Damp or not? Hymer B544 2000 (1 Viewer)

[3874helen]

Hello all,

well we've had the campervan a couple of months now and have just come back (if a little early to try and address this issue) from a fab trip down France and into Northern Spain and the Pyrenees. What a brilliant time, we were so proud (due to our newbie status) that we managed to stop for free the entire two weeks, keep telling everyone it cost an absolute fortune....we paid four euros in total to fill up and empty on one occasion haha. The previous help people gave me on here when our non-return valve from the tank to the boiler had broken/stuck was great and we fitted a new valve and it solved the problem. We since had an issue with the solenoid valve on the toilet flusher where it was continuously flushing and after a bit of searching on here we rectified that problem too.

So down to the dreaded damp, not sure we can sort this ourselves but I thought it was worth asking the kind people on here again for their help/advice....

We bought the motorhome a couple of months ago, from a number of indicators I think it had not been used for quite some time and the people we bought it from said they'd had it stored in a barn for some time too. So I'm hoping the damp may be a relatively new issue as we're storing her outside. I have a damp detector, quite an expensive one and learnt how to use it before we bought her obviously not totally reliable but the only thing I've got to go on at the moment. Sine we've had her I've found a little damp in the cupboard where the solar panel cable came in through the roof and since we've sealed around the cable that's all dried out to 0%, yay! But also above the fridge I noticed that the wooden plynth behind the stove started to look damp and the wall covering pattern started to "bleed" a bit. I got my damp detector out and it was reading quite high, I could have cried...maybe I did a little..I forget. I've attached photos of the kitchen etc. But basically we decided it was a good idea to reseal everywhere on the whole camper, get an oil heater in there, the damp bag absorption things and recheck in a month or so. So whilst away in our camper it's been lovely and warm, probably 25c everyday so I thought that would have resolved the problem....I checked all of the areas again today and this is what I found:

- Wall behind and above the fridge/hob was between 7% and 12%, it is now reading 0% on the right side but max 7% down the left.
- The wooden plynth (which is now soft and moves up and down now if you push it) at the back of the hob (below the wall) was about 15% and is now 9% max.
- The cupboard floor next to the fridge was about 17% max and is now 0% all over.
- The cupboard next to that (next door but one to the fridge) was about 12% (not near the water pipes (it was zero there) more at the front of the cupboard) and now is 0% all over.

So what I suppose I'm concerned about is at the back of the fridge, the floor there and also above it. What do people suggest? Do we need to go to an expert? Are these levels something to worry about? Could it still be drying out? We've obviously had water in somewhere due to the plynth and the wall being damaged. Should we take out the fridge to see if it's damaged behind there? I would guess that the water will go downhill behind the fridge and could explain the previous high damp readings in the base of the cupboards? Is it a nightmare to take the fridge out (my husband is generally pretty handy)? Any help or advice would be great

Another thing which I wasn't sure if it was related...was the gas kept blowing out on breezy days on our fridge whilst we were away, quite a few times we could hear it relighting, wondered if this was normal and also whether there could be wind blowing rain in through the vent and causing our problem as the vent seems to be exactly where our issue seems to be and it's really well sealed around the edges of the vent there.

Really sorry for the long rambling message, I think I'm a bit over thorough but just wanted to try and make sure I'd included everything.

Many thanks in advance Helen

 

[tonyidle]

I'm no expert on damp meter readings but assume the percentages are 0% for bone dry and 100% if dipped in water. On that basis your readings look to be to be absolutely normal. Bare wood totally exposed to outside air will eventually be as humid (damp) or dry as the air itself. The woodwork behind, above, below, and to either side, of the fridge is totally exposed to atmosphere via the fridge vents. This becomes obvious if the fridge is ever removed as the badly-protected steel parts on the rear go rusty over time.

 

[Lenny HB]

Up to 15% it normally OK but those marks on the wall are worrying. You say you have an expensive damp meter if it is the non- intrusive/paddle type they can measure down to 10 - 20mm depth, the prong type only measure the surface so drying out with a heater the surface type would make it look OK even though there is damp below the surface. For a true accurate reading you do need to spend a few hundred quid on a damp meter, although the cheap £70 non-invasive ones get good reports.
I would say the rear corner joint is leaking, with the type of construction Hymer use it is unlikely to have done any serious damage to the van if it's made the floor soggy may need a bit of work.
I suggest you remove the corner joint strip and make sure everything is thoroughly dry before re-bedding it and a van of that age probably worth re-bedding all the joint strips.
Not bad for a 17 year old van, a lot Brit ones are like that after a year or two.

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[mike mcglynn]

Hi, Helen the fridge vents seem to have been sealed around the edges and as far as I know they are a dry fitting is it possible to remove and take a look, as to me this looks highly likely to be a point of entry for rain dripping from the window surround.

 

[chaser]

Also if it is near the cooker you will have steam from your cooking .

 

[deleted-member02]

View attachment 158804

I also think that the sealed vent hints at potential problems.
It's hard to tell from the picture, it appears to me that there might be additional sealant on the top right hand corner, which also suggests a previous repair?
Perhaps worth taking to a repair shop for an inspection at least...

