For those who wonder just what a boroscope inspection, for wall tie corrosion involves, here’s a short video I shot in North Yorkshire a few days ago. It is clipped to view the relevant bits – three wall ties are normally looked at when I survey a semi-detached house like this one.
You may have noticed how little corrosion there was on the sample wall tie seen here. This is a very good example of why boroscopes should be used with care. The house has twin gables and when viewed close-up, from a window, there was very wide horizontal cracks in the apex areas – invisible from the ground.
The wall tie survey only came about because the Northwest facing gable was suffering rainwater staining to the soffit of a bedroom window; because water was driving through the expansion cracks and running down the cavity and through the soffit – no cavity tray in this 60 year old house.
The cracks are easily 5mm deep and extend right into the cavity. In the event of strong winds in the vale of York, the apex areas are at a real risk of failure. Had it not been for the water staining, the homeowner would be blissfully unaware that the gable above her kitchen is dangerously unstable.