# How to counteract damp?



## jiwawa (Jun 22, 2007)

We are long-terming in our van. We've a problem with damp on the ceiling at the side wall seams, inside rear cupboards above the beds . There's a black 'dust', fungus I guess. 

We had our usual hab/damp check done in August and nothing untoward. And last Xmas in Barcelona we had the side rail seals renewed as the guy thought we had water ingress. But now I'm thinking maybe it was condensation all along. I'm assuming that the replacement job would still be intact. 

We've been living in the van since, and doing all our cooking, washing up in there. I do keep toplights open when we're stopped, put lower windows on sneck if not actually open, and use the fan extractor when cooking. I do think the rear area doesn't get much air throughput. 

I also wonder if we should be using the heating? We're very mean with heating and haven't had it on so far this autumn. Do you think that might make a difference? 

I've cleaned the area with a fungicidal spray and have little cupboard-sized 'damp-collectors'. 

I also wondered about somehow lining the problem area with polystyrene? 

I'd be very grateful for any input from folk who've had similar problems. 

Off now to see a bit of Reims! Thanks in advance for any help.


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## boringfrog (Sep 22, 2006)

We live fulltime in our van and damp/condensation can be a problem in cooler Months, plenty of air circulation needed when cooking, we try not to have the heating on but if it's necessary don't have it too hot, we wrap up warm with wooly hats etc until January when we head to Spain. Is it all cupboards that are getting damp? What is stored inside?


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## rayrecrok (Nov 21, 2008)

Hi.

It sounds like your van is not ventelated enough, if you are living in it the ammount of moisture that is generated is quite substancial and it has to be moved on or it just circulates round until it hits a cold spot which turns it back to water..

If you close your curtains or blind over your cab area, is there lots of water collecting on the single glazed glass, thats an example right in front of your eyes.. Give the van a good airing as the moisture even hangs around in soft furnishings and fabrics like clothes in wardrobes, curtains and the such, and it only need a bit of lower temperatures to trigger it all off.

If it was ok in summer and there wasn't a problem then it is condensation, if you had the problem in summer when you get plenty of air through the van then you have a leak.

ray.


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## rosalan (Aug 24, 2009)

The 'evil' damp usually smells sour from the Wet Rot taking place out of site. This can be most noticeable in the cupboards nearest to any leak.

To reassure you, another damp test, using a meter should eliminate the worst fears, which from your description seem unlikely.

May I suggest that first of all you remove any black mould that has formed, the spores of which can be harmful to the lungs. A damp cloth and warm water or some mould inhibitor could be used.

Then try tackling the cause. As far as I know, the only answers are ventilation or dry heat. 

An external front silver-screen, if you are not using one is a first step.

When its not too cold, open any roof ventilators, particularly any near the area of damp and when cooking. Give the van a good dose of heat from time to time, enough to remove any residual damp in the furnishings.

You did not note down the age and make of your van to see if there has been a history of problems such as yours.

Good luck

Alan


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## boringfrog (Sep 22, 2006)

We have a quality external silver screen and an internal one and keep the curtains shut in the cab area, not condensation on the windows, we are getting a bit moisture under the bed (slats) but we lift the mattress every morning to dry out.


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## coppo (May 27, 2009)

We fulltimed in our Hymer S820 for 2 years and never got a bit of damp.

You have to have the heating on at night, make sure windows are on the sneck during the night.

Plenty of ventilation during the day, the more people in the MH the more breathing and subsequently more moisture.

I also used to pull the front bed down a couple of times a week as we were on our way out just to get some air up there.

I also opened all cupboard doors a couple of times a week on our way out for air circulation with the windows on the sneck.

External screens were a must.

Do not dry any wet washing inside if possible and cooking veg used to cause a lot of steam, we found the double skillet good for cooking.

We had underbed heatiing which is why we probably didn't have any damp underneath the mattress.

I used to ask the wife to stop breathing :lol: 

Paul.


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## boringfrog (Sep 22, 2006)

coppo said:


> We fulltimed in our Hymer S820 for 2 years and never got a bit of damp.
> 
> You have to have the heating on at night, make sure windows are on the sneck during the night.
> 
> ...


