Sealing top joints on caravan roof

[SilverSurfer]

Hello, at the moment my caravan is protected by a Protec cover which will be taken off in a few weeks. Over several months last year I became aware of a slight leak with rainwater dripping in on the bottom edge of a rear side window, luckily the staining cleaned off.
I have checked the roof and all seals appear to be intact but obviously there is some point up there where water is getting in. My plan is to use a sealant to bead over the joints all along the seams but out of view from below, ( just above the awning rail).
Can anyone suggest a particular product / type of sealant which will do this job and will last for years?
The caravan is an Avondale.

 

[Parksy]

Hi Silver Surfer
I'd suggest that in order to completely re-seal the joints so that they remain waterproof you may have to remove the awning rails and front / rear joint strips, Click Here for a pictorial guide.
A proprietary brand of butyl mastic non setting sealant which can be bought in tubes and in strip form would do the job. Click Here for a list of sealants and brief descriptions of their uses

 

[Raywood]

If it is dripping in on the bottom edge of the window have you checked the window sealant?

 

[SilverSurfer]

Thanks Ray, yes I have checked all around, what confirms my thoughts are that last year when we were on site with the water coming in during a wet period our awning was fitted to the van. It's just the same when the awnings off.
cheers Tony

 

[Parksy]

http://www.thomson-caravans.co.uk/dampavan/dampavan.htm

As the picture shows, the joint between the roof and the wall of the caravan is actually behind the awning rail and leaks on the side where the awning is held are common.
Removal of the awning rail is not particularly difficult but it's time consuming and care must be taken not to bend the awning rail out of shape or to damage it. Rolls of butyl mastic form strips for the awning rail to bed back on to after the old mastic is removed using a plastic scraper, white spirit and then methylated spirit to remove the greasy residue for a good clean surface.
Seal the fixing holes too and use new stainless steel fixing screws and rubber strip when fixing the rail back on, and smooth off any excess mastic which splurges from the sides of the rail (as it should) with the scraper and white spirit for a nice tidy finish.