Hi AbbeyOwner, It is not necessary to use any form of mastic on the roof seal, this is why the fitting instructions don't mention it. For all correct information on Vision Plus / Status products contact Clint or Harvey at Grade UK ON 0115 986 7151.
Hi Terry, my advice would be to contact the manufacturer (Grade UK)on 0115 986 7151, ask for Clint or Harvey - Technical / Customer Service,they will point you in the right direction.