Do you mean "IF" 
You have to have the heating on at night, make sure windows are on the sneck during the night.


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## FULLTIMER123 (Sep 29, 2011)

Been fulltiming for nearly 7 years now, the secret to prevent condensation is heat and ventilation, we have those small tubular heaters all around the van I built the conversion and allowed for this ie under seat lockers with seat backs set off the sidewalls so heat rises through the gap, also one in washroom with a heated towel rail, heater duct down side of vehicle all down one side, boiler under the bed, if you get rid of the cold spots it helps a lot, we don't even have double glazed window's and suffer very little condensation on these, basically we have a permanent low background heat but al lways have roof vents open a little also a couple of window's ajar, washroom also has a ventilator in the sidewall and again roof vent all way's open a little, in winter if you have a basic comfortable heat but get a little to warm instead of turning heat down ventilate a bit more, our van body is very well insulated and we havn't had a problem in the roof lockers which go all around the van but again while we are static we also leave the doors open a little. As you can see if you heat you need to ventilate to get rid of the moist air before it settles on a cold surface, by having a constant background heat you also minimise the cold surfaces all helps to keep you dry and mould free


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## jiwawa (Jun 22, 2007)

Thanks to you all for your help and concern. 

Ours is a 2007 TEC FREETEC 708TI on a Ford chassis. 

Cupboards across the rear don't seem to be affected, except where the rear meets the sides. Worst affected are those which are jam-packed with clothes, no opportunity for air circulation, so I shall weed those out. 

We do have a good external cover but I nearly left it behind this year as we didn't use it once on our recent 11mth trip - therein may lie the problem! Our reason for not using is that we're nearly always on an aire or wilding, and we always felt we wanted to be able to move off, if necessary, without getting out of the van. Will have to rethink that. We also have internals but haven't been using them either, depending instead on our homemade thermal curtains that fit round the cab. There has been quite a lot of moisture on the cab screen recently so maybe that's a reminder to move to the belt and braces approach. 

On a good note, I replaced the battery on my damp meter and there doesn't seem to be a problem except in a seam where I sprayed fungicide so I'll keep an eye on that. I've all the windows open at the moment and hubby is sitting with his hat on, working on the computer! 

Paul, I was wondering, like borinfrog, if you meant I ought to have the heating on at night (during the night?) or if you were saying that IF I had the heating on, then I should have the windows on the sneck? 

I generally use the double skillet, or a pressure cooker, so not a lot of unnecessary moisture there. And when I do take the lid off I make sure the extractor is running. And no wet washing in the van. But we do go out in all weathers, so we bring our sodden wet gear back in the van. Maybe I should start to hang that in the toilet which is fully plastic-lined. 

It's taken me such a long time to type that on my mobile that I apologise if anyone else has contributed meantime!


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## jiwawa (Jun 22, 2007)

Thanks fulltimer123, I guess these tubular heaters are electric? We spend almost all our time off grid, so they would be a non-starter for us I'm afraid. But I take your point about warm and ventilated.


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## blondy (Aug 23, 2007)

An almost guaranteed cure is a electric dehumidifier, plus warmth,
If you are on electric hookup obviously it's free to run.
You wll be amazed at the mount of water produced.
I have experience of this problem in houses as well.


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## Pudsey_Bear (Sep 25, 2008)

Top lockers usually get used for clothes, if they are full to bursting air cannot circulate at all, in our last van the bottom at the back or the top lockers was open to allow air to circulate.

Oddly older static vans had loads of vent near the floor and the ceiling, and they were fine, but some use them in winter suddenly they got mouldy it might have something to do with the duct tape over all the vents.

We only half fill the top cupboards now, and makes sure we take the stuff out when we get home so air can circulate and dry any moisture out.


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## coppo (May 27, 2009)

boringfrog said:


> coppo said:
> 
> 
> > We fulltimed in our Hymer S820 for 2 years and never got a bit of damp.
> ...


Yes.


