These are the requirements that will meet the NZBC.

They are taken from a report produced by the:

National Association of Steel-framed Housing Inc (NASH).

Download the full report here

Minimum

This is the lowest performance thermal break that will satisfy the present Building Code requirements of E3, Internal Moisture. This minimises the risk of condensation, but thermal bridging still significantly reduces the thermal performance of insulation placed between studs and makes meeting H1 targets difficult. Ghosting could also be a significant issue depending climate zone and cladding.

      Min R0.2 strips (width equal to section flanges) placed over all wall framing (studs, plates and nogs)

Thermal break strips fitted outside the underlay are acceptable with a ventilated cavity. Strips should lap a minimum of 30mm with the cavity insulation each side of the framing and fitted so there are no gaps between them. The thermal breaks fixed to the nogs, bottom and top plates would also need to be thinner than those used on the studs. If 25mm timber battens were used on the studs 10mm chamfered EPS strips could be used on the nogs and plates. The reduced depth would allow air movement and the chamfer would stop any water from collecting.

Better

These thermal breaks minimise the risk of condensation and ghosting. They also ensure there is a good overlap between the wall insulation and thermal break to stop bridging at the edges of the flange and minimises the effects of poor installation.

Wall underlay fixed to the outside of the thermal break. This ensures that any possible condensation is kept away from the framing. NOTE: The insulation must be the same width as the frame + the thermal break to fill the entire space.

Best

As well as the advantages of the Better recommendations, these thermal breaks reduce the temperature difference across the face of the wall top point where they are negligible. They also significantly boost the walls thermal performance, in anticipation of further increases in insulation requirements or allow a reduction in cavity insulation.

Wall underlay fixed to the outside of sheet insulation maximises thermal performance and ensures that any condensation would be kept away from the framing.