Damp or Bad Ventilation??

[TheTravelMan]

I started caravanning this year, so we bought a 5 berth 1990 Elddis Cyclone GTX as our 1st caravan.

There didn't appear to be any signs of damp, however over the summer we have used the van regularly. We are finding that the underside of the seat cusions at times are becoming very wet / damp, mainly the ones at the rear of the van. a couple of times we have found slight dampness on the rear walls also but more like condensation, this tends to happen mainly at night. Could this be damp or do we need more ventilation ie: more under seat/unit air vents? we always keep the rooflights open when using the caravan, and tend to open windows or doors during daytime. I now have the caravan stored away indoors for the winter. has anyone suffered this problem or advise what the problem maybe. Any comments appreciated. Many Thanks. Andrew.

 

[gypsy]

If the boards under the cushions are solid,drill a few holes in it this allows air to the cushions,we used to have this problem on our first Van, some people use the thin rush mats, (that are sold at all seaside places)and put those under the cushions but I think drilling a few holes is the way to go, we alway leave a window on a night catch, even when sleeping this helps with condensation,I am sure other members will come along and give you a few more Ideas.

 

[cooky1]

We get a bit of condensation under our cushions because of the van being kept warm and the outside temperature falling at night. Every morning when we go out we lift all the cushions and stand them on their sides to air off. I don't think you have a problem with damp in your van - just try to get the air flowing as much as you can. HTH.

Graeme.

 

[RobRoy]

Hi Andrew,

Condensation ought not to be a problem where the mattresses are on slats - or on solid plywood with ventilation holes as suggested.

We had the codensation problem on our first vans but someone told us that a sheet of fairly heavy brown paper under the mattresses would cure it and, from then on, carried brown paper and had no further problems.

Rob S.

 

[ProfJohnL]

Hello Andrew,

It sounds as though you have a condensation problem, rather than a water leak.

Condensation occurs when warm air which can hold more water vapour comes into contact with a colder surface. Good ventilation is usually the answer, so the suggestion of creating holes in the under matress should help.

It may surprise you to know that an adult exhales about a pint of water every day, so at night in a caravan the humidity is likly to increase.

 

[gary]

John of course is correct about condensation forming when warm moist air stikes a cooler surface but why is that surface cooler?

The wall will be insulated so the inner surface 'should' be at the same temperature as the rest of the van, this then prevents condensation forming. If however the wall has an internal damp problem this damp will keep the inner wall cooler as will simply inadequate insulation.

 

[John_5040782]

Our previous van was an Elddis with solid plywood base for the mattresses. We always slept on the mattresses upside down and then reversed them to their normal position for the day. We had no problems then, but venting with holes in the ply or substituting with slats is definitely a good idea.

 

[ProfJohnL]

Hello Gary.

The temperature distribution inside a caravan and its lockers is generally very uneven, and wide differences can be found. From tests I did a few years ago with and outside temperature of 0 degrees C it was common to find a temperature difference of 20 degrees C between floor (5) and ceiling (25) in a caravan with only a convector heater. The introduction of blown hot air systems if correctly installed could reduce this to only 3 degrees.

Bed lockers are not designed with free ventilation in mind so they are not likely to assimilate to the same temperature and the main cabin

The under bed lockers would only warm up if a hot air duct passed through them, but as soon as any insulative items were put into the lockers, the temperature dropped. Some lockers have fixed external ventilations so their temperature could be considerably lower than the main cabin.

Condensation on bedding, or more specifically on the underside of mattresses is caused by a warm body, which also produces some skin moisture, warming the inside of the bedclothes. This sets up a temperature gradient between the inside to the surface of the bedclothes, and moisture will tend to track from warm areas towards cooler ones.

When it reaches the surface, the blankets on top have the opportunity to allow the moisture to evaporate into the air, but the underside of the mattress meets the top of the bed box, and where the bed box is cooler there is less opportunity for the moisture to evaporate and so it can collect as condensation on the bottom of the mattress.

Some people will leave the heater on overnight but turn off the blown air system and so the problem can occur.

 

[TheTravelMan]

Thanks everyone for your help and much appreciated comments. At least it looks like I don't have damp and with a few tweaks I may be able to help stop the problem. Thanks again. Andrew.