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Do You Know Why You Need Noggings?

02/06/2020

Let's face it, no one likes having to install Noggings in a Stud and Track Wall. But why is it that you need them, and what risks are you taking if you don’t install them?

Noggings are horizontal members which run parallel with the top and bottom tracks and are typically installed in the centre of a steel stud wall.

 

  1. NOGGINGS HELP ACHIEVE COMPLIANCE WITH THE NZBC FIRE-RATED WALLS REQUIREMENTS

Clause B1.3.3 of the NZBC states that a structure must take into account physical conditions that can affect the stability of a building element, this includes both fire and wind. During a fire test the pressure of a static uniformly distributed load test is 0.25kpa. This pressure is applied to the wall as a minimum pressure and noggings may be required to assist in resisting these loads. 

As required Rondo includes noggings in fire-rated walls lined one side ensuring they:

  • Have the structural adequacy to meet the NZBC Clause B1
  • Comply with the fire tested system
  • Noggings assist in compliance with NZBC structural requirements
  • The NZBC addresses structural adequacy requirements of lightweight construction in Section B.

Rondo includes noggings, as required, in their lightweight construction designs to ensure they have structural adequacy to meet the NZBC Section B compliance requirements. 

2. NOGGINGS PROVIDE FOR MORE EFFICIENT DESIGNS

The use of Noggings reduces the unrestrained (torsional/ flexural-torsional) length in a Steel Stud Wall. The greater the unrestrained length, the less efficient the wall design becomes.

For example;

  • Wall (a): Has no nogging installed mid height. The wall studs are 64mm x 0.75bmt and are installed at 600 centres, with 0.375 kPa ultimate pressure and one layer of 13mm plasterboard on one side only– the maximum wall height that can be achieved is 2300mm.
  • Wall (b): Has no nogging installed mid height. The wall studs are 64mm x 0.75bmt and are installed at 450 centres, with 0.375 kPa ultimate pressure and one layer of 13mm plasterboard on one side only– the maximum wall height that can be achieved is 2801mm.
  • Wall (c): Has one nogging installed mid height. The wall studs are 64mm x 0.75bmt and are installed at 600 centres, with 0.375 kPa ultimate pressure and one layer of 13mm plasterboard on one side only – the maximum wall height that can be achieved is 3050mm.

The most efficient wall in this scenario is Wall (c) as it achieves a greater wall height than both Wall (a) and (b), and there is also less Studs to install than Wall (b), reducing both material and labour costs. The above analysis has been checked in accordance with AS/NZS4600 Cold-formed steel structures code.

3. NOGGINGS CAN IMPROVE THE QUALITY OF THE FINISH

Stud rotation can be a problem, outside of structural adequacy and NCC Compliance as well.

Without the nogging, there is a greater chance of the wall studs rotating and this can cause plasterboard misalignment and potentially cracking of the plasterboard. Getting called back to a job where the plasterboard walls have cracked is costly and can also damage your reputation for providing quality workmanship.

 4. NOGGINGS CAN IMPROVE CONSTRUCTION TIMES

When you’re lining a wall on one side only, the studs can rotate during installation of the plasterboard. This can lead to quality problems such as uneven board set joints, misalignment of the framing with the board edges, plumb of the wall and the like.

By installing one row of nogging halfway up the wall, particularly when the wall height exceeds about 4m, the studs are kept aligned, setout is maintained because the noggings are precision manufactured and the studs remain square to one another. This can speed up the installation of the plasterboard as you don’t need to constantly correct the position or rotation of the studs as you fix the linings in place.