Mould Diagnostic Funnel

C1_Ventilation

External corner / ceiling junction / perimeter edge

Window reveal / head / sill / lintel line

Behind large furniture on an external wall (wardrobe/sofa)

Localised around plumbing / bathroom / kitchen / radiator

Diffuse / random patches (no consistent pattern)

After bathing / cooking / high internal moisture events

After heavy rain / wind-drive rain (storm events)

Spotty mould only (no staining; returns after cleaning)

Staining / tide marks / plaster breakdown / bubbling paint

Furniture <100mm from wall OR boxed-in zone (wardrobe/sofa/units)

Limited air circulation (alcove, curtain, corners) but not furniture-related

New windows/doors (increaed air tightness)

Redecoration: vinyl wallpaper OR acrylic/"wipeable" paint

Heating pattern changed (lower setpoints / redcued use)

Yes (bath/shower/sink/soil stack/radiator/pipe boxing/appliance)