NCC 2022 requirements for glass in buildings

Using the NCC 2022 Housing Provisions for glazing

The Performance Requirement H1P1 in NCC Volume Two for structural reliability and resistance includes provisions for structural reliability and resistance for glazing. It is satisfied by adopting Part 8 of the NCC Housing Provisions.

Part 8 includes glazing sizes and installation requirements for:

• Glazing used in the perimeter of buildings, fully framed or supported on all sides. Provides glass thickness based on the size of glass for monolithic annealed glass for wind classifications up to N3. Also dependent on length.
• Monolithic annealed glass (formerly known as ordinary annealed glass) is glass that has not been tempered or toughened which is restricted in the use of 3 mm monolithic annealed glass, to a maximum area of 0.85 m2.
• Glazing used in areas where the potential for human impact could occur which includes:
  • Doors
  • Door side panels
  • Full height glass panels
  • Glazed panels, other than doors or side panels, on the perimeter of rooms
  • Kitchen, bathroom, ensuite, spa room and splashback glazing
  • Visibility of glazing
  • Identification of safety glass.

What has changed in NCC 2022?

A notable change in NCC 2022 Housing Provisions is the alignment of requirements for glazing in kitchens and splashbacks windows and doors (including cabinet doors).

Now, the lowest sight line must be less than 2.0 m above the highest abutting finished level of the floor - for bathrooms, spa rooms and ensuites.

This change requires that glazing Grade A safety glazing material must be used for panels or doors with any edge exposed. They must also be toughened safety glass with a minimum nominal thickness of 6 mm.

Monolithic annealed glass can be used in splashbacks, provided the splashback is fully backed by and continuously adhered to a solid wall material and a fixed cabinet or bench is located in front of the splashback that has a height not less than 760mm, a depth not less than 300mm and extends its full width.

Using AS 1288 for glazing

AS 1288 contains information on glazing beyond what NCC provides. This includes glazing for glass barriers/balustrades and sloped overhead glazing.

To determine the required thickness of monolithic annealed glass, toughened, heat strengthened and laminated annealed glass, the Standard provides either a ‘General Design’ criterion, which requires using first principles and caters to ‘Standard Designs’.

‘Standard Designs’ consider the design wind pressure, the span of glass and also the aspect ratio which relates to how the glass is supported and the ratio of that support.

AS 1288 also goes beyond what the Housing Provisions provide in relation to glazing that may be subject to human impact, where it considers residential and non-residential buildings.

Should I adopt the NCC or AS 1288 for glazing?

Adopting either the NCC glazing provisions or AS1288 will satisfy the Performance Requirements in the NCC, so both are a legal pathway for glazing compliance.

As noted, there are restrictions when using the NCC based on wind classifications. The Housing Provisions note that glass used must be of a type within the scope of AS 1288.

Also, the NCC is not as extensive as AS 1288. This can provide more flexibility provided a practitioner possesses the knowledge required in utilising the pathway in AS 1288 to determine glass thickness and glass type.

To find out more, contact HIA's Building Services team.

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