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[Wagoneer]

You don't show it in your pics but there is an extractor fan that comes out the side of the van in that corner area.

Maybe water is leaking in from the extractor fan vent? Check in the cupboard above the hob for any sign of dampness.

 

[3874helen]

Thanks for all of your replies. We're going to go out and check some things from what's been mentioned and will come back with our findings. Nobodies mentioned taking the fridge out yet, phew, haha.

@Lenny HB - what do you mean by the corner joint strip, sorry if I sound really daft buy do you mean the internal one? And if so once i've removed it do I just leave it off with the heater on for a few days and then reseal it with silicone etc? Also when I said it was an expensive damp meter...it turns out I meant cheap then haha, its just the two prongs.

@mike mcglynn and @kaasbroodje
- it was us who sealed around the fridge vent...we just thought we'd seal around everywhere to protect her, should we not have done this? We'll take the vent off and have a nosey behind there today to see if we can see anything of interest though. We don't have to reseal it if it was the wrong thing to do?

Thanks again lovely people

 

[Lenny HB]

The aluminum strip on the outside, the roof & side panels will be joined under it and that is the most likely point of water ingress.

You as letting the side down Helen everyone knows Hymers don't leak.

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[3874helen]

Hahaha @Lenny HB of course this is true....maybe I just spilt something one time
So this aluminium strip...it looks like there has been damage along there before and it has been resealed...maybe our culprit! Is it simple enough to take off??
Thanks again, I just love this forum, maybe one day I'll be able to offer some advice the other way.....one day hahah

 

[Lenny HB]

Go gently at it preferably on a warm day so the sealant is soft. Be careful around the screw holes gently ease it with a paint scraper or similar.
Hopefully you have found the source and looks like you can't blam Hymer for it.

 

[Wagoneer]

I had a 2002 BC 544. The only leak we had in the kitchen area was from the high level brake light unit.

I ran a bead of silicone sealant around the unit to seal the interface between bodywork and unit. This cured the leak.

Possibly not related to your problem but something to be aware of.

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[3874helen]

So the corner strip is on its way off....just wanting to confirm @Lenny HB is bathroom sealant ok to use to seal it all up again? Or are we being daft?
We've sealed already around the break light and the extractor fan and all looking good there so hopefully narrowed down to the corner strip, I hope. Thanks again everyone, will let you know how we get on

 

[Lenny HB]

So the corner strip is on its way off....just wanting to confirm @Lenny HB is bathroom sealant ok to use to seal it all up again? Or are we being daft?
We've sealed already around the break light and the extractor fan and all looking good there so hopefully narrowed down to the corner strip, I hope. Thanks again everyone, will let you know how we get on

Yes, you are being daft.
You never want to use silicon when sealing a motorhome joint you need to use a polyurethane sealant made for the job as the expansion of aluminum is quite large under varying temperatures.
I believe Hymer use a Korapur sealant and there are suitable Sikaflex ones, you need to use the correct one as some set hard with little expansion and these are not suitable.

 

[CazPaul]

Hodgsons seamseal cv I would use, non setting. I have fitted a few roof lights with it.

Paul.

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[Manic]

Or Geocel ,The Works from screwfix or Wickes.

 

[Shrimp]

Looking at the outside photos-I don't like the look of that top corner & down the rear edge, personally I would get rid of all that old messy looking sealant, clean it all properly and reseal.
Use a proper cleaner and a sealant for the job, no cheap nasties!
We had some joints looking like that on a caravan-yuk-once and it leaked like a strainer!

 

[3874helen]

Cheers guys, the closest motorhome shops are both shut today and are both shut tomorrow too, nooooo. So I've been onto screwfix.EU and will get one of their flexible polyurethane sealant+adhesive. We're feeling a little stupid... 2-3 days delivery and rain forecast Tuesday, oops. Going to try and cover it up until we get the delivery. Cheers all

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[3874helen]

Hi all, bit of a delay getting the mastic stuff, ended up with sikaflex 512 just got it this morning. Just finished the corner. Opened up a little plate to reseal (at the bottom of the fridge). So the max damp in there is 10%...but seems to be some historic wet in there as the wood that looks to be peeling is all soft and a bit crumbly . How would I know if this is rot? I've attached some pics. Any advice or is this normal because of the big vent under the camper there?

 

[sallylillian]

Yes, you are being daft.
You never want to use silicon when sealing a motorhome joint you need to use a polyurethane sealant made for the job as the expansion of aluminum is quite large under varying temperatures.
I believe Hymer use a Korapur sealant and there are suitable Sikaflex ones, you need to use the correct one as some set hard with little expansion and these are not suitable.

Lenny, I would like to understand the basis of your advice here. Polyurethane degrades within 5-10 years especially with high UV exposure whereas silicone does not, as I understand it, so on an exterior joint one has built in failure.

