Sealing High Top to Van Roof

[Marlowe]

Hi all,
Now the weathers dry enough to do some work on the van outside, I thought I would try and change the sealing stuff for the rain gully between high top roof and van roof, if you know what I mean? (The rim is rusting from the inside out due to water getting in the sealant bits that have split)
Anyone have a tip what's the best sealant to use, and tips for applying it.
Thanks
Marlowe

[project25]

Hi, Ive just removed my high top and replaced with a pop top. My high top was held on only with sealant and some one has pumped more silicone from the inside it did not leak. Ive used Sikaflex 512 sealant and adhesive fitting the pop top parts. Silicone does not stick to plastics