Roof leaks

[mcbutler]

Hi all,
Firstly as a new tranny owner I am really grateful for all the help offered by you al in my recent posts

Ok, 2014 Jumbo model.

Converting to camper, after all this rain i noticed some staining on newly installed wood panel, upon removal it appears the leak is on the drivers side
of the van at the exteral junction of two panels at the roof corner. It coincides with one of the internal roof cross pieces.
Can anyone recommend a sealant that will actually work on the outside of the van as I know DIY store silicones are pretty useless outside.

Over to you guys and thanks again...

Mark - Plymouth

[Sam123]

The leak will likely be from the plugs which cover the roof rack mounting bolt holes. Best thing to do is remove the plugs, then reinstall with some sealant. Sika sealants are good, something like ebt, which I think is UV resistant, but check that. Only issue is, if you use a combined sealant and adhesive, you may struggle to remove the plugs if you want to fit a roof rack later. So if a roof rack is in the plan, then just use a silicon sealant, not adhesive-sealant.

[Altransit]

You need a proper automotive sealant such as Upol Tiger Seal, or similar non-silicone based sealant.

You shouldn't use silicone on vehicle metal panels as it's very corrosive

[mcbutler]

Thanks everyone,

Interesting info ref silicone on steel panels, good to know

[Willber37]

Ideally you want to use something UV proof based. I use anything 'Sika' and vouch for how good they are.

Something like Sika 521-UV on it's own : https://www.uksealants.co.uk/sikaflex-521-uv.html

With regards to your conversion : When you attach anything like a roof fan or solar brackets the sika will get the job done.. but make sure you use in conjunction with a sika primer too.. Stuff aint going nowhere then!

Some of the mk8 roof holes can leak as said, mine haven't depends on state of roof.

BTW : some of the roof rack mounting holes can be miss-aligned with the internal threading just Dremel them out wider and prime taking care of surrounding roof area.

Good-Luck!

[mcbutler]

Found it, a tiny 1mm hole in the sealant at the junction of the two side panels and the roof.
I had to poke around gently and noticed a blob of black water pop out from under the sealant.
I lofted the edge, poked some tissue in and left it to capillary drain and dry it, tiny 'blob' of sikaflex and the jobs a good un....

With ref to silicone on metal, that only applies to galvanised material - apparently.....

Thanks for all the advice

[Willber37]

Nicely done! Yep.. That's all it takes, I had the very slightest of bumps in the rubber pad that went under the roof rack towers.. We're talking less than 1mm and water soon finds its way through.