NCC 2019 Volume One
Part G2 Boilers, pressure vessels, heating appliances, fireplaces, chimneys and flues (DtS)

Part G2 Boilers, pressure vessels, heating appliances, fireplaces, chimneys and flues (DtS)

Deemed-to-Satisfy Provisions

G2.0 Deemed-to-Satisfy Provisions


Where a Deemed-to-Satisfy Solution is proposed, Performance RequirementsGP2.1 and GP2.2 are satisfied by complying with G2.1 to G2.4.


Where a Performance Solution is proposed, the relevant Performance Requirements must be determined in accordance with A2.2(3) and A2.4(3) as applicable.


To clarify that requirements of GP2.1 and GP2.2 will be satisfied if compliance is achieved with G2.1G2.4.

Where a solution is proposed to comply with the Deemed-to-Satisfy Provisions, G2.0 clarifies that compliance with G2.1G2.4 achieves compliance with GP2.1 and GP2.2.

Where a Performance Solution is proposed, the relevant Performance Requirements must be determined in accordance with A2.2(3) and A2.4(3) as applicable. (See commentary on Part A2).

G2.1 *  *  *  *  *

Blank clause

This clause has deliberately been left blank.

In BCA 90 this provision was performance based. In subsequent editions of the BCA, the provision is covered by the Performance Requirements. G2.1 has been left blank rather than renumber subsequent clauses.

G2.2 Installation of appliances

The installation of a stove, heater or similar appliance in a building must comply with:


* * * * *


Domestic solid-fuel burning appliances — Installation: AS/NZS 2918.

ACT Appendix


To specify the Australian Standards which are suitable to achieve compliance with GP2.1 and GP2.2 as regards the installation of domestic solid-fuel burning appliances, pressure equipment and the like.

Solid-fuel burning appliances and pressure equipment

G2.2 lists one Standard as a Deemed-to-Satisfy Provision for the installation of domestic solid-fuel burning appliances (see G2.2(b)), and for boilers and pressure vessels G2.2 refers to Specification G2.2.

The requirements of G2.2 limits the requirements to stove, heater or similar appliance in a building. Therefore the provision does not apply to boilers and pressure vessels outside of these limitations, such as portable gas appliances.

G2.3 Open fireplaces

An open fireplace, or solid-fuel burning appliance in which the fuel-burning compartment is not enclosed must have—


a hearth constructed of stone, concrete, masonry or similar non-combustible material so that—


it extends not less than 300 mm beyond the front of the fireplace opening and not less than 150 mm beyond each side of that opening; and


it extends beyond the limits of the fireplace or appliance not less than 300 mm if the fireplace or appliance is free-standing from any wall of the room; and


its upper surface does not slope away from the grate or appliance; and


combustible material situated below the hearth but not below that part required to extend beyond the fireplace opening or the limits of the fireplace is not less than 150 mm from the upper surface of the hearth; and


walls forming the sides and back of the fireplace up to not less than 300 mm above the underside of the arch or lintel which—


are constructed in 2 separate leaves of solid masonry not less than 180 mm thick, excluding any cavity; and


do not consist of concrete block masonry in the construction of the inner leaf; and


walls of the chimney above the level referred to in (b)


constructed of masonry units with a net volume, excluding cored and similar holes, not less than 75% of their gross volume, measured on the overall rectangular shape of the units, and with an actual thickness of not less than 100 mm; and


lined internally to a thickness of not less than 12 mm with rendering consisting of 1 part cement, 3 parts lime, and 10 parts sand by volume, or other suitable material; and


suitable damp-proof courses or flashings to maintain weatherproofing.


To provide for the safe design and installation of open fireplaces.

The design and installation of open fireplaces

G2.3 relates to open fireplaces where timber or other solid material is burned and there is generally no in-built enclosing structure or apparatus across the front to contain sparks, etc.

The construction of a fireplace must comply with the structural requirements in Section B of the NCC. The G2.3 requirements relate to additional measures for fire safety.

G2.3(a) states that the fireplace must have a hearth made of stone, concrete or other similar non-combustible material. The non-combustible material must be similar in nature to stone and concrete. The concessions for non-combustible material in Section C of the NCC, particularly C1.9 (such as plasterboard and similar lightweight materials), must not be construed as complying with these specific provisions.

With the increased danger due to the open-fire area, G2.3(a) contains requirements to ensure the area in front of the opening is protected. The hearth is intended not only to protect adjoining building elements from sparks, but also to reduce the danger of logs rolling out. See Figure G2.3.

G2.3(b) deals with the construction of a fireplace (additional to the requirements of Section B). These relate to the fire box, and the need to ensure that the walls adjacent to the fire can withstand the heat. Concrete blockwork is not allowed to form the fire box, because it performs poorly under repeated heating and cooling cycles.

G2.3(c) contains the requirements for chimneys.

G2.3(c)(i) aims to make sure the masonry of a chimney is capable of withstanding heat. The construction requirements are less than those for the firebox, because the most intense area of the fire is below the actual level of the chimney.

G2.3(c)(ii) contains a requirement to line the chimney with a rendering mix to make sure it draws properly. A smoother surface:

  • allows a freer air-flow up the chimney, and therefore removes smoke more effectively; and
  • helps to minimise soot build-up, therefore minimising the risk of chimney fires.

G2.3(d) contains a requirement to ensure that damp-proof courses and flashings are installed. Section 3.3 of Volume Two of the BCA contains some options for compliance.

G2.4 Incinerator rooms


If an incinerator is installed in a building, any hopper giving access to a charging chute must be—


gas-tight when closed; and


designed to return to the closed position after use; and


not attached to a chute that connects directly to a flue unless the hopper is located in the open air; and


not located in a required exit.


A room containing an incinerator must be separated from other parts of the building by construction with an FRL of not less than 60/60/60.


To provide requirements for the safe installation of an incinerator room in a building.

Incinerators, hoppers and incinerator rooms

G2.4(a) contains requirements for incinerators and their hoppers. “Hopper” refers to the area used to feed the incinerator. The requirements for hoppers aim to make sure they do not increase the risk of fire to the adjoining building area.

G2.4(a)(v) states that a hopper must not be located in a required exit. This is to prevent any potential problem where a failure in the hopper could affect the egress route.

G2.4(b) requires an incinerator to be fire separated from the remainder of the building.

Figure G2.3 Fire place clearance from combustible materials