This standard BS 5977-2:1983 Lintels is classified in these ICS categories:
91.080.30 Masonry
91.060.10 Walls. Partitions. Façades
Requirements for concrete, steel and timber prefabricated lintels, including prefabricated elements used in composite lintels. Maximum span 4.5 m (single storey buildings) or 3.6 m (two or three storey buildings). Covers materials, protection against corrosion, design, workmanship, and includes an appendix giving recommendations for site installation.