This is a photograph taken by Mr Inspector, a qualified building inspector during one of his building inspections in Cheltenham.  It shows flashing gaps which will allow and have allowed water penetration into the roof void and damage to the ceiling linings.

Mr Inspector climbs on the roof during the house inspection and looks at anything that will cause problems.  This can be inadequate flashing, lift or deterioration, cracked roof tiles, rusted and lifted roof sheets, moss build up, chimney cracking, hip and ridge mortar decay and sagging of the actual roof.  All these problems could cause leaking into the ceiling lining.  If we find problems like this during the house inspection and there is no visible leaking on the ceilings, we will then get the thermal camera out to see if there is any damp.