Condensation Advice

Why condensation occurs

Condensation occurs when warm moist air meets a cold surface. The level of condensation will depend on humidity levels, how moist the air is and how cold the surrounding surfaces are.

If the temperature falls below the dew point temperature, it is quite normal for condensation to occur on any material within a camper, caravan or motorhome that is cold, for example the external walls, plastic windows, etc.

When condensation occurs

Condensation occurs usually in winter months because ambient temperatures are colder (resulting in colder surfaces) and windows and roof vents are opened less so the moist air cannot escape.

Where condensation occurs

Condensation will occur where warm moist air is put into the atmosphere in areas such as in bathrooms (during showering) and in the kitchen areas (during cooking).

In the enclosed space of an RV, the moist air from the kitchen or bathroom areas will inevitably transfer to the rest of the vehicle, which in turn condenses on cold surfaces leading to visible water droplets. This issue is compounded by warm moist air being generated from normal breathing.

Condensation will also form in cold areas where air movement and ventilation is restricted (e.g. cupboards, wardrobes, under beds, etc.)

What is important

It is important to provide ventilation and air flow, so warm moist air can escape, or be externally cooled, and to use the heating reasonably by not making the RV too warm such that occupants perspire, as this will only serve to generate more moist air and therefore more condensation.

It is also important to wipe up any condensation from surfaces to reduce an accumulation of moisture inside the RV and avoid mould forming.

How can you prevent condensation?

1. Open windows to ventilate and allow moist air to escape when cooking, showering, drying wet clothes, towels, footwear or other items kept inside the RV. Pets can also contribute  to increased condensation due to their breathing patterns.
2. Observe when windows begin to show signs of misting and increase ventilation by opening a window slightly by 1cm or opening a roof vent, as these will help, but keep the habitation door closed as much as possible to retain heat. After showering, keep the bathroom window or skylights open, and shut the bathroom door long enough to dry off the room.
3. Try to make sure that the RV is partially heated. It can take a long time for a cold RV to warm up, so it’s better to have a small amount of heat for a long period than a lot of heat for a short time.
4. Fixed ventilation is provided in the RV, specifically through high level vents within the skylights and low level vents through the floor, it is important not to block these.
5. If left unoccupied and unheated for long periods of time the temperatures can soak down thermally into the entire product and become very cold. Whenever possible, put the heating on at a low level before use by pre heating in cold weather.
6. Even with reasonable ventilation it is likely if the temperature is less than 5°C and the humidity high that condensation will occur. Ideally the temperature should be kept about 20°C when occupied particularly in colder weather.
7. In some instances, a dehumidifier may assist in removing excess moisture from inside the RV.