damp

[fizzy]

Hi

After a bit of advice please.
Recent caravan service indicated damp readings of 20% at back end top corners.
Engineer suggested might be seals on the roof.
There is a rail/bar thing (sorry not sure of proper term!) about a foot in from the back that goes across the roof & the seals do look a bit shabby. Would this be an easy thing to do ourselves, I assume take of rail/bar thingy clean it up re-seal & stick it back on?
Also would we need to do anything internally at that level?

Hoping you are all better informed than me

 

[Damian]

You don't say what make of van you have, it would help.
However, damp where you describe usually is due to ingress from the roof strap (the bar as you say) and it needs removing, all old mastic removed from it and the van then resealed with Soudall Fixall or Sikaflex 512 and the screws covered with mastic after fitting.

Yes it is something you can do yourself, just take your time.

 

[fizzy]

thank you for replying

Sorry, its an Avondale argente, 10 yrs old

When would you use the 'strip' sealants on a caravan? Not doubting your recommendation just been doing lots of reading & getting very confused by all the products available for sealing, sticking, fixing............ !!
I know the husband is going to want to have a go at this himself. As we dont have anywhere to work undercover, we would have to do it over a dry weekend (assuming we ever get one!) do you think that's realistic?
Also seem to be differing views on weather to re-do seals on the awning rails etc every so many years or to leave well alone unless moisture reading go up - again v confusing :S Really interested to hear the views please.

 

[Gagakev]

Follow Damiens advice and use the tube mastic's, regarding resealing the strap rails...if it aint broke why fix it.
I have resealed awning rails and it is very labour intensive and a real bind, took me 22 hours to clean one rail!!
And I still had the van to clean!!
When you reseal any thing make sure you clean every thing off, new mastic doesnt like old mastic.

 

[swpostie]

Hi Fizzy

The tube sealants such as Sikaflex 512 are generally considered to be far superior to the old fashioned strip mastics - better sealing and longer lasting as they stay flexible.

 

[fizzy]

Thank you.

 

[Damian]

Quote " When would you use the 'strip' sealants on a caravan? Not doubting your recommendation just been doing lots of reading & getting very confused by all the products available for sealing, sticking, fixing............ !! "

In all the time I spent as a NCC Approved Workshop I never used strip mastic on any van I did work on as it is , in my opinion, not the best thing to use.

The gun applied tube mastic is much better as it is more reliable and easier to use
With strip mastic as you put a screw into it, it winds around the screw thread and creates voids where you cannot see them. This does not happen with gun applied mastic so you get an even , full seal and as long as you put a good bead of mastic on whatever you are sealing it is easier to get a good seal as seen when the mastic squeezes out along the edges, then tooled off to provide a neat finish.

For items not usually removed, such as roof straps, awning rails and such like, a sealing/bonding mastic is best , such as Soudall Fixall or Sikaflex 512.
For items which may need to be removed, such as rooflights if damaged, then non setting mastic is preferred, such as IDL99.

As for doing the job over a dry weekend, yes it is easily done, the longest bit is removing the strap and cleaning it and the van , the reseal is very quick !!

 

[Gagakev]

Thank you.

Thank you for the Thank you, always nice when the folk on here are acknowledge.

 

[fizzy]

Thanks to all of you for such fast & knowledgeable replies, I feel a lot better informed than I did a few hours ago and can now give the husband his instructions
1 last question, hopefully we will be able to have a go at this next week end (weather permitting) but in the interim is it worth putting any tape of some kind over the roof strap to try & stop any more water getting in or is that likely to achieve nothing more than extra sticky stuff to remove!!

 

[Damian]

It would not hurt to try and stop more water getting in, and will only cause minor extra cleaning.
It is also worth looking carefully at the panels where they join when doing the job and check for any splits in the plastic .
When removing the roof strap, use plastic scrapers to remove old mastic and white spirit to remove the remains, then just before applying the new mastic use methylated spirit to remove any oily residue from the white spirit

 

[Sproket]

I use these for removing sealant they don't damage the paintwork

 

[fizzy]

I have today ordered the kit you've recommended, got the gaffer tape out & slapped that on as rain is forecast here tonight , looking forward to getting this sorted out now! Thanks again