Creating openings in walls mean that lintels are a potential weak spot. Defects caused by failing lintels can be complicated and difficult to rectify. We have outlined technical pointers to ensure your build doesn’t suffer from these problems.
- Construct a full masonry unit immediately below lintel ends. Do not use off-cuts of bricks or blocks.
- Ensure the lintel is level and is bedded in mortar.
- The length of lintel bearings should not be less than 100mm and 150mm for pressed steel lintels.
- Certain lintels may need to be propped until the mortar has set under the bearings.
Where prestressed and reinforced concrete lintels are used:
- Build in lintels with the correct side uppermost in relation to the position of reinforcement.
- Prop prestressed composite lintels at centres not exceeding 1.2 m during the construction of masonry above.
- Masonry should be carefully built with solidly filled joints when using composite lintels of prestressed concrete. No holes for services or weep holes should be made nor should anything (e.g. cavity tray) be built into the masonry within the composite zone.
- Exposed faces of lintels must be provided with fire protection.
- Pad stones must be built into the wall to receive the ends of the structural member.
- The size and material to be used for the padstone must not be less than the structural engineer’s specification.
- Pad stones must not bridge the cavity of an external wall.
Chapter 7 of our technical manual provides more information on lintels.
By Anna Symington