Structural Steelwork and metalwork

Introduction 
Structural steelworks and metalwork are specialist elements of the building and as such are normally the subject of a subcontract. It would be extremely rare for the contractor's estimator to be involved in pricing other than, for example, an isolated steel section to be used as a lintel, or the fixing in position of a fabricated metal window or metal balustrade.
SMM7 takes account of the specialist nature of these elements of construction in its requirements for dimensioned drawings from which the specialist can measure the work involved. The relevant SMM7 sections are as follows:

GIO Structural steel framing
G12 Isolated structural metal members
L11 Metal windows/roof-lights/screens/louvres
L21 Metal doors/shutters/hatches
L31 Metal stairs/walkways/balustrades

This chapter deals with a selection of these elements.

Isolated structural metal members (G12) 
Isolated structural metal members are the most common example of steelwork fixed in position by the contractor's own operatives. Proprietary steel lintels over window and door openings will be fixed in position by bricklayers in the course of their work. Other heavier sections may require craneage.

Metal windows/rooflights/screens/louvres (L11) 

Metal windows are supplied to site complete and ready for fixing to a timber subframe. Aluminium windows are supplied fully finished and often pre-glazed. Example 13.3 assumes that a timber subframe is already in position and has been priced under the timber item L10. 

Aluminium windows are delivered to site with tape protecting the finish and with labelling on the glass. The labelling is to inform operatives that the windows are glazed, and helps to prevent, for example, scaffolding tubes being passed through the glazed window. 

Pre-glazed units will require careful handling, storing and placing in position, which is reflected in the rate. 

Metal stairs/walkways/balustrades (L31) 

In a similar manner to the metal window described above, metal stairs and balustrades are generally measured by number and by reference to a drawing or a manufacturer's catalogue. If the items are supplied for fixing by the contractor, the estimator must liaise with the manufacturer to determine the method of fixing anticipated. It should be noted that mortices in concrete are measured under SMM7 Section E20 or E41. 

It is normal for balustrades and the like to be in sections which are capable of being moved and placed in position by hand. However, if a particularly large component, such as a fire escape staircase, requires mechanical lifting, then the estimator should include for this in the item rate.