 

[funflair]

Hi all, bit of a delay getting the mastic stuff, ended up with sikaflex 512 just got it this morning. Just finished the corner. Opened up a little plate to reseal (at the bottom of the fridge). So the max damp in there is 10%...but seems to be some historic wet in there as the wood that looks to be peeling is all soft and a bit crumbly . How would I know if this is rot? I've attached some pics. Any advice or is this normal because of the big vent under the camper there?

It looks to me like the plate you have taken off is a service hatch for the fridge, if you put this back on with Sikaflex 512 which is a PU adhesive it will not come off again without a lot of chew, it would be much better with a non setting mastic.

Martin

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[gus-lopez]

Hi all, bit of a delay getting the mastic stuff, ended up with sikaflex 512 just got it this morning. Just finished the corner. Opened up a little plate to reseal (at the bottom of the fridge). So the max damp in there is 10%...but seems to be some historic wet in there as the wood that looks to be peeling is all soft and a bit crumbly . How would I know if this is rot? I've attached some pics. Any advice or is this normal because of the big vent under the camper there?

No it doesn't appear to be rot that is just the plywood upper & lower sealed surface parting company due to the exposed end. If it is dry you can stick it back with some type of contact adhesive & paint over end to prevent any more ingress of water.

 

[3874helen]

Cheers Martin, we were more worried if it was a sign of rot of not the wood under the fridge? Unfortunately we've already resealed it with the sikaflex, doh hahah may be creating ourselves future work, oops. Thanks Helen

 

[3874helen]

Lovely thanks @gus-lopez, all sealed back, hopefully she's good as new.
Thanks everyone for all of your help and advice again! We are really happy that we've sorted it with relatively few hiccups....so now to see how she fairs in tomorrows forecast 70km gales and rain storm, fingers crossed. This site and the users have been a brilliant help yet again. Cheers all, happy Saturday x

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[Lenny HB]

Lenny, I would like to understand the basis of your advice here. Polyurethane degrades within 5-10 years especially with high UV exposure whereas silicone does not, as I understand it, so on an exterior joint one has built in failure.

Manufacturers used to use butyl mastics which tended to degrade UV they now use the PU's, silicon does not have the expansion properties of the PU and aluminum panels expand and contract significantly under varying temperatures, you only need to look at the side of an aluminum skinned van on a bright sunny hot day. Under these conditions silicon will pull away from the surface leaving an unsealed joint.
I was recommending what the manufacturers use and there are plenty of 20+ year old Hymer's and N&B's sealed with PU that don't leak, obviously you do need to get the correct grade of PU to ensure the life of the joint is satisfactory. In the days of Butyl they used to recommend resealing all the joints every 3 years.

 

[sallylillian]

Manufacturers used to use butyl mastics which tended to degrade UV they now use the PU's, silicon does not have the expansion properties of the PU and aluminum panels expand and contract significantly under varying temperatures, you only need to look at the side of an aluminum skinned van on a bright sunny hot day. Under these conditions silicon will pull away from the surface leaving an unsealed joint.
I was recommending what the manufacturers use and there are plenty of 20+ year old Hymer's and N&B's sealed with PU that don't leak, obviously you do need to get the correct grade of PU to ensure the life of the joint is satisfactory. In the days of Butyl they used to recommend resealing all the joints every 3 years.

That's interesting, I have a mix of aluminium and GRP panels both painted and with a silver coloured sealant where they meet, I will try and see the amount of expansion, when the sun comes out again!

 

[3874helen]

I agree with @Lenny HB , we think we've pin pointed that ours was leaking at the corner joint... a point where it looks to have been damaged before, there was different coloured mastic there. The panels had opened a good bit further than other points once we opened it up there too. We've taken off all of the old stuff, cleaned her up, resealed and hopefully jobs a good one. Regarding the other corners, do you recommend opening those up another day to reseal with her being 17 years old? Hard to tell if we have issues on the other back corner with the shower until being there haha. Sorry for all of the questions
Cheers Helen

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[Lenny HB]

That's interesting, I have a mix of aluminium and GRP panels both painted and with a silver coloured sealant where they meet, I will try and see the amount of expansion, when the sun comes out again!

Beautiful sunny day here.
It is surprising how big the expansion is, our first Hymer had the Hartal door with the triple locking, it was a fine art to get it adjusted so it worked fine on both a cold day and in sunshine at 35 deg.

 

[Theonlysue]

Is its windy, the flame may keep blowing out.
Next time it happens, try parking the van round the opposite way.
Also, when it's very sunny, I try and park so the fridge is in the shade. Doesn't work as hard and uses less gas.

 

[Lenny HB]

Hi all, bit of a delay getting the mastic stuff, ended up with sikaflex 512 just got it this morning. Just finished the corner. Opened up a little plate to reseal (at the bottom of the fridge). So the max damp in there is 10%...but seems to be some historic wet in there as the wood that looks to be peeling is all soft and a bit crumbly . How would I know if this is rot? I've attached some pics. Any advice or is this normal because of the big vent under the camper there?

Just to add my bit, it's not damp as such but the timber has been exposed to water and it has been saturated in the past. The van has probably been stored with that vent facing the prevailing weather. I always use vent covers on the vents when the van is not in use, may be worth investing in a pair.

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