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## coppo (May 27, 2009)

JWW said:


> Thanks to you all for your help and concern.
> 
> Ours is a 2007 TEC FREETEC 708TI on a Ford chassis.
> 
> ...


Sorry I was rushing when I wrote it.

To clarify. During the evening when its cold then you need to have the heating on low, but when it is on always have a couple of windows on the sneck. Overnight when you are sleeping always have a couple of roof windows on the sneck as you breathe out a lot of moisture when sleeping.

Chuck the internal screens away, they are useless.

Open plenty of windows during the day.

I think a bit of your problem is that you appear to not want to ever put the heating on. I used to put all 3 heating systems on once a week just to get things warm and it also gave the appliances a tick over.

Paul.


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## jiwawa (Jun 22, 2007)

Thanks Paul. I'm trying to think what 'all 3 heating systems' might be! As far as I know, we've only got the one, the gas boiler. 

Would you open cupboards while the heat is on? My feeling is that that would let warm air in to cool ceiling/wall and that might exacerbate the problem?


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## Agilityman (Aug 17, 2009)

As others have said you need hearing, ventilation and air movement. The heat will increase the vapour pressure within the van. This vapour pressure will 99% of the time (I.e. Not on damp foggy days) be higher than outside and drive the moisture out of the van through ventilated window cracks ( on sneak as you call it). The heat need not be excessive but enough to increase the temperature above 15 degrees centigrade (the general average dewpoint at which condensation occurs). Obviously you need all surfaces above 15 degrees centigrade, hence air movement is needed. You probably won't get the inside surface of the windscreen over 15 degrees centigrade on cold nights, hence expect condensation of the windscreen. Look at condensation on the windscreen as a plus - the vapour within the van has been diverted to the windscreen and not the habitation unit. Obviously dry the windscreen as soon as possible in the morning. Hope this helps.


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## coppo (May 27, 2009)

JWW said:


> Thanks Paul. I'm trying to think what 'all 3 heating systems' might be! As far as I know, we've only got the one, the gas boiler.
> 
> Would you open cupboards while the heat is on? My feeling is that that would let warm air in to cool ceiling/wall and that might exacerbate the problem?


You will only have 1 heating system. We had a top of the range Hymer S820, the insulation was brilliant as well as the build quality.

We sold it a couple of weeks ago as we have now moved back into the house and I am now a wage slave again 

Paul.


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## rosalan (Aug 24, 2009)

The TEC is also made by the Hymer group and will no doubt have good insulation. Perhaps it is even winterised.
I cannot express fully enough the difference between the inside silver screen, which is good for reflecting sun on a hot day, to that of a good external screen; this is a no contest comparison. The external screen stops condensation, keeps the van warm in winter and cool in the summer. After handling it half a dozen times, I do not think it takes any longer to put away than the inside screen; unless it is raining of course.
When we are on hook-up, I am inclined to use a fan heater which not only provides heat, it also circulates the air, which is what you want. My Dethleffs heating runs all around the bed, with heat rising over this whole area and as we both herald from Hymer, I am guessing yours will not be much different..
Assuming you are not in the UK and have a large solar panel to top up your electricity, I am wondering why you are trying to avoid using the gas heating. With Gaslow and others, the cost of gas per-day is not at all expensive if you check it out. Cheaper by far than having damp repaired.

Good luck

Alan


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## Pudsey_Bear (Sep 25, 2008)

FULLTIMER123 said:


> Been fulltiming for nearly 7 years now, the secret to prevent condensation is heat and ventilation, we have those small tubular heaters all around the van I built the conversion and allowed for this ie under seat lockers with seat backs set off the sidewalls so heat rises through the gap, also one in washroom with a heated towel rail, heater duct down side of vehicle all down one side, boiler under the bed, if you get rid of the cold spots it helps a lot, we don't even have double glazed window's and suffer very little condensation on these, basically we have a permanent low background heat but al lways have roof vents open a little also a couple of window's ajar, washroom also has a ventilator in the sidewall and again roof vent all way's open a little, in winter if you have a basic comfortable heat but get a little to warm instead of turning heat down ventilate a bit more, our van body is very well insulated and we havn't had a problem in the roof lockers which go all around the van but again while we are static we also leave the doors open a little. As you can see if you heat you need to ventilate to get rid of the moist air before it settles on a cold surface, by having a constant background heat you also minimise the cold surfaces all helps to keep you dry and mould free


Some pictures would be nice, always good to see another self build on the forum.


