Box lintels can be used for internal or external openings and with a variation of wall thicknesses. The IG box lintel has perforations along its length acting as a plaster key. As an optional extra IG box lintels can be insulated.
The IG box lintel is designed to carry the full load of wet masonry as soon as it is installed.
Box lintels are manufactured from pre-galvanised mild steel BS EN 10346:2009 DX51D plus Z600 or grade Z275 to BS5977: part 2, 1983 (BS EN 845-2:2003). There is a minimum zinc coating of 600g/m2 galvanising including both sides.
Box lintels can be insulated with expanded polystyrene and conforms to BS 13163:2008.
Box Lintels must have a minimum end bearing of 150mm on each side of the opening, bedded on mortar. Level the lintel along its length and across its width. Masonry built must be laid on a mortar bed and all perpendicular joints to be filled with mortar.
Care should be taken to avoid shock loading on box lintels when used in conjunction with concrete floors or other heavy units.