Cavity Wall Tie Replacement

Gen Damp are experts in all forms of wall tie survey and installation. From identifying the type of wall tie through to the correct treatment, you can ensure Gen Damp will treat your remedial wall tie problems efficiently and professionally.

Cavity wall construction has been around since the early Nineteenth Century and became part of normal building practice from the late 1800’s until the present day.

The principal advantages of cavity wall construction are:

While the materials and construction methods of cavity walls can often vary, all methods rely on a tying mechanism to connect the inner and outer leaves and give the wall strength and stability. Therefore cavity wall ties are the crucial structural element within cavity walls.

Historically many different types of materials were used for wall ties including in some areas wood and slate. The most common materials used since the late Victorian era have been iron or mild steel and it is the corrosive properties of these type of ties that have caused the greatest problems.

It is often incorrectly quoted that properties built post 1981 are free from the risk of wall tie corrosion and associated problems. This is because after this date wall ties were of a higher specification, usually stainless steel or galvanised wire, while this greatly reduces the risk of failure it does not completely eliminate it.


The older types of tie either have no protective coating or they sometimes have a bituminous or light Zinc coating. Either way these ties are highly susceptible to corrosion in the presence of moisture and Oxygen. The extent and the rate of corrosion depends on several factors and these include


Wall tie corrosion can lead to a situation varying in severity from future maintain ace to a catastrophic collapse of the structure. As tie corrode they expand and this expansive corrosion can produce distinctive horizontal cracking within the mortar bed joints, usually, though though not exclusively to the outer leaf. These problems are normally associated with the thicker metal and Fishtail type of ties.

Wire ties and other thin metallic ties are unlikely to expand sufficiently to cause horizontal cracking unless the mortar bed joints are very tight(thin) or mortars very hard. Patterns of horizontal cracking can seriously destabilise the structure of the property and accelerate the rate of corrosion by increasing the ties exposure to moisture.

Wall tie density:

The pattern of existing wall ties in most older properties is often found to be irregular and the overall density of ties is frequently inadequate. This leads to areas of major concern and weak spots in these types of properties, these areas are usually

Historically there was no additional tie allowance to these areas and as previously mentioned this can lead to weak points within the structure.

Wall tie survey:

The key elements to the wall tie survey are as follows:


 The surveyor carries with him several specialist item required to carry out a thorough investigation and survey.

NB Cavity wall insulation is an additional complication in properties with cavity insulation it is necessary to remove a brick to inspect the wall ties, this will incur a charge of £60.00 plus VAT at the current rate

Wall tie stabilisation:

Once the results of the survey are evaluated this will lead to the next stage which can range from no action the ties are corrosion free and working effectively, through to the complete rebuilding of structural walls. However the most cost effective remedial solution generally lies somewhere between these two extremities.

Detailed recommendations are given within Building Research Establishment (BRE) Digests 329 and 401and British Standards Institute (BSI) DD140.

The most common remedial tratments are as follows:

Remedial wall tie installation:

 A wide selection of remedial ties are available and it is crucial the right tie is recommended for each individual property. The selection should be based on the results of the survey and in particular the inner and outer leaf substrates and cavity width.

Treatment to existing ties:

Where the repair dictates treatment to the existing ties these must fist be located, usually with a metal detector and/or a Boroscope

NB if a property is in need of general repointing it is a good idea both financially and aesthetically to undertake these works at the same time as treatment to existing wall ties.

Remedial wall tie installation is a technical solution to a common structural and durability problem associated with cavity wall structures. It should not be undertaken by non – specialists or as a DIY fix. Like other common remedial treatments such as damp, fungal attack and woodworm eradication. One of the most important factors that the client is paying for is peace of mind and confidence the work was carried out by experts and that the property is safe to live in, and that it will retain its market value.