For cavity widths 90-105mm, extra heavy-duty load L5 Lintel manufactured length in 150mm increments. To accomplish loading statistics, Lintel must be built in with blockwork. Always make sure all vertical and parallel joints are filled with mortar. In oder to do this, place the mortar bed on top of the blockwork before floor units are laid to deliver even distribution of load. Lintels may be propped to accelerate speed of construction.