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Wall Tie Corrosion


005 cavity wall tie failure replacement test check crack in wall belfast dublin northern ireland NICracking, bulging and leaning walls can often be a sign that cavity wall ties have begun to corrode.  In these instances, it is recommended that a comprehensive survey, inspecting the wall ties, is carried out.  Wall ties in buildings built before 1981, in particular, should have a visual inspection, checking the corrosion levels of wall ties, catching them before they become too badly corroded and start causing visual damage to the structure of the building.  

Life Expectancy of Wall Ties

There are different types of wall ties likely to be in a cavity wall, each with a different life expectancy.  Older ties (pre-mid-1980's) tend to be made from mild steel (eg butterfly ties, or fishtail ties), which will eventually corrode; the only question is when. However, it is impossible to know which type of wall tie is in your cavity wall, and the condition of it, without a visual inspection.

At Stronghold Preservation, we have experienced surveyors who are trained to identiify the root cause of the structural problem, provide a written survey and quotation, and the most suitable remedial action.

External Symptoms of Corroding Wall Ties002 cavity wall ties failure crack in walls masonry brick dublin ireland belfast northern ireland NI

  • Corrosion can occur without any obvious external or internal signs or symptoms. An inspection of any building with cavity wall ties is therefore essential, in any building built pre 1981.
  • Horizontal cracks in masonry walls will often be present, usually at regular intervals, approximately every five - seven brick courses.
  • Extensive corrosion of cavity wall ties can cause an outward bulge of the masonry wall, often without any signs of horizontal cracking
  • Window sills may appear to be arching slightly upwards (upward cambering).
  • Window and door lintels may appear to be sagging.
  • Horizontal cracking can sometimes be accompanied by stepped diagonal fracturesof the brickwork, especially at window and door openings or near the eaves level. 
  • Lifting of roof edges, especially at gables due to the lifting effect of the steel expansion on the brickwork.

Internal Symptoms of Corroding Wall Ties

  • Horizontal cracks in the walls sometimes become apparent internally
  • Window reveals can separate, as the outer leaf is leaving the inner leaf behind, particularly at first floor level.
  • The lifting and dragging action of the outer leaf can cause horizontal cracksin walls at the junction of internal walls and ceilings.
  • Another indication of outward movement of external masonry walls is the separation of floors from skirting boards and stairs.
  • In areas of low deadweight,internal leaf cracking of bed joints can happen due to the tension developed in the inner leaf.

Determining Tie Conditions

At Stronghold Preservation our surveyors will carry out a visual inspection of the wall ties by finding the cavity wall tie with a metal detector, and inspecting the tie within the cavity using an endoscope.  Samples will be inspected at various sites throughout the building.  Should this not be comprehensive then a brick may be removed to confirm the condition of the ties. We will provide a detailed written report on the findings of the survey, along with a competitive quotation for any remedial work required.

Depending on the level of corrosion as assessed by our surveyors, we will recommend the most appropriate course of action.  We provide an insurance backed guarantee for all cavity wall tie replacement work.