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What To Look For When Performing A Wall Tie Inspection

All over the UK thousands of homes have problems with corrosion and , ultimately, the demise of the wall ties. The most often, the root reason for the issue is the original construction of the house and the initial installation of wall ties, particularly, not enough were utilized. We have extensive knowledge and experience with a variety of property-related issues such as cavities wall tie. This article will take a closer look at the process of cavity wall tie replacements, and how we can assist you in determining the state of the wall tie to replacing damaged wall ties with our cost-effective and non-intrusive repair solutions.

What exactly are Cavity Wall Ties?

Construction of cavities in brick was first introduced as a method of building in the Victorians and became popular by the 1880’s. The two leaves , or skins in brickwork (inner and the outer) are stabilized by the wall ties that are placed with regular spacing in both directions. The first wall ties were usually specially-shaped bricks. They were brittle and steel or iron tie were added. Protection against corrosion was at best an oil-based coating, usually not much. Later the use of galvanised ties. The end that is buried into the mortar bed, and once it is water-resistant, the process of corrosion may begin. This process is made more difficult by the mortar ‘black Ash’ which is made up of chemical contaminants.

Cavity Wall tie fails to connect

The corrosion or rusting of the steel or wrought iron can cause the material to expand, and to de-laminate. The expansion, if it is large enough, will result in the cement bed break into two and rise, resulting in horizontal cracks that show up regularly throughout the wall. Most often, it is the wall facing towards the weather that suffers the most. In the worst situations, the wall tie’s ‘fingers will completely disintegrate creating no direct connection between the inside and exterior brickwork’s skins. Wall collapse can occur when an overwhelming majority of tie’s corrosion has completely stopped.

The steel strip tie was replaced by wire ‘butterfly’ tie ties in the 1960’s and the 1970’s. They are corroded to nothing and don’t usually result in any lifting of mortar beds. However, they must be considered as a total failure could still happen.

The most frequently asked question is: how many years do the ties for cavity walls last before they have an opportunity for them to fail? Because of the nature of the ties for cavity walls, they can be extremely difficult to predict accurately the longevity of ties, particularly ones used for the construction of homes before 1945. Between the years 1945 to 1964,, a relatively accurate lifespan is possible to predict:

Strip ties – They are likely to last between 31 to 61.
Wire ties – The illness is likely to last between 15 to 31 years.

It is evident from the wide-ranging lifespan estimates there isn’t a definitive answer as to how long the life span of cavity wall ties is.

Between 1964 and the year 1981, there is a shift in the time span of the ties:

Strip ties from between 23 and 46 years
Wire tie ties – 13 to 26

One thing that is certain is that any mild steel wall tie will eventually be afflicted from some type of corrosion.

How can I tell whether my ties for the cavity wall have been damaged?

The only way to tell whether a home has damaged cavity wall ties if the wall ties have collapsed and the erosion of the wall ties have resulted in damage to both the external and internal walls.

The indicators to look for in order to identify the signs of a cavity wall tie failing are:

Walls that bulge outwards The joints of the wall expand, causing the wall to expand outwards. This can be seen in the windows.
Cracks appear on the outside wall. Visible cracks occur at regular intervals in the mortar joints of external walls.
Cracks in internal walls Cracks can appear inside at the ceiling and wall joints.
Cracks that appear on any render coats which may be there.

Doing a Cavity Wall Tie Inspection

A first inspection of the wall cavity will reveal the existence of horizontal cracks in the mortar bed at intervals usually of about 450mm. To assess the condition of the wall tie, we find a number on every elevation with the metal detector, then make holes in the vicinity and examine the ties within the cavity using an endoscope.

Sometimes, in a wall tie inspection we see massive corrosion and de-lamination. If there is doubt about the state of the wall ties we can expose the outside by removing the mortar surrounding it. The corrosion can be easily assessed. Sometimes, we discover that not enough wall ties were used in construction. It is recommended to have the average 2.5 tie per sq metres. The survey of metal detectors can be used to determine the distribution. Every elevation accessible is examined unless we are told to do so.

Replacement of Cavity Wall Ties

If the ties in the cavity wall require replacement, the procedure has three phases:
1. Placement of the old wall tie so that they can be put using an offset style.
2. Installation of stainless steel mechanical (expanding) tie-ups or resin-bonded tie. A hole of 10mm is cut through the brick face of the block. Once the tie is put in place, an appropriate colour mortar will be used for filling the holes.
3. The old ties are removed through the removal of mortar surrounding them, or by placing grease-filled sleeves to cover the exposed part. The sleeves or slot are then angled to repair the area.

The job is completed on scaffolding or temporary towers based on the conditions and accessibility. Steel wall ties made of stainless steel are employed since they are resistant to corrosion.