This salts analysis was negative for nitrates and chlorides, likely rainwater or condensation damp.
Thermal imaging to assist in the location of cold bridging to a wall.
Hygrometer reading showing a very damp wall.
Timber beam failure caused buy poor flashing maintenance.
Wet rot growth. Repair the leak and the growth will die off.
Cavity wall tie issues in a new building. No tie is achieved due to poor workmanship.