Steam from the kitchen and bathroom does not stay put. It drifts to the coldest room in the house and condenses there. Here is how to stop it.
Damp air moves from warm, wet rooms to cold, still ones and condenses on the coldest surface it finds. Keep the door of the wet room shut while the fan runs, then ventilate that room. Do not leave other rooms completely unheated. A small amount of steady background heat in a spare room does more good than a closed door.
If the damp is in a bedroom that is nowhere near the kitchen or bathroom, the cause is often upstairs from where the steam was made. Cooking, bathing, drying washing and simply breathing put moisture into the air. Where that moisture ends up depends on which doors are open, which rooms are warm and which walls are cold.
This is the step people skip. Adur and Worthing councils say that heating one room well while others stay cold makes condensation worse in the cold rooms, and recommend keeping some background heat on through the day and leaving doors to unheated rooms open so warm air can reach them. Coventry City Council also says not to leave spare rooms without heat, and suggests keeping the temperature steady and above 15 degrees Celsius to help reduce condensation and mould. The Property Care Association agrees that a modest but constant background heat is better than intermittent heating. Avoid portable bottled gas heaters, which add moisture.
If the fans do little, have them checked, because a weak extractor leaves the moisture to drift. If one outside wall is always the cold one, a surveyor or insulation specialist can look at why. Our guide to cold spots and cold bridges explains what they look for. If the wall is damp when the weather has been mild, rule out a leak first with our rising, penetrating or condensation damp guide.
If doors, fans and heating are sorted and moisture still collects in the coldest rooms, controlling humidity across the home can help. A loft-mounted dehumidifier such as Dryzen is one option for owner-occupied homes with a loft: it has insulated ductwork to the central area or stairway, and it helps stop the conditions mould and dust mites need. A dehumidifier does not stop a leak or rising damp, and it is not suitable for rented homes unless the landlord authorises the changes. Existing mould still has to be cleaned off.
Layouts differ by street. In older solid-wall terraces near the Historic Dockyard, the outside walls are cold, so any room left unheated is where damp air tends to land. Newer estate houses towards Walderslade and Lordswood are often warmer but more airtight, so moisture has fewer ways out and the door habits matter more. See our pages for Gillingham and Lordswood.
Yes while it is in use and the extractor is running. GOV.UK guidance suggests closing internal doors when cooking and bathing to keep moisture contained, alongside extractor fans and open windows. Open the window briefly afterwards so the steam can leave.
Not if it has no heating at all. Adur and Worthing councils say a well-heated room beside cold ones makes condensation worse in the cold rooms, and suggest keeping some background heat on and leaving doors to unheated rooms open so warm air can reach them.
It is often the coldest room and furthest from the extractor, so damp air from the rest of the house settles on its cold outside walls. A little steady background heat and a gap behind furniture usually helps more than shutting the door.
Sources: GOV.UK: Understanding and addressing the health risks of damp and mould in the home; Property Care Association: Why ventilation is important; Property Care Association: Condensation solutions; Adur and Worthing Councils: Damp and mould; Coventry City Council: Condensation, damp and mould
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