, with land including structures, defined by the RMA as fixed to land. Recent attempts by MFE to deal with chattel shelter not fixed to land by changing the meaning of the word building create more problems than they solve, especially because they invented a new term called physical construction without considering that the target of their concern are manufactured, not constructed. Never-the-less, even if the shelter unit is excluded from the Act, its effects are real and should not require amending district/unitary plans to ensure they are controlled.
  • Utility Services Effects: More occupied bedrooms means more people using pipes and roads. At one point the services reach maximum and council must spend significant money upgrading capacity. While this may not be a significant issue in real impact, and there are alternative systems if councils are open to them, this remains a legitimate concern
  • Safe, warm, dry and durable: The Building Act concerns itself with ensuring peoples homes and work places are fit for purpose because they are large, complex structures beyond the skill of ordinary people to evaluate, and which generally remain in place for no less than 50 years. Councils need assurance that small, simple chattel shelter, while less difficult to evaluate, is fit for purpose and remains so for its projected life. Having said this, these smaller, simpler designs do not need to meet a 50-year performance standard, because everything in them is accessible within a day.
  • Typology: Further Council needs clear typology for each unit that it agrees to permit. This is similar to CodeMark but without the red tape inherent in CodeMark.
  • Cost recovery: Councils operate their planning departments and building consent authorities on a self-funding basis, thus they may regard the installation of chattel shelter as lost revenue. Further, they fund their infrastructure with developer charges and they fund ongoing services with rates. If a unit is not a building, there is no mechanism for cost recovery. This concern is more nuanced however. It should be understood that most of the people occupying such shelter (except for those used in the tourism industry) are NZ’s most vulnerable, the ones who otherwise might be provided with council low-income housing. It may good policy to have ratepayers subsidise this lowest-income housing by not pursuing charges. Further, the valuation of a $60,000 unit is unlikely to result in a significant rates loss. 
  • US-Style Trailer Parks: The media furthers the view of trailer house trash as poverty camps that foster crime, domestic violence, substance abuse and other anti-social behaviour. For this reason, council trade associations lobby central government to not let them proliferate in New Zealand. MHA agrees. However, NZ has another, much more desirable and sustainable model known as the pre-colonial Kainga. Maori today will take visitors on tours of ancestral land and point out the sites where wharepuni used to stand (see https://natlib.govt.nz/records/22844562 for an example). Traditional kainga had more than the whare nui (the large decorated meeting house familiar today) and the whare kai, where tangata whenua hosted manuhiri. This model is worthy of replication for all the people of New Zealand. In it, the principles of a cohesive community are paramount, where the wharepuni are a delivery mechanism, not an end in themselves. 


How to align these three sets of concerns now on an interim basis until law and regulation catches up.

MHA proposes the following:

  1. MHA representing the industry, two large councils, one iwi group and MBIE or Kainga Ora agree to ask the High Court for a declaration on the meaning of building and structure and other issues lawyers recommend.
  2. MHA to work with the affected parties (customer, council, crown and industry) to draft a Voluntary Code of Practice that addresses the concerns of the affected parties with incentives for all to voluntarily comply.
  3. Clarification is sought on the current law, codes, standards and other statutory documents.
  4. Focus begins immediately on drafting statutory changes to law, code, standards etc to ensure fit-for-purpose rules that work for people, communities and New Zealand.

Declaration: Because the councils and central government have multiple interpretations of the same words, the industry is being shaken by uncertainty, and the government is blocking one of its potentially most effect, immediate, medium-term solutions to the affordable housing crisis. A high court declaration will address this.

Clarification: Once a declaration is made, the crown can promulgate to all territorial authorities and building control authorities the court findings, along with policies, procedures and interpretations to bring clarity to the questions and uncertainties.

Legislation: It is clear the current regime is not working for all parties. Law and rules need to catch up to the status quo, and they need to be fit for purpose, most notably understanding that the units in question are designed for reversible land use (see definitions, above) which is very different than the permanent land use inherent with buildings and structures. It also is acknowledged that the cost and time delays inherent under the RMA and Building Acts don’t work satisfactorily with the target market, but in fact are toxic to it.

