A wall tie survey is a specialist inspection designed to assess the condition, placement and effectiveness of the wall ties that hold the inner and outer leaves of a cavity wall together. Over time, wall ties can deteriorate due to corrosion, poor installation or material failure. If left untreated, defective wall ties can lead to structural problems including horizontal cracking in brickwork, bulging walls, movement within the property and, in severe cases, instability of the external masonry.

At Northwest Wall Ties Ltd, we provide comprehensive wall tie surveys carried out by experienced specialists using advanced inspection methods and industry-leading equipment. Our inspections utilise specialist tools including borescopes and metal detection equipment to accurately locate existing wall ties and assess their condition without unnecessary disruption to the property.

Every survey is carried out with a detailed and methodical approach, allowing us to identify signs of corrosion, inadequate spacing, missing ties and any associated structural concerns. We inspect both residential and commercial properties and provide straightforward, unbiased advice based on our findings.

Following the inspection, we produce clear, professional mortgage and lender-ready reports containing:

• Detailed findings and assessment results

• Photographic evidence from the inspection

• Identification of wall tie type and condition

Most homeowners have never heard of wall ties or wall tie surveys until one is recommended by a mortgage lender, surveyor or structural engineer.

A wall tie survey may be required when buying or selling a property, where cracking or movement has been identified, or when there are concerns about wall tie corrosion or failure.

Common reasons for a wall tie survey include:

✓ Mortgage lender requirements
✓ Homebuyer survey recommendations
✓ Cracking brickwork
✓ Bulging external walls
✓ Suspected wall tie failure
✓ Peace of mind when buying a property

Not every wall tie survey identifies defective wall ties requiring replacement. In many cases, wall ties may show minor signs of corrosion or deterioration that, in accordance with BRE guidance, only require further monitoring and re-inspection in 5 or 10 years.

The only way to determine whether remedial wall tie replacement is required is through a professional wall tie survey. If no remedial works are needed, the cost of a survey can be a worthwhile investment compared to unknowingly purchasing a property that requires significant repair costs.

Our recommendations are based on recognised BRE guidance, ensuring complete transparency and impartial advice.

Wall ties are an essential component of cavity wall construction, connecting the outer and inner leaves of masonry and helping to maintain the structural stability of a property. While designed to last for many years, wall ties can deteriorate over time, particularly in older buildings where less durable materials were used.

Moisture and Corrosion

The most common cause of wall tie failure is corrosion. Traditional mild steel wall ties are vulnerable to rust when exposed to moisture within the cavity. As steel corrodes, it expands significantly, placing pressure on the surrounding mortar and brickwork. This expansion can lead to horizontal cracking in mortar joints, bulging walls, and, in severe cases, structural instability.

The Impact of Black Ash Mortar

One of the main factors associated with accelerated wall tie corrosion in older properties is the use of black ash mortar. Widely used in many parts of the UK during the early and mid-20th century, black ash mortar was produced using waste materials from coal-fired furnaces and industrial processes.

Unfortunately, black ash mortar often contains impurities such as sulphates, chlorides, and unburnt carbon. These contaminants can create a more aggressive environment around metal wall ties, increasing the rate of corrosion. When moisture enters the masonry, these soluble salts can be activated, further accelerating the deterioration of embedded steel components.

Age and Original Materials

Many properties built before the 1980s contain galvanised or unprotected steel wall ties that were not manufactured to modern durability standards. Over decades of exposure to moisture and environmental conditions, the protective coatings can fail, leaving the steel vulnerable to corrosion.

COSTAL AREAS

Properties located in coastal areas or regions exposed to driving rain may experience higher levels of moisture penetration within cavity walls. Salt-laden air and persistent damp conditions can significantly increase the risk of wall tie corrosion, particularly where older wall ties are present.

Why a Wall Tie Survey is Important

Corroded wall ties are hidden within the cavity and often cannot be assessed through a simple visual inspection. A specialist wall tie survey uses borescope equipment to inspect the condition of existing wall ties, identify any signs of corrosion or failure, and determine whether remedial work is required.

Early detection can help prevent more extensive structural issues and ensure that any necessary repairs are carried out before significant damage occurs.