The survey of the current wall ties in a property constructed before 1981 should be conducted in three phases, covering all facades to comprehensively evaluate the state of the existing wall ties.
Phase 1: Visual inspection
Phase 2: Cavity inspection
Phase 3: Tie end inspection
Phase 1: Visual inspection
The surveyor should visually inspect all elevations of the property and make notes and take photos. Special attention should be given to horizontal, diagonal, stepped cracks and bulges in walls.
Photo showing horizontal cracks indicating wall tie corrosion
If no cracking or bulging is noted, this does not mean the property is free from wall tie corrosion. Cracks can be repointed or covered with render coatings, and bulging does not always appear on walls that don’t receive high wind loads. The inspection should move on to the next phase.
Phase 2: Cavity inspection
Using a metal detector, the position of an existing wall tie can be identified and marked with chalk. Then, a 12mm hole can be drilled into the cavity to allow an endoscope inspection if the walls have cavity wall insulation (CWI) installed; then, a brick will need to be removed to inspect the condition of the existing tie. If the cavity inspection finds no corrosion, the inspection should move on to the next phase.
Photo using an endoscope showing that the existing wall tie has rusted away and is no longer tying the cavity wall together
Phase 3: Tie end inspection
Using a metal detector, the position of an existing wall tie can be identified and marked with chalk. Then the bed joint is chased out to expose the existing wall tie to inspect the condition of the existing wall tie end embedded in the external wall. If the tie end inspection finds no corrosion, then you can report that the property is free of wall tie corrosion and recommend reinspection in ten years.
The photo shows that the existing wall tie end embedded in the external wall has rusted out.
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