Guide
How to choose a lintel
Choose a lintel by the clear opening plus at least 150 mm of end bearing each side, the wall type it sits in, and the load above it; for anything carrying a floor, roof or point load, the lintel should come from an engineer's design and be approved through building control (a building warrant in Scotland).
Written by the SK Trade team. Last reviewed 1 November 2026.
Measure the opening
Measure the clear width of the opening. Add the end bearing, typically at least 150 mm at each end, to get the minimum lintel length. Steel lintels are made in 150 mm length steps.
Match the wall
Cavity walls use cavity lintels that support both leaves, sized to the cavity width. Solid walls and timber frame use single-leaf or box lintels. Internal block walls often use concrete lintels.
Check the load
Manufacturers publish load tables for standard conditions. Openings with floors, roofs, beams or point loads above need an engineer's check. Making or widening an opening in a loadbearing wall usually needs building control approval in England, Wales and Northern Ireland, or a building warrant in Scotland.
Keep water out
Over openings in cavity walls, a cavity tray with stop ends and weep vents directs water to the outside. Some lintels include a tray detail; others need a separate tray.
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Related questions
Do I need building control approval for a new lintel?
Making or widening an opening in a loadbearing wall is structural work, so in most cases yes. Building control or an engineer will confirm the lintel.
What is the difference between DPC and DPM?
DPC is a strip built into walls to stop damp rising through the masonry. DPM is a sheet laid under a concrete floor slab. They are lapped together so there is no gap.
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