What is a Cavity Wall?

A cavity wall is a type of wall construction consisting of two separate walls with a gap, called a cavity, between them. The construction of cavity walls became common in the 1920’s and replaced solid masonry construction.  Since the 1950’s, cavity walls have become the most widely used form of construction for houses.

The benefits of a cavity wall when compared to a solid wall include:

1. Thermal insulation: The cavity between the inner and outer walls acts as an excellent thermal insulator. It helps to reduce heat transfer through the wall, making the building more energy-efficient.

2. Moisture resistance: The cavity allows for drainage and ventilation, preventing moisture from penetrating the inner wall. This helps to reduce the risk of dampness, condensation, and mould growth, which can be common issues in solid walls.

3. Sound insulation: The gap in a cavity wall can provide improved sound insulation compared to a solid wall.

4. Structural stability: Cavity walls are generally more stable than solid walls, as the two separate walls act independently. This design allows for better load distribution and can provide enhanced resistance to cracks and movement caused by ground settlement or temperature changes.

5. Fire resistance: Cavity walls can offer improved fire resistance compared to solid walls. The air gap acts as a barrier to the spread of fire.

Cavity Wall Ties

The inner and outer walls of a cavity wall, also known as ‘leaves’, are tied together by cavity wall ties to form a single unit. Cavity wall ties are concealed within the structure of a building, but they play a vital role in ensuring stability. Insufficient or poorly installed wall ties can lead to severe structural issues, including damp penetration, cracks or even the collapse of the walls.

Over the years, wall tie shapes and materials have evolved and older styles are now considered obsolete.  Older ties were subject to failure leading to structural defects and because of this, cavity wall tie failure in older buildings is a common defect.  Failure usually manifests as horizontal cracks along the mortar joints of walls at the upper level or the bulging of walls.

Properties that are affected by cavity wall tie failure can be repaired with the installation of remedial wall ties, followed by the removal or isolation of the existing wall ties. This is the quickest and most cost effective solution to wall tie replacement. However, repairs can become expensive, particularly if the subsequent damage is significant.

To prevent failure in the first instance, modern wall ties are manufactured from corrosion and fire-resistant materials such as stainless steel, and they incorporate a drip formation to prevent the passage of water to the inner leaf.

Avery Surveys

If you are purchasing a house and require a survey to check the condition before you commit to buy, then get in touch. Our surveyors are RICS registered, experienced and cover the whole of the north west and North Wales. We will always make time to discuss the findings of the report with you and answer any questions you may have.

You can call our head office on: 0330 088 5040 or visit the website for more information about the services we provide: Avery Surveyors