What is a Wall Tie Survey?

You may be wondering what a wall tie survey is, why you may need one, or you may just be questioning what a wall tie is at all… in which case, before we dive into Wall Tie Survey’s, let us first explain the basics…

What are Cavity Wall Ties?

Wall ties are essentially the unseen metal components in between a cavity wall. They are built into the wall during the construction process and are an essential factor in the stability and safety of a cavity wall.

A wall tie is used to tie the inner and external leaf, referring to the 2 parts of a cavity wall, they span the cavity and tie the internal and external walls of bricks or blockwork together, while locking tightly to the mortar. A crucial part to the stability and integrity of a wall, cavity wall ties provide a ‘lifeline’ to what would otherwise be an unstable independent structure, and instead tie the two leaves together, creating a homogeneous unit. They are also designed to prevent water transfer from the outer to the inner leaves.

Now we have a basic understanding of cavity wall ties in themselves, let’s move on…

What is a Cavity Wall Ties survey?

A wall tie survey can be defined as a specialist survey, in which trained surveyors assess whether the wall ties that are present within a structure are adequately tieing the two leaves together and fulfilling their purpose.

Why would you need a Cavity Wall Tie Survey?

In older houses, the metal ties over time can sometimes rust and no longer be able to do their job effectively, putting risk to the structure itself; this is referred to as a wall tie corrosion. If wall tie corrosion is suspected, a wall tie survey may be taken as a precaution, to check whether it is an issue.

In older cavity constructed buildings with wall ties, corrosion of steel ties is inevitable, with the durability of ties depending on the type of the tie, its coating, and the chemical processes that might encourage corrosion, particularly in houses containing cavity wall insulation, as this traps water and moisture. For example, corrosion is more likely to occur in walls which are more exposed to the weather. The existing ties must be dealt with as the continuing corrosion can result in structural damage to buildings. Such corrosion can result in expansion of the metal embedded in the outer leaf of the wall. While sudden failure is unlikely to occur, it would be prudent to rectify the matter once noted as the defect is liable to affect the value and re-sale prospects of the house. If systems are recognised before damage has progressed too far the walls may be treated rather than rebuilt. A lack of ties in a cavity wall considerably reduces the strength and stability of the wall, resistance to wind loads is impaired and the failure from this cause is possible.

Wall tie corrosion is often suspected when there is evidence of movement in the structure. This can present itself through cracking in the wall, a bulge, or various other defects that could suggest the wall ties are not doing their job properly. This may be noticed by the homeowner themselves, or it is often a matter raised by a surveyor. Find out more here.

What does a Wall Tie Survey involve?

The procedure of a wall tie survey generally takes between 1 and 3 hours to carry out once your wall tie surveyor arrives the exact time it takes can depend on a number of factors for example; if the cavity has cavity wall insulation and or if the property is rendered.

Upon arrival, your wall tie surveyor will carry out an external appraisal of the house, informing them on if there is a cavity wall, if there is cavity wall insulation present, constriction details, and if there are any defects present on the property such as signs of brickwork movement and step/staggered cracking. This will determine the next step, which involves using a metal detector to locate where the exsisting cavity wall ties are in the building and structure. Once located, the surveyor will drill an inspection hole or remove bricks if nessecary near to each wall tie they intend to inspect, this allows the surveyor to use a borescope. The borescope has a viewing window, so your surveyor can look at the ties in the cavity wall and determine whether they are failing or okay. Initially, your surveyor will inspect the visual condition of the wall ties to determine if they are failing, considering the level of corrosion from shiny to rusty or even detached. Other factors, such as defects on the structure, the type of wall tie used, if there are enough wall ties installed and cavity wall insulation will also contribute to your surveyors judgement on your cavity wall ties.

Issues with visibility, often because of cavity wall insulation, may result in a more invasive method to be used for the cavity wall tie survey, to allow the surveyor to see the wall tie fully, rather than through the borescope. Here at CavClear, cavity wall insulation doesn’t stop us from getting you an answer!

At CavClear, once your surveyor has carried out their survey, you will be issued with a detailed and full report, along with our recommendation on whether cavity wall tie replacement is needed, allowing you to move on to the next steps depending on the outcome.

If in need of replacing your wall ties, upon location of the old ties by an electronic detector, the next steps involve replacement of a suitable corrosion resistant remedial fixing and finally isolation of the original ties to prevent further damage to the outer leaf.

What next?

Did we mention… Here at CavClear, we don’t only offer Cavity Wall Tie Surveys, but we also carry out Cavity Wall Tie replacements. This means, we can create a seamless and easy process from determining the fault of your cavity wall ties, to replacing them and preventing further damage to your property. Click Here to find our contact details… or call us on 0333 220 2463.