Fretting is caused when weathering and natural decay causes voids to open in the mortar.
Once the water has entered the brickwork, it can cause significant damage through a number of processes including salt dissolution and deposition. If mortar pointing isn’t performed to minimise this damage, the brickwork will become unsound and will cost thousands of dollars to fix.
The repair process is quite simple, but the art lies in the colour matching of the existing mortar. If this is done poorly it will devalue your residence rather than increase its value. Do not trust this to just anyone to carry out the repairs to your property.
Next time you’re outside have a look at your external brickwork and check for signs of fretting mortar. A simple once-over now could save you some money in the long run.