Hi i used some off this stuff on the horse box you can get it at good builders mer or off flee bay dam good stuff
http://thumbs1.ebaystatic.com/m/mYIngmUkeNCzsosUQKFc09w/140.jpg
The No.1 Caravan Sealant - Industry Choice
Ideal for Caravan and Motorhome manufacture and repair
Cures on exposure to atmospheric moisture to form a
durable elastomer of high adhesive strength
SIKAFLEX 221 - 300ML BLACK
Single part polyurethane adhesive sealant.
The professionals choice. Use to bond on roofs, panels, battens, doors, anything requiring bonding or sealing to anything else.
Widely used on solar panel installations. All directly bonded windows and windscreens use Sikaflex.
Full bond after a few hours, flexible & resistant to aging and weathering, over-paintable gives a very strong bond.