Repairing cracks in roof

[Cragger81]

Hello all -

I've just recently purchased a Mk8 highroof transit for campervan conversion and have discovered a couple of rust points on the roof (looking from inside) which appear to be cracked right the way through the roof panel. The roof has clearly received a bit of abuse as some of the support struts have come away from the roof panel itself in places. What would be my best approach to getting a good repair job done on this considering I'll be inulating and cladding from the inside so obv can't afford any leaks whatsoever?

I'm looking at rust treatment products such as FE 123 https://www.rust.co.uk/product/cat/fe-123-rust-converter-10 but am unsure whether this is the best approach considering the cracks break right through the panel and therefore may need to take more drastic action eg cutting and welding.

Any advice much appreciated.

[dumper]

Have you looked on top of the roof if it is a crack I’d expect it to be all the way through are you sure it’s not just the paint clean the paint off the inside to see if it is . If it’s not cracked re paint it and waxoil it on all my conversion I have waxoiled them everywhere inside before panelling them only down side of doing this is the smell taking a while to clear.

[Cragger81]

Hi Dumper -

Thanks for the reply. Yes I've scraped away the paint from around the rust area - from the inside it certainly looks like a couple of the cracks break through but then the roof has been externally coated with something - quite a thick white acrylic paint possibly rubber paint? My worry is that there was definitely moisture on the inside when I removed the cladding so whatever has been put on the outside isn't doing it's job.

Re waxoil (hammerite stuff I assume?); do you apply this to the whole van interior or just 'suspect' areas? And do you apply straight onto rust or is there a pre treatment process?

Thanks

[dumper]

It’s the liquid wax oil I’ve sprayed on to stop rust if it’s had something painted on the outside to seal it you’re probably going to have to clean it off and weld it or is it somewhere you can fit a roof vent .thats trouble with buying a hightop van you never look on top for damage when I got my mk6 jumbo home I found it had been driven under something but luckily it had not gone through.