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## jiwawa (Jun 22, 2007)

Thanks again folks! 

Agilityman, I found your science lesson interesting and informative - wish I'd listened more in school! 

Yes our TEC is also the Hymer stable and we have the heating pipes going round the beds. 

It's not that we're allergic to putting on the heat, just that we don't unless we need to for our own comfort - and we don't mind sitting with a blanket round our knees! 

But we may have to rethink that if Thelma (the van) is finding things too cold for comfort.


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## inkey-2008 (May 24, 2008)

I have lined all our cupboards with insulation and that stopped condensation forming on the cold surfaces. Also open the cupboards on cold nights so the cold does not build up in them.

Andy


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## jiwawa (Jun 22, 2007)

inkey-2008 said:


> I have lined all our cupboards with insulation and that stopped condensation forming on the cold surfaces. Also open the cupboards on cold nights so the cold does not build up in them.
> 
> Andy


Would that be rigid insulation Andy? I did think aout putting something like that up but then wouldn't that impede the air access from below and above the cupboards?

I was thinking the finer insulation like very thick curtain material might be a possibility?


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## Pudsey_Bear (Sep 25, 2008)

Hmm, as ours is not used yet, hopefully the spray foam in the roof and walls will help with condensation.

Also thinking slightly laterally, what about sticking the carpet or bed mat rolls that some self converters use to the backs of the cupboards to help raise the surface temp, or rather to lessen it's cooling.

Wickes and B&Q also sell polystyrene on a roll.


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## jiwawa (Jun 22, 2007)

Kev_n_Liz said:


> Hmm, as ours is not used yet, hopefully the spray foam in the roof and walls will help with condensation.
> 
> Also thinking slightly laterally, what about sticking the carpet or bed mat rolls that some self converters use to the backs of the cupboards to help raise the surface temp, or rather to lessen it's cooling.
> 
> Wickes and B&Q also sell polystyrene on a roll.


Is that foam actually between the inner and outer layers of the van Kev?

I'm just a bit wary of sticking up some insulation in case there's some condensation gets in behind it and I end up worse than I am at the moment. But maybe I'm worrying too much?


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## Pudsey_Bear (Sep 25, 2008)

I don't have an inner layer as such, just ply where it's needed, but you can't use spray foam on a flimsy, it needs to be sprayed when the van is totally empty.


The spray foam applied to mine before I started to build, also provides the vapour barrier as it is closed cell, the stuff you get in a spray can is not and can even attract moisture.


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## inkey-2008 (May 24, 2008)

I used the polystyrene on a roll from B&Q last year and some sheet stuff that come in a package. I used double sided tape and the sheet type was just a tight fit to hold it.

The year before while in France in November I was getting though a roll of paper towel every morning doing the cupboards and the front window.Last year I did not use any. I have checked behind the insulation and all is okay. The moisture forms on the cold surface it is not coming from the wall, so it will not form behind it. 

I have done the same in a static van and it also works in there as well.

A windscreen cover also helps. I use 2 extractor fans while cooking and don't dry clothing in doors.

Andy


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## jiwawa (Jun 22, 2007)

Thanks folks. We're going to a campsite soon and will use the mini-dehumidifier I have, in the back corner cupboard which may be suspect. Then I'll put up some of the thin insulation material with double-sided tape and see how that goes.

I also thought I'd look out for L-shaped vinyl coated wire dividers like I used to have in the old chest freezer. They would help keep the bits in the cupboards off the back wall, allowing ventilation up and through the cupboard.

However I've just had a look online and can find nothing. Can anyone think of a suitable alternative? 

Many thanks for you all taking the trouble to share your expertise and experiences. I really appreciate it.


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