Why are there white patches on the gable? Is it due to in adaquete guttering or pitch of the roof?

The white marks on bricks are caused by salt. When bricks get wet, the salt inside the brick dissolves and leaches through to the surface. Bricks turn white when this water evaporates, leaving salt deposits on the brick face. This process is known as efflorescence and is a common problem.

He has nothing to do with any guttering or pitch , it is salts found in the mortar or the materials used in the construction , and sometimes cause an efflorescence stain.

Come across this quit a lot. It’s actually the salt in the mortar but can easily be jet washed off. Hope this helps Tom

Inflorescence salts on the surface, will wash off