STEEL FRAME CONSTRUCTION

INTRODUCTION

Light steel frame systems are not too dissimilar to a timber frame construction. Rolled steel sections are constructed in a platform frame structure. The sections are delivered to site pre cut and pre punched, or in some cases are delivered in prefabricated panels. Where panels are not used the method of construction is fairly labour intensive, and as a result not widely used.

The steel frame forms the inner leaf of the cavity wall - with the outer leaf brick cladding or a rendered blockwork as the most common material used. The frame is usually fixed to the substructure using large expanding bolts. The steel frame carries the load of the floors and roof, the cladding is not load bearing. Insulation is usually fitted to the external face of the steel frame, with the plasterboard lining fixed to the internal face. Improved thermal performance can be achieved by placing additional insulation within the frame - but consideration must be taken to the thermal bridging issues that can arise with the steel studs. Given the position of insulation to the outer face of the steel frame, the steel stays warm, and therefore a vapour control layer is not normally required.

The ground floor of a steel frame construction can be either a suspended floor system or a cast in situ concrete slab system. First floor construction is often steel lattice joists fitted with plywood or OSB decking.

The roof of a steel frame system can be constructed using timber trussed rafters or lightweight steel trusses. If timber trusses are used a timber wall plate is bolted to the top of the steel panels. Roof coverings are no different from standard roof construction.

Figure 7.1 - Example of steel frame construction