Galvanised pressed steel lintels may be used as an alternative to concrete as a means of support to both loadbearing and non-load- bearing internal walls.
Mild steel strip is pressed to shape, welded as necessary and galvanised. The steel lintels for support over door openings in load- bearing internal walls are usually in hollow box form, as illustrated in Fig. 95. A range of lengths and sections is made to suit standard openings, wall thicknesses, course height for brickwork and adequate bearing at ends. For use over openings in loadbearing concrete block internal walls it is usually necessary to cut blocks around the bearing ends of these shallow depth lintels.
Over wide openings it may be necessary to fill the bearing ends of these hollow lintels with concrete to improve their crushing resistance.
The exposed faces of these lintels are perforated to provide a key for plaster.
To support thin, non-loadbearing concrete blocks over narrow door openings in partition walls, a small range of corrugated, pressed steel lintels is made to suit block thickness. These shallow depth, galvanised lintels are made to match the depth of horizontal mortar joints to avoid cutting of blocks.
The corrugations provide adequate key for plaster run over the face of partitions and across the soffit of openings, as illustrated in Fig. 96.
Fig. 95 Steel lintels in internal walls.
Fig. 96 Corrugated steel lintel in internal wall.
These shallow depth lintels act compositely with the blocks they support. To prevent sagging they should be. given temporary support at mid-span until the blocks above have been laid and the mortar hardened.