Lintels are manufactured in a variety of materials, including timber, concrete, steel and brick. Damage to a lintel can be a direct fault with the lintel itself, or the wall or perhaps even the foundations to a wall.
Lintels within two types of traditional arch are more vulnerable to failure, the shallow arch and the flat arch. Steep arches are generally better designed to handle the pressures and loads from the wall.
In the 1960’s and 1970’s concrete boot lintels were popular. These are particularly prone to failure as they had a tendency to rotate forwards because the outer ledge – while supporting the load – did not bear on the outer leaf of masonry. Bulging or cracking of the masonry above these lintels is commonly seen.
A similar problem can be seen with steel lintels that have a thin shelf supporting the external leaf. The external leaf can rotate outwards if it overhangs the shelf by more than one third of its width, or perhaps if the bedding mortar is soft.
Additionally, expansive corrosion of steel lintels regularly causes damage, and these must be removed once a remedial lintel has been installed. Commonly Helibeams may provide a cost effective concealed solution to this defect.
Arches above openings present a number of issues. Many arches constructed prior to World War II featured a timber lintel at the rear of the arch. If deflection in the lintel, or cracked plaster around the bearing ends can be seen, this is commonly caused by defective timber, this can lead to the full weight of the wall being supported by the external brick arch.
Arches with inadequate or no lintel rely solely upon the window or door frame within them to support the wall above. While older window styles often provided a sufficient support for the arch and wall, problems can arise when windows are replaced during property refurbishment – particularly when uPVC windows are chosen as replacements.
Before removal of the original window frames, a new lintel should be inserted to prevent future problems and wall failures.
The Helibeam System provides a simple, effective solution to repairing damaged or weak lintels, or in situations where no lintel exists but windows are being replaced.
For more information see ‘Replacing windows and lintels in old buildings’.