Solid walls of masonry are extremely strong, which is why they have been ideal in construction for hundreds of years! Creating openings in the masonry naturally provides weaker areas, but it is a necessity to add in doors and windows. Above the openings there is a triangle of masonry that is unsupported by anything other than the mortar bonding it to the masonry above, which is why it is important that this is properly supported by a strong window frame or a lintel.
In older properties, particularly those with wooden or steel framed windows, the frame can be sufficiently strong to support the masonry. However, by upgrading to double glazing it is vitally important to ensure that a lintel is installed prior to new PVC windows being installed. In addition, structures with masonry above openings that is not properly supported may require a new lintel. One tell-tale sign of lintel failure is diagonal cracking above a window or door.
We fix new lintels or failed lintels by using Target Fixings' Bar Flex. This is installed into the mortar joint above the window in a matter of hours to provide a hidden fix with very little disruption.