Household Tips
StainsCleaningLaundryKitchenDampDIYPestsOrganisingMould is a symptom. Find the water first, because the three kinds of damp have three entirely different fixes and the wrong one costs thousands.
Damp is the household problem that costs the most to ignore and is most often treated as the wrong thing. Almost every failed damp job starts by attacking the mould instead of the water feeding it, and almost every expensive one starts with somebody diagnosing rising damp when it is condensation.
What it covers
Every tip in damp
Condensation is worse in cold weather and appears on cold surfaces. Penetrating damp is worse after rain and is usually a localised patch. Rising damp does not change much either way and is genuinely rare.
Produce less moisture, get what you produce out of the house, and keep the surfaces warmer. In that order, because the third one costs money and the first two do not.
Ventilate, wear gloves and a mask, and wipe it off wet with a mould remover or diluted bleach. Never brush it dry, which puts spores into the air you are breathing.
The location is the diagnosis. Behind furniture on an external wall is condensation. A defined patch that worsens after rain is penetrating. A band along the bottom of a wall is worth a proper survey.
Usually yes. A typical dehumidifier draws around 300W against 2,000W for an electric heater, and drying the air makes a room feel warmer at the same temperature.
Report it in writing, photograph it with dates, and keep a note of when it appears and after what weather. That record is what separates the three causes and it is what environmental health will ask for.
Household chemicals can be dangerous in combination. Never mix them, keep the room ventilated, and test anything on a hidden patch first. Full disclaimer.