Daughter had raindrops coming in corner of kitchen. West-facing wall in Scotland so very wet. Traced to the cooker hood vent. Rectangular section with good cowl on outside. Remove flexible trunking for hood to this final section and noted that the *inside* of the duct was completely dry but the *upper* surface was wet. Checked and re-sealed external cowl to wall.
Could this be coming from inside the cavity - since the duct bridges the cavity (which has been insulated in the last year with woolly stuff). Perhaps dripping from wall ties above? If so - how to cure - duct is only a couple of mm from ceiling.
The outer wall is saturated (like the rest of Scotland just now).