Solid fuel heaters
With the onset of winter it is likely that many building consent authorities (BCAs) will receive a number of building consent applications for the installation of solid fuel-burning appliances. When it comes to the granting of building consents for such appliances, which include woodburners, there appear to be two main areas of confusion.
The first area of confusion lies around the introduction of the National Environmental Standards for Air Quality, which introduced a new woodburner design standard. The other issue is the durability (B2 requirements for solid fuel appliances and whether a building consent can be issued in accordance with the provisions of section 113 of the Building Act 2004.
Before approving building consents that involve the installation of domestic solid fuel appliances, BCAs will need to consider whether an appliance complies with the requirements of the Building Code and should also give close consideration to the requirements of the National Environmental Standards.
The national environmental standards for air quality
Resource Management (National Environmental Standards Relating to Certain Air Pollutants, Dioxins, and Other Toxics) Regulations 2004 are mandatory technical environmental regulations. They have the force of regulation under the Resource Management Act 1991. In October 2004, 14 standards were introduced, including a new woodburner design standard. Solid fuel heaters.
The woodburner design standard specifies a maximum particle emission limit of 1.5 g/kg of wood burnt as measured in accordance with AS/NZS 4013: 1999. The Standard further specifies a minimum thermal efficiency of 65 percent as measured in accordance with AS/NZS 4012: 1999. The woodburner Standard applies to all new woodburners installed in urban areas in New Zealand after 1 September 2005. For the purpose of this Standard an urban area is defined as a property with a lot size of 2 ha or less (20,000 m2).
There are currently 46 woodburners [Addendum: as at 3 September 2007, there 89 woodburners] on the market that meet the Standard. A list of certified woodburners is available on the Ministry for the Environment 
website.
The Standard does not apply to existing woodburners (unless they are reinstalled into a property), open fires, multi-fuel burners, pellet fires, wood/coal stoves designed for the primary purpose of cooking, and coal burners. However, some regional plans may impose other requirements for the installation of all burners.
For further information regarding the National Environmental Standards for Air Quality please see the Ministry for the Environment website.
Durability verses specified intended life
The relationship between the durability requirements of the Building Code and the ‘buildings with specified intended lives’ provision in the Building Act has been discussed for some time. The durability of a building element must not be confused with the intended life of the building. A specified intended life (section 113 of the Building Act) applies to the whole building, not parts of a building and should not be applied to solid fuel-burning appliances.
Clause B2 of the Building Code requires a durability of 5 years for building elements for which access, replacement and detection of failure is easy. Building elements that are moderately difficult to access or replace, or where detection of failure would only occur during normal maintenance, must be durable for 15 years.
Most freestanding appliances must have a durability of 5 years, while most inbuilt appliances and flues should have a durability of 15 years. Where it is proposed that a secondhand appliance be installed, durability requirements and the National Environmental Standards for Air Quality should be considered. A second-hand appliance may appear to be in good condition. However, it would be difficult to be certain that the appliance will meet the durability requirement as it may already be several years old.
When approving building consents for second-hand appliances, some building consent authorities address the issue of durability by granting the consents subject to a waiver of Clause B2 of the Building Code. If a waiver is granted, it should be shown on the building consent documentation, and notification of the waiver must be provided to the Department of Building and Housing as required by section 68 of the Building Act 2004. Ongoing maintenance is the responsibility of the owner. The durability levels given in the Building Code are minimum levels and good maintenance is highly likely to give a longer life.
After 5 years (or 15 years), the heater will have satisfied durability requirements, but this does not mean that its safe working life has expired.
Installation
The recognised Standard that determines specific installation requirements for an appliance is AS/NZS 2918 Domestic Solid Fuel Burning Appliances. The Standard outlines the means for determining the correct and safe installation of appliances and their associated floor protectors and flue systems, including minimum clearances from heat-sensitive materials. It also sets requirements where flues may discharge in relation to buildings.
Manufacturers develop installation instructions to ensure appliances achieve the requirements of the Standard. When approving building consent applications for the installation of appliances, building consent authorities must be certain that the proposed installation of an appliance complies with the manufacturer’s installation instructions.
An applicant will need to provide a copy of the manufacturer’s installation instructions, a site plan showing the location of the appliance, a room plan showing where the appliance is to be located, details of seismic restraint provisions and, if a wetback is to be fitted to the appliance, details of how the hot water will be kept at a safe temperature.
Key points
When approving building consents for solid fuel-burning appliances, building consent authorities should consider the requirements of the Building Code, AS/NZS 2918 Domestic Solid Fuel Burning Appliances, the manufacturer’s installation instructions and the National Environmental Standards for Air Quality.