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What To Consider About Cavity Wall Tie Replacements

The construction of a cavity wall has been in use since the beginning of the Nineteenth Century and became part of the normal building practices from the end of the 1800’s to the current day.

The primary benefits of the construction of cavity walls are:

Insulation for thermal energy
Sound insulation
Blocks water from the outside.
For stability and strength to the structure.
In order to permit the evaporation of the moisture out of the structure

While the building materials and techniques of cavity walls differ, they all require a tying mechanism to join the leaves on the inside and outside and provide the wall with the strength and stability. So, cavities wall ties are the most important structural component within cavities.

In the past, a variety of materials were used in wall ties, including in certain regions slate and wood. The most commonly used materials from the late Victorian time period have been mild steel or iron, as well as the corrosion-prone characteristics of these tie which have caused the most trouble.

There is a common misconception that houses built post 1981 aren’t at risk of the threat of corrosion in wall ties and related issues. This is due to the fact that after this date, wall ties were made to an improved specification, typically galvanised or stainless steel although this significantly decreases the chance of failure, but it doesn’t completely eliminate the possibility.


The older types of ties are either without a protective coating , or contain a bituminous or thin Zinc coating. In any case, they are extremely susceptible to corrosion when exposed to conditions of humidity or oxygen. The degree and speed of corrosion will depend on a number of variables, which include

Exposure to weather patterns
Type of mortar : Black Ash and weak mixes, as well as porous lime mixes
Pointing condition
Construction and design that is not up to scratch, blockage of cavities, and lack of DPC’s or membranes
Environmental issues, such as costal sites.

Wall tie corrosion could result in a scenario that varies in severity, from a future maintenance the ace, to a complete structural collapse. As ties age, they expand, and this corrosion may cause distinct horizontal cracks in joint joints of mortar generally, but not always on the leaf’s exterior. The problems usually occur with the heavier metal and Fishtail kind of ties.

Wire ties as well as other thin metallic ties will not expand enough to cause horizontal cracks, as long as the joints in mortar beds are extremely tight(thin) and mortars that are very hard. Cracks that are horizontal could seriously weaken structures of the building, and can increase speed of corrosion increasing the exposure of the ties moisture.

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Wall tie density:

The structure of the wall ties found in the majority of older homes is usually observed to be uneven and the overall density of the ties is usually not sufficient. This can lead to regions of great concerns and weak spots within these kinds of buildings These areas are typically

Windows’ sides and doors
Eaves and Verge levels

In the past, there was no tie allowance for these areas, and as mentioned , this could lead to weakness in the structure.

Wall tie survey:

The most important elements of Wall tie surveys are:

The location and the approximate age of the property’s location and approximate age
Choose the method of construction. cavity or brick construction. Both leaf materials are used. The shape of the construction may be altered even in the walls of the same building within north-easterly areas. North East it is common for walls that are at ground level to be converted into cavity walls when they reach the one floor. Also, cavity brick walls are able to change to solid walls when eaves are placed at the gable’s end of a peak.
Mortar type and condition , and the general state of the point
The width of the cavity
The wall insulation is present in the Cavity?
Check for cracks and other obvious indications of movement, bowing or bulging walls
Pay attention to the horizontal cracks which have been fixed and replaced
Determine the pattern and amount of existing connections
Determine the condition of the existing ties, as well as the severity and extent of any corrosion
Does the location of corrosion-prone ties match the site of any cracking that has been previously noted?
Differentiate between cracks caused by corroded tie ties and cracks caused by other types of corrosion-prone metals, such as cast iron lintels, steel down pipes , etc.
Wall tie embedment Are the wall ties sufficiently long to fit the width of the cavity and are they in the correct position


The surveyor is armed with many of the necessary equipment to conduct an exhaustive survey and investigation.

Metal detector to locate ties
Drilling with a cordless hammer drill to inspect holes
EndoscopeOr Boroscope to look at ties in situ
Mortar or mastic to make excellent drill holes

NB Cavity wall insulation is an additional issue for homes that have cavity insulation. It is essential to remove the brick in order to check the wall ties. This is charged at PS60.00 plus VAT at the rate of the moment.

Wall tie stabilisation:

When all the outcomes of the survey are assessed, that will determine the next step which could vary from taking no action to ensuring that the ties are free of corrosion and functional, all the way to the entire reconstruction of walls that are structurally sound. The most cost-effective remedy is usually somewhere in between the two extremes.

The specific recommendations are contained in Building Research Establishment (BRE) Digests 329 & 401 and British Standards Institute (BSI) D140.

The most frequently used treatments for remediation are:

A complete wall tie replacement is advised if the ties exhibit evidence of severe corrosion, and where visible corrosion in the course of inspection
For the majority of walls, the suggested fix density for fixing is 2.5 tie/m2 with further ties at 300mm vertically centred at the edges of the openings as well as up to the verges.
In the case where the ties currently in place are made of thin steel or wire butterfly type that could be able to prevent horizontal cracks generally, it is acceptable to keep them in the same place.
When the corrosion of ties has caused cracks to the leaf’s exterior the ties must be removed or separated structurally from the leaf. This is only possible following an installation process of repair tie and is generally the most costly and disruptive element of stabilisation of wall tie.
It could be that the wall tie is in good shape however they are not dense It could be in situations like these that additional ties can be installed to complement and reinforce the existing tie.

Wall tie repair:

A variety of remedial ties is available , and it is vital that to choose the correct tie for every property. The selection of ties should take into account the outcomes of the survey, specifically the outer and inner leaf materials and the cavity width.

A single product of standardization cannot cover all scenarios and even with the help of a thorough survey, installers will be prepared to handle a range of construction changes
In certain instances, ties could be placed on the outside of the house if major renovation or alteration is underway. This is an excellent alternative since there are no obvious signs for replacement after the works are completed.
In the case of holes being drilled through the middle of bricks that are surrounded by leafs, it is essential to get the closest match feasible by dyeing mortars directly on the spot. Our workers have been trained and are extremely proficient in this area of remedial work.
Experience and supervision of the operator is essential to ensure that tie-ups are correctly installed and that the work is are completed in time and effective.

Treatment of existing relations:

When the repair demands that the existing ties be treated the ties must first be located typically using an instrument such as a metal detector, and/or the Boroscope

Removal of all tie is required when there is a significant amount of damage to the inner and the outer leaves. This requires taking out and replacing the individual bricks. This is slow and labor-intensive and will cost you a lot.
When the damage is only limited to the leaf’s outer surface, the best option is to isolate structurally the bonds away from mortar bed joint. Many methods are possible for this, including isolation sleeves made of made of foam or plastic.

NB that if your property requires general repointing, it’s beneficial visually and financially to carry out these tasks in conjunction with treatments for existing wall ties.

The installation of a wall tie is a technological solution to a frequent structure and durability issue that occurs with cavity wall constructions. It shouldn’t be attempted by anyone who is not a specialist for DIY solution. As with other remedial procedures like mold, damp, and woodworm elimination. One of the most crucial elements that the client will pay for is assurance that the job was completed by experts , and that the home is safe for habitation and will not lose its value.