For cavity widths 70-85mm, extra heavy duty load L5 Lintel has a manufactured length in 150mm increments.To achieve loading figures, lintel can be built in with blockwork as shown. Ensure all perpendicular and horizontal joints are filled with mortar, then place the mortar bed on top of the blockwork before floor units are laid to provide even distribution of load. they cna also be propped to facilitate speed of construction.