# Sealing roof from water seepage in snow



## Cordyline (Dec 21, 2007)

I'm sure the question has been asked and answered before, but I can't find it so...

We have a Sprinter conversion that we have taken to the Alps for the last three winters and heading down there again in January (albeit it to stay in a chalet, not the van this time!).

There's no problem with leaking in 'normal' conditions but if we don't clear the snow from the roof the melt/re-freeze water seeps in and has caused staining on the ceiling.

We want to seal the joins in the roof before we go and any more damage is caused. Can anyone recommend the right 'stuff' to do the job please? I guess it needs to be fairly quick-drying considering the wet weather we're having.

Thanks in advance


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## TDG (May 26, 2009)

Cordyline said:


> Can anyone recommend the right 'stuff' to do the job please? I guess it needs to be fairly quick-drying considering the wet weather we're having....


*Sikaflex 221* would probably be as good as any sealant or you could use *Sikaflex 512* if you feel the need for a sealant that also gives excellent bond strength to a joint  
In either case, dig out as much of the existing sealant as possible.
As with most of these products, the curing time is very much influenced by temperature and I would be more concerned about that than the wet as you can always protect the area with wammy tape to keep it dry :wink:


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## artona (Jan 19, 2006)

Hi

There is sikaflex as said but there is also a bedding mastic that is used for putting windows in and sealing panels.

I would call Magnums of Grimsby, they stock all these items. I would then get myself one of those very powerful torches. Set up your ladders during the day and do a test run for safety and then at night in th edark one of you get up on top and shine the torch at the roof from inside. Mark where you can see the light coming through to identify the leak areas.

When you come to fill the leak areas intitially at this time of the year use a hair dryer or a paint stripper hot gun (carefully, do not strip the van's paint) and warm the panels to help the mastic bond.

The bedding mastic is sorted as soon as you put it on, the sikaflex will take a while to dry

stew


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## MikeHol (Apr 12, 2008)

All the roof vents that I have seen have built in venting,to promote air circulation, so I would suspect that this might be the source of Codylines water ingress problem.
Normal rainy conditions wouldn't cause this, but snow on the roof might, especially if some of it is melted by warm air escaping through the built in air circulation system.
As to rectifying the cause, I would only advise that covering any ventilation could well be dangerous, so take great care.


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## Cordyline (Dec 21, 2007)

Thanks for your suggestions. Alongside being lazy I'm a bit wary of making a tiny problem worse if I was to start scraping out all the old sealant. If we just clear big snowfalls before thaw/freeze there's no problem - and we won't be staying in the van this year so won't be have the added issue of heating the roof from inside only for it to freeze again during the night.

I was kind of hoping there was something magical that I could just paint on and it would fill any holes it found. That'll teach me for imaging there's a simple solution!

Dare I ask - can I use sikaflex WITHOUT getting all of the original sealant out?


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## artona (Jan 19, 2006)

if you have something that is lose, i.e. the old sealent then to seal over it there is every chance it will all just fall out


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## TDG (May 26, 2009)

Cordyline said:


> ...Dare I ask - can I use sikaflex WITHOUT getting all of the original sealant out?


Yes if you have to :wink: - provided you provide a good bead of sealant over the required area but, be warned, Sikaflex will stick to almost anything, especially your hands :roll: so have lots of rags handy and mask off the areas either side of where you want the bead of sealant to be.


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## rosalan (Aug 24, 2009)

Just a thought. If it only leaks when snow is in the roof, and it is a panel van, could the problem be condensation? Cold snow, sitting on metal with a warm damp interior would be the ideal environment to generate quantities of condensed water.
Alan


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## Cordyline (Dec 21, 2007)

Thanks all for your advice and tips. As usual I'm glad I asked before forging ahead and getting it wrong.

As it's only an occasional problem that can be avoided by clearing snowfall before freeze/thaw I think a little extra sealant is all that's needed right now (once I've checked that the old stuff isn't about to fall straight out ) - sikaflex sounds like serious stuff so will make sure I'm prepared and equipped before tackling it!

Thanks again


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## rosalan (Aug 24, 2009)

Do not worry about Sikaflex, it is easy to use and provided it is applied to a dry surface, should fix any leaks.
I have had a fairly extensive read concerning your problem which looks ever more like a lack of air-seal or lack of ventilation generated damp, which can and will drip. I also gather that this problem is associated with a few specific models but I am sure that by now you too will have discovered all of that. So good luck with whatever solution you decide upon.
Alan


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## wooly (Oct 3, 2007)

Hi I would agree with Rosalan, before you make things worse, are you absolutely sure it is not condensation? Having a sprinter conversion ourselves, I think this is a far more likely cause.
Michael


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