Sikaflex 522 is also suitable for the replacement of joints on both caravan marine and other vehicular construction projects. Very easy to use but doesn't seem flexible enough to me and may not fill the gap completely although several users appear to be satisfied. Sikaflex 512 has now been replaced by 522 - the sealant is exactly the same but just an updated version. I look forward to other comments, agreeing or otherwise, arriving soon (hopefully they will provide links to various sources which give examples of jobs that have been done...

Sika Sikaflex | Sikaflex EBT | Screwfix Sika Sikaflex | Sikaflex EBT | Screwfix

This multipurpose adhesive sealant from SikaFlex is ideal for caravan and motorhome construction and repair. It bonds to a wide variety of surfaces and is perfect for those wishing to create permanent elastic seals of high adhesive strength. This approach seems best, as you can put plenty on, smooth it over with normal tools before it skins plus it remains plastic over time (supposedly) ?