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13.7

NT Part 13.7 Services

NT Part 13.7 Services

NT 13.7.1 Application of Part 13.7New for 2022

This Part applies to—

  1. a Class 1 building; and
  2. a Class 10a building.

NT 13.7.2 Insulation of servicesNew for 2022

Thermal insulation for central heating water piping and heating and cooling ductwork must be—

  1. protected against the effects of weather and sunlight; and
  2. able to withstand the temperatures within the piping or ductwork.

Explanatory information

The central heating water piping provisions apply to systems designed to heat the building via water, such as a hydronic heating system.

NT 13.7.3 Central heating water pipingNew for 2022

(1) Central heating water piping that is not within a conditioned space must be thermally insulated to achieve the minimum Total R-Value of 0.6.

(2) Internal piping including—

  1. flow and return piping that is—
    1. within an unventilated wall space; or
    2. within an internal floor between storeys; or
    3. between ceiling insulation and a ceiling; and
  2. heated water piping encased in a concrete floor slab (except that which is part of a floor heating system), must in all climate zones, have a minimum material R-Value of 0.4.

(3) All piping located outside a building, or within a ventilated wall space, subfloor or roof space must have a minimum material R-Value of 0.6.

Explanatory information

  • The insulation levels in NT Explanatory Table 13.7.3 are typical examples of materials that can be used to insulate central heating water R-Value. Other methods are available for meeting the Total R-Values required.
  • Piping within a timber member, such as that passing through a wall stud, is considered to have sufficient insulation.
    Insert NT table (13.7.3 (explanatory)) 13.7.3 as follows:
    NT Table 13.7.3 (explanatory): R-Value of the insulation used for smaller diameter piping
    Insulation R-Value
    9 mm of closed cell polymer 0.4
    13 mm of closed cell polymer 0.6
    19 mm of closed cell polymer 0.9
    25 mm of closed cell polymer 1.3
    25 mm of glasswool 1.3

NT 13.7.4 Heating and cooling ductworkNew for 2022

(1) Heating and cooling ductwork and fittings must—

  1. achieve the minimum Total R-Value in accordance with NT Table 13.7.4; and
  2. use thermal insulation material in accordance with AS/NZS 4859.1; and
  3. be sealed against air loss—
    1. by closing all openings in the surface, joints and seams of ductwork with adhesives, mastics, sealants or gaskets in accordance with AS 4254 for a Class C seal; or
    2. for flexible ductwork, with a draw band in conjunction with a sealant or adhesive tape.

(2) Duct insulation located under a suspended floor, in an attached Class 10a building and in a roof space must—

  1. be protected by an outer sleeve of protective sheeting to prevent the insulation becoming damp; and
  2. have the outer protective sleeve sealed with adhesive tape not less than 48 mm wide creating an airtight and waterproof seal.

(3) The requirements of (1) do not apply to heating and cooling ductwork and fittings located within the insulated building envelope including a service riser within the conditioned space, internal floors between storeys and the like.

Insert NT table (13.7.4) 13.7.4 as follows:
NT Table 13.7.4: Heating and cooling ductwork and fittings – minimum total R-Value
Element Minimum R-Value for ductwork and fittings
Evaporative cooling system Heating-only system or refrigerated cooling-only system Combined heat and refrigerated cooling system
Ductwork 0.6 1.0 1.5
Fittings 0.4
Table Notes

The minimum material R-Value required for ductwork may be reduced by 0.5 for combined heating and refrigerated cooling systems if the ducts are—

  1. under a suspended floor with an enclosed perimeter; or
  2. in a roof space that has an insulation of greater than or equal to R0.5 directly beneath the roofing.

Explanatory information

  • Insulation for refrigerated cooling ductwork should have a vapour barrier to prevent possible damage by condensation.
  • The insulation levels in NT Explanatory Tables 13.7.4a, 13.7.4b and 13.7.4c are typical examples of materials that can be used to insulate ductwork and fittings and the R-Values they contribute.
  • For fittings, 11mm polyurethane typically provides an R-Value of 0.4.
  • NT Explanatory Tables 13.7.4a, 13.7.4b and provides R-Values for typical ductwork insulation materials:
    Insert NT table (13.7.4a (explanatory)) 13.7.4 as follows:
    NT Table 13.7.4a (explanatory): Flexible ductwork
    Insulating material and thickness R-Value
    45 mm glasswool (11 kg/m3) 1.0
    70 mm polyester (6.4 kg/m3) 1.0
    63 mm glasswool (11 kg/m3) 1.5
    90 mm polyester (8.9 kg/m3) 1.5
    85 mm glasswool (11 kg/m3) 2.0
    Insert NT table (13.7.4b (explanatory)) 13.7.4 as follows:
    NT Table 13.7.4b (explanatory): Sheetwork ductwork – external insulation
    Insulating material and thickness R-Value
    38 mm glasswool (22 kg/m3) 1.0
    50 mm polyester (20 kg/m3) 1.1
    50 mm glasswool (22 kg/m3) 1.5
    75 mm polyester (20 kg/m3) 1.7
    Insert NT table (13.7.4c (explanatory)) 13.7.4 as follows:
    NT Table 13.7.4c (explanatory): Sheetmetal ductwork – internal insulation
    Insulting material and thickness R-Value
    38 mm glasswool (32 kg/m3) 1.0
    50 mm polyester (32 kg/m3) 1.3
    50 mm glasswool (32 kg/m3) 1.5

NT 13.7.5 Water heater in a heated water supply systemNew for 2022

A water heater in a heated water supply system must be designed and installed in accordance with Part B2 of NCC Volume Three – Plumbing Code of Australia.