Interim Solution: NZ is a pragmatic country, small enough to respond rapidly – as for example, it did in the Christchurch Earthquake when 10,000 homes were damaged or destroyed. The affordable housing crisis is not as shocking or violent, but it is, in fact much larger. Accordingly, it is proposed that a Voluntary Code of Practice be written and agreed to by all parties as an interim measure to ensure people are properly housed for the time it will take before legislation catches up.

Proposed Voluntary Code of Practice (conversation starter)

The key to a successful voluntary code of practice is that it addresses as many of the several party’s concerns as it can, and it does not remove de facto control from the councils. At present, the councils exert control, even if ultra vires, because they can. A voluntary code must enable them to retain control in the event of non-compliance to the voluntary code. That is accomplished by an agreement that is based on the industry & customer compliance and in the event of non-compliance, the certified unit loses its certification and becomes an unprotected target.

ID PLATE: The visible point of reference for each Chattel Shelter Unit (mobile home) in the field is an ID Plate and an active GPS sending unit that is connected to a type-approval document attached to a serial number assigned to the actual unit. At any time, an official should be informed precisely where the unit is, who its owner/occupants are and its typology-compliance certificate. This plate (with QR Code) is fixed to the outside of the unit.

SPECS PLATE: Inside each unit, in an easily locatable location (probably near the switch box), an A4-size permanent plate sets out important consumer information, including a note the unit is chattel not a building and is neither annexed to title, nor part of the land, and remains a mobile home unless fixed to land with a building consent approved.

TYPOLOGY CERTIFICATE & GPS NUMBER: In a central database, the crown maintains typology certificates for each certified chattel shelter type and register of each mobile home registered under the typology certificate. The certificate contains all the compliance requirements to maintain its validity. Any mobile home that breaches its requirements loses its certificate and the territorial authority is automatically notified.


