What are box lintels?

The term ‘box lintel’ is used to describe rectangular profile steel lintels offered for use in a variety of applications. Box lintels come in two main profiles. The ‘classic box’ is a simple rectangular section, while a ‘box with toe’ lintel provides additional support in certain masonry applications.

It is important to be aware of this variation in box lintel design to suit the different applications in which they can be used. Similarly, some box lintels are offered with integral insulation when it is necessary to minimise heat loss through certain construction types.

Box lintels are a versatile form of structural support, easily coursed in with standard masonry units in solid external walls, masonry cavity walls, and internal walls.

A typical external solid wall is 200 to 215mm wide and comprises a double thickness of standard masonry units (whether bricks or concrete blocks). A steel lintel must support the complete wall thickness, so a box lintel with a toe is used. The toe supports the outer skin of the solid wall while the box itself is faced towards the inside of the building.

For masonry cavity wall applications, box lintels can be used as part of a separate lintel arrangement. The box lintel supports the inner leaf masonry, while a single leaf angle lintel is used to support the outer leaf.

Box lintels with toes can also be used at the top of masonry cavity walls, in closed eaves situations where the loads exceed the capacity of closed eaves lintels or the required lintel length goes beyond 2.7m.

Among the different types of internal wall lintel available, classic box lintels are offered for standard, heavy and extra heavy duty loading conditions, and come in a variety of lengths and depths.

The Catnic lintel product selector allows you to choose the right lintel for the right application, offering a range of filters to help refine the results. When filtering for any of the applications discussed in this post, it will display suitable box lintel solutions based on the other search criteria used.

For any other questions about box lintels, different wall applications, or lintel specification more generally, contact Catnic for expert advice and the solutions that are best suited to your project.