Lintels support the wall above windows, doors and other openings. Cracking can develop where a lintel is absent, undersized, inadequately supported, corroded or otherwise deteriorated.
Typical warning signs
Possible signs include stepped cracking from the corners of an opening, horizontal cracking along the line of a steel lintel, dropped or distorted brickwork and windows or doors that bind. Similar cracking can arise for other reasons, including thermal movement or alteration of an opening.
Why steel lintels deteriorate
Where moisture reaches an inadequately protected steel lintel, corrosion can develop. Expansion of the steel may lift the masonry and open horizontal joints. Defective cavity trays or sealant can increase exposure to moisture.
What happens next?
Minor stable cracking may sometimes be monitored. Where movement is progressive, masonry is distorted or corrosion is suspected, further opening-up or structural assessment may be appropriate. Repairs can include replacing or strengthening the lintel, reinstating suitable bearings and rebuilding affected masonry.