By Luke Field
Lintels are horizontal structural elements that support loads above openings in a building. They are frequently used over windows and doors, both of which represent vulnerable points in a building’s structure.
The older types of lintels consist of timber and brick arches, whereas more modern construction uses pre-cast reinforced concrete and steel lintels. Each material can suffer from defects and failure. For example, timber can decay; steel can corrode; steel reinforcement within pre-cast concrete can also corrode, and this can result in cracking and spalling of the lintels.
You may find that certain low-rise buildings do not have lintels in place above openings. Where these were built with timber frame windows, this provides a certain degree of structural support to the masonry above. However, problems arise when these windows are replaced with modern uPVC which are non-loadbearing. As a consequence, the head of the window deflects over time, and the brickwork above the window may drop and crack.
Typical signs of lintel defects include deflection/bowing to the head of windows or brickwork above; vertical cracking above windows; and stepped cracking through internal or external skins of masonry (above and below windows). Other signs to look out for include out of plumb window openings; cracked subsills; bulging walls; or doors and windows that stick when being opened or closed.
There are many different factors which can result in cracking to building fabric. As such, it is important to ensure the correct diagnosis so that suitable remedial works can be carried out.
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