Getting rid of damp

[Archiesgrandad]

I wonder if anyone can give me a bit of help with a damp problem that we have with our van, a 1996 Pilote Galaxy.

 

The problem started after I removed the old roof mounted Aircon unit, and temporarily stuck a piece of plywwod over the resultant hole using a tube of allegedly sticky sealant sealant from the local Brico, whilst I sent off for a Fiamma roof vent. It was only a few days before the new vent arrived, but in the meantime we'd had a really heavy rain storm, and the sealant turned out to be not so sticky and not totally sealant, so we had a small area of damp around one corner.

 

I fitted the new vent with Sikaflex and that all seems OK now, but I can't get the damp patch dry. Before Christmas I covered the whole van with a huge plastic sheet, so I am confident that no more damp is getting in, but despite having a small oil filled radiator in there, and an electric fan blowing air onto the damp patch, I am still getting quite high readings on my cheap and nasty moisture thingy. The damp patch is only about 2" by 6", 5 by 15 centimetres for the pedants, and I can find no other signs that the damp might have migrated to other areas, I just can't get it dry.

 

Does anyone have any ideas about how I might resolve the problem? Your help and advice will be appreciated.

 

AGD

[Guest pelmetman]

Maybe the roof lining is stained?.....Does it feel wet?........Cant say I'm surprised that any meter picks up damp at this time of year in France :-S .......

 

 

[Archiesgrandad]

The roof lining is stained, but to the touch it doesn't feel wet. By having the oil filled radiator on permanently we seem to maintain a temprature of about 5degrees C, so there is nothing in the van that indicates that damp is a problem, it's quite comfortable in there. The plastic cover has been on the van for more than 2 months now, so I'm pretty certain that no rain can get in, and with the fan blowing air at ambient temperature directly onto the damp patch I was pretty confident that this would draw the moisture to the surface of the fabric to be evaporated, but it seems not

 

.In this part of France January and February are usually considered to be our wet months, but this year has been unusually dry, so much so that the local farmers are saying there is a drought. This is probably a ploy to get more grants from the EU.

 

My damp meter thingy is one I picked up at a show years ago, it has 2 probes in the end and if you press them into the affected area and press the button it makes a buzzing noise and little red lights glow, and the volume of the buzzing and the number of lights illuminated appears to increase towards the centre of the patch, and decrease as you move outwards. I have thoroughly tried the rest of the van, and there is no problem. I have even tried to roughly calibrate the thing by trying it out by gradually increasing the amount of moisture on a damp dishcloth, sad I know, and it all leads me to believe that I have this small area of damp which I want to get rid of.

 

AGD

[ian62]

why not try using a hair dryer directly on the damp area,

[Brian Kirby]

Archiesgrandad - 2017-02-22 4:51 PM The roof lining is stained, but to the touch it doesn't feel wet. ........................AGD

Might it be a plastic coated material of some sort? If so, and the damp is now behind it, it may take a good while yet to dry out - possibly not until you begin to get some warmer spring weather. What you are seeing as a stain may just be the damp material behind, which has possibly darkened and it is that darkening which is visible through the plastic facing. That might explain a) that you an still see the patch, b) that it feels dry and c) that the probes on your meter detect the damp - because they are penetrating the plastic facing and reading from the damp material behind?

 

Rather than attack it further, which will in any case make a mess, why not carry on as you are and wait for shorter nights and warmer days, and then open the van as much as possible when it is fine. Maintaining 5C won't really dry it much, but circulating the air will help. If you can get a bit more warmth inside it won't do any harm - except to your electricity bill!

 

I would also get that plastic sheet off it unless you know there is still a leak somewhere. It will be restricting ventilation, and will also be liable to sweat on the underside on cold nights. Also, with the sheet off, park with the damp area in the sun if possible, so it gets warmed from outside as well as inside. With any luck, it may just gradually fade away.

[Will86]

I don't see any improvement being achieved until as Brian says the weather warms. Its like trying to entice a mouse out of its nest, if the conditions 'aint better then it's staying put.

 

The warm air may be just as moist as the damp patch, its just in a different form (locked in or free) and if all its mates are nice and tight together inside its certainly not coming out.

 

Hygroscopic comes to mind where there's a real moisture battle raging here

 

I doubt it would seriously spread unless there's outside pressure.

[Archiesgrandad]

Thank you all for your thoughts. On balance I think you are all probably right, and I need to be patient.

 

The van is parked against the north wall of the house so although it gets quite a lot of early morning and late evening sunshine, the sun is very low, and has little heat in it. On the south facing terrace it was 22degrees in the shade this afternoon, but we really wouldn't like to store the van on the south side as it would be too close to the house and terrace.

 

I will take the cover off, I put it there in panic when I thought the thing was still leaking as I couldn't get the moisture reading down, but after 2 months with the cover on and no change I think the point is proven, and I shall now keep the fan blowing on it, but the heater might as well be swithced off as it seldom switches in these days.

 

Many thanks guys, you're always there when we need you.

 

AGD