Superstructure (excluding roofs)

6.10Light steel framing

applies to ‘warm frame’ and ‘hybrid’ construction
applies to primary structural and secondary components (including external infill LSF walls)
considers LSF flat and trussed roof constructions
provides guidance for key aspects of volumetric construction
does not apply to LSF walls used in basements, and
does not apply to internal LSF partitions, which are dealt with in Chapter 6.3 ‘Internal walls’.

Differential movement	Movement between the frame and cladding, e.g. due to thermal expansion, shrinkage (in concrete masonry) and moisture expansion (in clay masonry).
External infill	Walls which are built between the floors of steel or concrete frames and are designed to resist wind loading and to support the weight of the other wall components. They do not provide stability to the building or resist floor loading. External infill is considered as a secondary structural component.
Hybrid construction	Cavity construction where insulation is installed both between the studs and on the cavity side of the steel frame.
LSF	Light steel frame. In this chapter, ‘LSF’ refers to construction framing members made from coldformed profiles 0.7-4.0mm thick.
Primary structural components	Elements of the structure designed to carry and transfer primary loads of the building as a whole, including self-weight, dead loads and live loads.
Secondary structural components	Elements of the structure which do not play a wider role in the structure, but carry loads directly imposed on them (and transfer them to the primary structure) such as self-weight, wind loads, cladding and openings.
Sheathing	Board applied to the outside of the steel frame (installed where required by the design).
Warm frame	Cavity construction where insulation is installed on the cavity side of the steel frame.