I am more then happy to check the roof sealants every 12 months to ensure that the seal is still good, but when the van is only just short of 3 months old, I am a little concerned! I have sealed it up now, and I am pretty happy with the seal that I now have, but will check it every April to ensure no more water leaks! Have used sikaflex on the roof, not fused if it alters the paint up in the centre of the roof as I don't know anyone tall enough to see there, but I will definately keep that in mind for areas where people will see it!