Cavity ties are ties that are used to bind the external wall to the internal wall in order to create one solid unit. Cavity ties are very important for you’re the overall structure of your property as they are a key support framework that your walls are dependent on. If you are in the process of renovating your property, or if you are buying a new property, you might struggle with the decision if you need to get the wall ties of your properties replaced.
It is common for wall ties to age over a period of time but it does not mean that every building that is old will need to get the ties replaced. In fact, there are many old buildings that have stood the test of time successfully while many newer ones require replacement of wall ties time and again. Minor damages and rusting of ties is fairly normal and might not need immediate replacement.
However, the question that confuses most clients is how damaged is damaged enough to require replacement of wall ties. Here are some key reasons why wall ties might get damaged and what degree of repair it might require.
Structural Analysis
Many people get deceived by the structural outlook of the building and believe that it might not need a wall tie replacement. This is usually because it was common to use oversized wall ties in old days. These wall ties were strong enough to stand the time and while they did rust from nooks and corners, a major chunk of those ties stood sound enough to not require a replacement.
However, this might not be always the case and that is why an optical view of the structure can be very deceptive. In order to make an informed decision, it is very important that other factors such as density of the ties used are taken into account. If there are less number of wall ties used, it will mean that each tie has more work to do in order to provide the required support to the walls.
In this case, even minor corrosions might require replacement of ties since each of the tie will need to contribute its full efficiency to provide the required support. However, if the wall ties are used in higher density and there is lesser pressure on each wall tie, then replacement of ties may be delayed.
Cracking
Cracking is one of the most common reasons behind tie failure in cavity walls. There are multiple reasons why cracks may appear, however, the strength and weight of masonry above the wall play a key role. This is because each type of wall tie has its own capacity to withstand a certain degree of weight. If the lintels or the ties are not strong enough to be able to carry the weight of the masonry, cracks might appear. Cracks may also appear due to the process of expansion and contraction in response to changes in temperature and humidity. The constant expansion and contraction of lintels and ties may lead to cracks.
Multiple horizontal cracks that occur due to expansion can grow out to the external leaves of the bricks. Although the inner leaves of the bricks are capable of taking more pressure, the outer leaves are not capable to handle this burden and will require immediate repair.
Rusting and Corrosion
In many cases, ties and lintels corrode and rust due to various reasons. This could be weather conditions such as moisture in the atmosphere that causes rusting or internal problems such as water seepage that may cause the ties to rust and corrode. Major corrosion of lintels and ties will require immediate replacement of ties.
There is no certain guarantee as to how long will the wall ties last before they corrode enough to require a replacement. This is because every region has different weather conditions and the degree of corrosion that your wall ties go through in a given time period depends on the weather conditions and the overall routine maintenance of your property. Other than that, it also depends on the type of material that you have used for your wall ties. High-grade materials are more expensive but they are better at fighting rust and corrosion.
Subsidence
It is not necessary that wall ties will always get damaged due to rusting or corrosion. They often get damaged because there are heavy movements on the ground that triggers ground motions resulting in damage of wall ties. These ground motions can be triggered due to many natural and artificial activities in the vicinity of your property such as mining activity, surface runoff, leakages in underground drainage or running sand. Subsidence activity may result in major damage to wall ties and may require immediate attention.
