Fair wear and tear can be defined as the natural deterioration of a building over time without any accidental or malicious damage. Damage to the property caused by a tenant would be for instance drawings on walls by children or items that was stuck to walls with double sided tape, glue or any other form of material to attach items to a wall or burns or stains to carpets. This will always exclude the normal damage to a carpet due to normal use for instance walking on a carpet which would cause a form of damage to the carpet where you can see which part of the carpet is walked on more often.
The exterior of a premises usually suffers normal fair wear and tear at a greater speed than the interior, as the building is exposed to the elements, for instance the paint on the roof and the outside of the building which is not face brick are exposed to sun and rain. The maintenance of paint and regular repainting of the premises, repainting of the roof and repairs to the gutters which was caused by rain and rust is defined as fair wear and tear.
An easy test for fair wear and tear is, would this happen in the premises if you occupied the premises, even if you took reasonable care of the premises, so is this typically just damage to a property that will occur in time.