Stronghold Preservation were requested to carry out a survey to inspect a crack in a wall, in this 2 storey red brick house in Belfast. The house is a cavity wall construction.
To assess the condition of the wall ties, a brick was removed by a Stronghold Preservation surveyor. The wall ties visible were found to be mild steel, rusted and significantly corroded.
An inspection at roof level found that there was vertical expansion of the bed joints. The crack in the wall was therefore attributed to the corroding cavity wall ties.
Further Information
Identifying Cavity Wall Tie Problems
Historically, mild steel cavity wall ties where used in
construction; as mild steel is prone to rusting, over time, the
wall ties corrode (rust), and expand. This expansion of the
cavity wall ties in turn causes expansion of the bed joints, which
can cause the walls to crack and bulge. A visible lift at
eaves level, cracks in the walls, and in severe cases the outer
blockwork leaf falling, are all signs and symptoms of failing cavity
wall ties.
Stronghold Preservation removed the existing rusted wall ties,
and replaced the mild steel
ties with stainless steel ties. The mortar beds were
repointed.
