Cavity wall insulation is intended to improve energy efficiency, but when it becomes damp or defective, it can cause serious hidden problems inside a property. One of the most common and most damaging consequences we see at CavClear is wall tie corrosion caused by moisture-laden insulation.
This is an issue that often develops silently over many years, only becoming visible once cracking or structural movement has already begun.
How Damp Cavity Wall Insulation Causes Problems
When cavity wall insulation becomes saturated, it no longer performs as insulation. Instead, it acts as a moisture trap within the cavity. This moisture is held directly against the internal structure of the wall, including brickwork and metal wall ties.
Wall ties are steel components designed to hold the inner and outer leaves of a cavity wall together. In older properties, these ties are often made from mild steel. When exposed to prolonged moisture, they begin to corrode.
As corrosion develops, rust expands to several times the volume of the original steel. This expansion forces pressure onto the surrounding mortar joints, leading to cracking, movement and weakening of the wall structure.
The Link Between Damp Insulation and Wall Tie Failure
Damp cavity wall insulation significantly accelerates wall tie failure. Instead of the cavity acting as a buffer against moisture, the insulation allows water to bridge across the wall, keeping the ties permanently damp.
Over time, this can lead to:
- Step cracking in external brickwork
- Cracking through internal plaster and walls
- Bulging or bowing of the outer leaf
- Reduced resistance to wind loading
- Risk of partial wall collapse if left untreated
By the time these symptoms appear, corrosion is usually advanced and remedial work becomes essential.
Why Removing Damp Insulation Is Critical
Leaving damp insulation in place allows moisture and corrosion to continue unchecked. Even replacing wall ties without addressing the insulation issue risks repeating the same problem in the future.
Removing the defective insulation allows the cavity to dry out properly and prevents further moisture from being held against the wall ties. It also restores the cavity’s original function as a protective barrier rather than a moisture reservoir.
At CavClear, insulation removal is carried out using specialist extraction equipment and controlled access points. All drill holes are professionally made and reinstated on completion, leaving no visible trace.
CavClear’s Approach to Repair
Where damp insulation and wall tie corrosion are present, our process typically involves a combination of:
- Detailed cavity wall insulation and wall tie surveys
- Safe extraction of failed or damp insulation
- Installation of stainless steel remedial wall ties
- Isolation of corroded original ties to prevent further expansion
- Clear reporting for homeowners, surveyors and insurers
- This joined-up approach ensures the underlying cause is resolved, not just the visible damage.
Why Early Surveys Matter
Damp insulation and wall tie corrosion rarely happen overnight. They develop gradually and often remain hidden for years. A professional survey can identify these issues before cracking or movement becomes severe, saving significant repair costs later on.
If your property feels cold, damp, or you’ve noticed cracking in brickwork or plaster, it’s important to investigate what’s happening inside the cavity, not just on the surface.
Book a Professional Survey with CavClear
CavClear are specialists in cavity wall insulation removal, wall tie surveys and remedial structural repairs. We provide honest advice, clear reporting and long-term solutions designed to protect your property.
Call 0333 220 2463 or isit cavclear.co.uk to arrange your survey today.
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