Hello! I found some damp in the caravan, under further inspection and after a bit of research on here I found that the water is coming in along the awning rails where old sealant has corroded. Its an old van maybe 20 years. Sikaflex 221 was recommended by a friend, but I've also seen that mastic roll can be used. I have also seen on Wizard's site that the awning rail was removed, would just sealing along the rail and over the screws be sufficient if I was to not remove the rails? Also, with our fine British weather, do I need to wait for a bone dry day, or can I do this any day under cover. I wasn't sure about moisture in the air affecting the curing. Thank you in advance :)
Lizzy if you can feel the inside soft at all then it is a rail off job, yes it is a pain but any other way is a bosh. the screws will be a pain to remove, the mastic like chewing gum (lost of white spirit and a clean with meths sorts that) use new mastic strip and stainless steel screws, your infil strip will probably be scrap so buy new, tip for fitting it, place in a bucket of hot water to make it softer and easy to insert. then open proscetto
Personally if i am doing repairs i dont bother refitting infill strips as it is an almighty faff. wee blob of sika smoothed round each screw to act as a washer will do the job. the main problem was the manufacturers used mild steel screws that rust and allow the water in, have actually seen glorified panel pins used. totally useless, no wonder the things leak
I personally would take the rail off and do the job properly.
As to sealant its a question of personal choice. I have used both in the past on different caravans but the mastic on a roll I found not as good on rails that have don't have a particularly flat side that screws down to the caravan. On these occasions I used a liquid mastic called Puraflex what is a sealant adhesive similar to Sikaflex but is probably less than half the price and is available from screwfix or toolstation.
One handy tip for getting the mastic off the back the rail is to you use a power drill on slow to pull the mastic out of the indentation. Turn the drill sideways on to the rail and ball up some of the mastic at the end to start it off before putting a large drill bit into the ball. The slow rotation of the drill will pull the mastic out as you move it along the length of the rail.
Thanks guys. It looks like I've got a nice challenge ahead of me, luckily I am on maternity leave so will have time to have things sorted before we go away in August, fingers crossed if the weather improves. Am I right in assuming I will need less humid days to use the sealant?