  • A1: The Voluntary Code of Practice (VCP) applies to mobile homes, and some factory-prefab flat-pack shelter. This version of VCP does not apply to converted containers or DIY products because such inclusion may confused and delay agreement.
  • A2: The defined words in the prior column (“Interpretation”) are included herein
  • A3: The mobile homes covered in the VCP pose low-to-normal risk to human life or the environment because they are very small, very simple, and are usually one door or window away from the outdoors on ground level. The maximum size of an approved mobile homes is a LTSA Category Three oversize dimension, which inherently ensures strength to withstand live and dead loads. mobile homes are inexpensive to buy, to maintain and to repair. 
  • B1: The mobile home are designed to sustain more challenging condition than buildings built in situ, because they must endure road travel on NZ roads, including badly maintained ones, without suffering significant damage. They must travel at speeds of up to 80 kph, in both calm and windy conditions. This ensures the mobile home will be more durable in an earthquake. mobile homes may be anchored to the ground using guy lines (cables, chains, etc.) to prevent wind loads from moving them, provided the lines are removable.
  • B2: Unlike buildings that are designed to remain in situ for no less than 50 years, mobile homes are designed so that each component is easily accessed, including all underneath, because the mobile homes are designed to be lifted by hoist, crane or jack. Accordingly, they are designed to be refurbished on a 15-year cycle with a 5-year Warrant of Fitness inspection conducted by a Qualified Independent Person.
  • C: mobile homes must be made of fireproof or fire resistant materials. Further, because of their size and design, they generally have one door or window between occupant and the ground-floor outdoors and they are placed in stand-alone locations that allow conscious people to escape rapidly. Because of their small, single-floor size, access and safety for firefighting operations is at the lowest level of risk, and the low height poses low risk in the event of total fire consumption
  • D: mobile homes have direct access to the outdoors. With the exception of mezzanine stairs and ladders in some tall units (not taller than 4.3m above the ground), there are no stairs or lifts, other than outside stairs or ramps for people with disabilities, to entry doors and decks – under one metre above ground level.
  • E1: Surface water is controlled with impervious roofing that sheds storm water and snow melt.
  • E2: External moisture is controlled either by conventional cavity-batten wall design, or by panels that do not absorb or are not affected by external moisture. Each typology certificate contains details on how it prevents external moisture from causing adverse effects such as undue dampness, damage or degradation to building elements, condensation, or fungal growth
  • E3: Internal moisture. Because mobile homes are small and simple, internal moisture control is simpler than with buildings. Each typology certificate contains details on how it prevents internal moisture from causing adverse effects.
  • F1: Approved mobile homes are not permitted to be made of hazardous agents or substances
  • F2: Approved mobile homes must use safety glass following the standards in NZS 4223.3: 1999 or current
  • F4: Approved mobile homes have few safety from falling hazards because of their size and design. With the exception of mobile homes with mezzanine steps or ladders, mobile homes are ground floor designs with no fall greater than 1 metre.
  • F5: mobile homes are manufactured in factories, not constructed in situ.
  • F6: Most mobile homes have direct access to a door or window leading to the outside and ground level.
  • F7: All approved mobile homes must have approved domestic smoke alarms installed and operational with one alarm in each domestic sleeping space.
  • G1: Some mobile homes are sleepouts or day work-spaces meaning they do not have bathrooms. Others contain toilets, showers and basins. Additionally, some designs use multiple mobile homes where one may be a sleepout and another a wet-unit that houses bathroom or kitchen/bathroom. It is a requirement of any mobile home that potable water and wastewater are connected to external services in a way that installation and removal can be done by any person, and not require the services of a plumber. This is typically done using the same type of systems used by caravans. 
  • G3: Some mobile homes are sleepouts or day work-spaces meaning they do not have food preparation facilities. Other mobile homes contain food preparation facilities where each specific typology design specifies the facilities and the options (different layouts) contained in the typology.
  • G4: Each typology design describes how adequate ventilation is provided to provide for a safe and healthy interior environment. Because mobile homes are small and simple, such design is simpler than with buildings.
  • G5: A mobile home is one of the most efficient uses of habitable space on the market. As ground floor units, they are easy to make accessible for people with disabilities. As small, efficient units, maintaining a warm, dry and comfortable interior temperature is easily achieved and demonstrated in the typology design.
  • G6: mobile homes are stand-alone units, thus they are single occupancies where household units are physically separated from each other with the outdoors between them.
  • G7: Because mobile homes are no larger than LTSA Category 3 oversize natural light from glass windows and doors provides sufficient light for occupied spaces and appropriate visual awareness of the outside for occupants.
  • G8: mobile homes are provided with sufficient artificial light to safeguard people from injury as set out in the typology
  • G9: mobile homes generally use caravan-type gas and electrical services which meet a higher safety standard than buildings.
  • G10: mobile homes with plumbing use the same systems as buildings.
  • G11: mobile homes that use gas-fuelled appliances are approved by a licensed gas fitter
  • G12: mobile homes with kitchens and/or bathrooms generally are connected to potable water supply with a potable hose connection similar to caravan supply. Hot water is supplied in accordance with the typology design
  • G13: Foul water: Waste water is often serviced the same as with caravans. The typology design will specify the disposal methodology.
  •  G15: As a small unit, standard rubbish and recyling bins are used for solid waste holding and disposal.
  • H1: mobile homes are inherently energy efficient because of their size and their level of insulation.


Compliance testing for buildings adds to the cost of the building. Ultimately such costs are added to the cost of price of the unit, which in the case of mobile homes can render the units unaffordable for the customer or render the business unprofitable for the industry. The alternative is vernacular testing that examines real-life effects rather than desk or laboratory exercises.  It is proposed that wherever possible, vernacular tests are used to demonstrate compliance. The other benefit of vernacular testing is that it often results in the manufacturer over-engineering so the margin of error is greater.

  • Insulation vernacular test: Heat the mobile home to 20° C for 24 hours. Turn off the heat and all energy sources, vacate the unit and close all doors and windows. Using Chart A (to be supplied), the heat must take more than (see chart) hours to drop to half the difference between the outside temperature (see chart) and 20°
  • Durability vernacular test: Each mobile home must be towed or driven 50 km on NZ roads excluding motorways. Inspected by a qualified independent person (QIF). If anything bends, breaks or is structurally damaged, it fails.
  • External water and moisture vernacular test: __________________________
  • Stopping: Every mobile home that is towed must stop within 7 metres from a speed of 30 km/h
  • Safe transport: 

 go to News→