# Sealing exterior joints.



## jhelm (Feb 9, 2008)

I just noticed a slight bit of moisture above the over-cab bed. I covered up the roof and took off the molding that covers the interior joint. There is very little damage, one has too look hard to find it, and now I'm drying it with a small heater.

While it was still under warranty we had something similar in the back which was fixed by the dealer. However, I was not so happy with the way he did it and I think I could do a better job myself. He also told us that every few years all the joints should be resealed. I'm wondering how this is done. Seems the only really sound way would be to remove all the joints covers and replace them but I doubt anyone does this. What is the normal process? I'm guessing caulking applied along the edges.


----------



## ovalball (Sep 10, 2008)

Are you sure this isn't just condensation?I often get it when it's really cold outside and we have had the van heating on.Just a thought.


----------



## jhelm (Feb 9, 2008)

I was wondering that myself. Especially with the two kids sleeping up there. I took off the molding strip and pulled the ceiling material open a bit and there was moisture inside. It's all dried up now, after I left an electric heater on for a while. The problem is that this is right under the joint on top of the roof. It's raining here now so I can't check the roof, which I also have covered up for now.


----------



## trackerman (Aug 16, 2005)

As a matter of interest what do members (and the professionals that contribute to this forum) recommend for resealing exterior joints?

Stuart


----------



## jedi (Nov 22, 2007)

Hi,

Silkaflex is the brand I've most heard mentioned. If you search MHF you will find mention of it.

Interested myself as I had water ingress from roof on driver's side repaired under warranty. He dug out old sealant and replaced it. I fear I now have same problem on other side.

This I will tackle myself so will follow this thread for advice/ideas.

Jed


----------



## jhelm (Feb 9, 2008)

jedi said:


> Hi,
> 
> Silkaflex is the brand I've most heard mentioned. If you search MHF you will find mention of it.
> 
> ...


On my van the joints are sealed originally with a rubber type gasket under an aluminum molding strip, which I think must be the common way. If there is sealant it would be under this strip. I don't think it would be wise to mess with that installation so it seems that putting sealant around the edges is the typical solution. But that is also my question, is that how it's usually done?


----------



## maddie (Jan 4, 2006)

Hi firstly you need to know what material you want to seal,and get the appropriate sealant.
Sikaflex type is good on most materials eg.ali to ali
but no good on plastic.For this you need a non setting gp mastic or "caravan seal"
If you feel confident about the job then removal clean,reseal and replace is the best way to go ,
after that it is masking tape and seal down the edges smoothing off with a wet finger before removing tape.
terry


----------



## slaphead (May 14, 2005)

*joint sealing*

sikaflex....sikaflex...cant beat it...buy from motorhome dealer or boat chandlery.. :wink: :lol:


----------



## barrypat (May 6, 2006)

*sealing*

Hi Jhelm, I did some work on my C.I. last year, it sounds like your description of construction i.e rubber moulding then an aluminium capping is the same. Under that rubber moulding will be very sticky non setting sealant, i dont know the age of your van but mine was thirteen years old, I suppose the sealant could start to dry out in time but I was suprised just how good the sealant was, if it proves to be a leak you have I would not recommend just sealing the edges, i think this would only be a temporary solution, once water has made an ingress the only sure remedy is to remove the seals clean off the old sealant and start again with new, a very messy and time consuming job.
The reason I started workind on the C.I was not because I had a leak, I noticed that under the thin rubber capping that covers the screws that retain the aluminium capping, there was a 'lump' every few inches, I carefully pulled a short section of the capping out and discovered that the screws had started to corrode, this was causing the bulge under the capping, I decided to remove the whole strip covering the screws and was shocked to see how much water was trapped under it, this was obviously the cause of the rusty screws, I replaced every screw on the van after this discovery with stainless steel screws, some of the original screws were to badly corroded to be removed so I drilled another hole as close as possible and put another screw in, I smeared non setting caravan sealing compound on every screw first then fitted a new capping strip, I doubt you could reuse the old one as it tends to get hard with age. After doing all this work I have since exchanged the van so someone else will be benefitting from allmy hard work.
After discovering this weak point in the vans construction I found myself looking at this potential problem on other vans seen for sale at shows, it was obvious that this is a widespread problem, I was surprised to see it on Hymers. Stainles steel screws are not expensive I think it was less than £10 to replace all the screws, on vans costing many thousands it seems like penny pinching to me I doubt that boat builders would use anything else but stainless.
Sorry if this reply has gone on a bit but I think its helpfull to get as many veiws as you can with all our problems.

Barry


----------



## jhelm (Feb 9, 2008)

Barry, what you describe is exactly what I am seeing. I am just now dealing with the strip that goes across the top near the front. The plastic cap strip slides off easily and I have found screws that are rusted. I think I will remove it and seal underneath then put it all back together. On the corner moldings I think I will just seal the edges. But will probably wait until the weather drys out.


----------



## patman (Jan 1, 2007)

There have been good reports for Captain Tolleys Creaping Crack Cure.
I used it myself as a precaution on the seals on my van. It dries invisible and is very thin so it gets absorbed into cracks.

Regards Patman


----------



## gaspode (May 9, 2005)

Make sure you use the correct grade of Sikaflex, it's 512 you need for re-sealing joints.


----------

