NCC 2019 Volume Two
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Part 3.12.3 Building sealing

Part 3.12.3 Building sealing

3.12.3 Application

(a)

This Part applies to—

(i)

a Class 1 building; and

(ii)

a Class 10a building with a conditioned space.

(b)

The provisions of (a) do not apply to the following:

(i)

A building in climate zones 1, 2, 3 and 5 where the only means of air-conditioning is by using an evaporative cooler.

(ii)

A permanent building ventilation opening that is necessary for the safe operation of a gas appliance.

Explanatory information:

Explanatory information:
  1. An evaporatively-cooled building in climate zones 4 and 6 must be sealed because of the likelihood of the building being heated during colder periods.
  2. Appropriate ventilation requirements for gas appliances can be obtained from relevant legislation, referenced standards and product installation manuals.

3.12.3.1 Chimneys and flues

The chimney or flue of an open solid-fuel burning appliance must be provided with a damper or flap that can be closed to seal the chimney or flue.

Explanatory information:

Explanatory information:
  1. The requirements of this Part are to be read in conjunction with the fire safety requirements in Part 3.10.7.
  2. A solid-fuel burning appliance is a heater that burns material such as timber, coal and the like. This clause does not apply to gas and liquid fuel burning appliances.

3.12.3.2 Roof lights

(a)

A roof light must be sealed, or capable of being sealed, when serving—

(i)

a conditioned space; or

(ii)

a habitable room in climate zones 4, 5, 6, 7 and 8.

(b)

A roof light required by (a) to be sealed, or capable of being sealed, must be constructed with—

(i)

an imperforate ceiling diffuser or the like installed at the ceiling or internal lining level; or

(ii)

a weatherproof seal; or

(iii)

a shutter system readily operated either manually, mechanically or electronically by the occupant.

Explanatory information:

Explanatory information:

A roof light should be sealed regardless of which room it serves in climate zones 4, 5, 6, 7 and 8. For example, a roof light located in a hallway should be sealed to stop the transfer of cold air into adjoining conditioned space. This principle also applies to external doors and windows, exhaust fans, ceiling, wall and floor junctions, and evaporative coolers.

3.12.3.3 External windows and doors

(a)

An external door, internal door between a Class 1 building and an unconditioned Class 10a building, openable window and other such opening must be sealed when serving—

(i)

a conditioned space; or

(ii)

a habitable room in climate zones 4, 5, 6, 7 and 8.

(b)

A seal to restrict air infiltration—

(i)

for the bottom edge of a door, must be a draft protection device; and

(ii)

for the other edges of a door or the edges of an openable window or other such opening, may be a foam or rubber compressible strip, fibrous seal or the like.

(c)

A window complying with the maximum air infiltration rates specified in AS 2047 need not comply with (b)(ii).

3.12.3.4 Exhaust fans

An exhaust fan must be fitted with a sealing device such as a self-closing damper, filter or the like when serving—

(a)

a conditioned space; or

(b)

a habitable room in climate zones 4, 5, 6, 7 and 8.

Explanatory information:

Explanatory information:

An exhaust fan is considered to be adequately sealed if it is fitted with a filter such as the type commonly used in kitchen range hoods.

3.12.3.5 Construction of ceilings, walls and floors

(a)

Ceilings, walls, floors and any opening such as a window frame, door frame, roof light frame or the like must be constructed to minimise air leakage in accordance with (b) when forming part of the external fabric of—

(i)

a conditioned space; or

(ii)

a habitable room in climate zones 4, 5, 6, 7 and 8.

(b)

Construction required by (a) must be—

(i)

enclosed by internal lining systems that are close fitting at ceiling, wall and floor junctions; or

(ii)

sealed at junctions and penetrations with—

(A)

close-fitting architrave, skirting or cornice; or

(B)

expanding foam, rubber compressive strip, caulking or the like.

Explanatory information:

Explanatory information:
  1. A close fitting internal lining system is considered to include an allowance for minimum lining movement gaps at wall, floor and ceiling junctions.
  2. Caulking includes sealant, mastic or other gap filling material.
  3. In 3.12.3.5(b)(ii), penetrations include windows, doors, roof lights, flues, exhaust fans, heating and cooling ductwork and the like.

3.12.3.6 Evaporative coolers

An evaporative cooler must be fitted with a self-closing damper or the like when serving—

(a)

a heated space; or

(b)

a habitable room in climate zones 4, 5, 6, 7 or 8.

Explanatory information:

Explanatory information:

The self-closing damper should create an effective seal against air infiltration.