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Caravan Roof Resealing - Fixed!!

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maweida:
HI All,

Wanted to post about my recent win to fix my leaking caravan roof (yes, i know its a car forum, but most of us are vanners so hope this is useful for you).

My Jayco 16.49-3 Expanda developed a small drip on the joint between the roof (aluminium) and end panel (fibreglass), see photos. Unfortunately it dripped on the wife's sleeping bag... oops so needed to fix it.

The old sealant was quite chauky, and was very dirty (it was done by the original owner, say no more!).

I used a scraper (uses single sided razor blades) with brand new blades to remove the old sealant, it was very easy, just a case of getting the right angle (too steep and the razor wants to cut in to the fibreglass, too shallow and you'll leave some sealant behind). The painted surface did not scratch.

The difficult part was the 4mm rebated gap that i couldn't fit the razor blade in (see photos). I spend hours trying to remove it. Then i thought about making my own scraper, so used the angle grinder to cut a razor to 4mm wide to fit in the gap, this worked really well and removed all the sealant very quickly.

Next used sand paper (280grit) to remove any residual sealant and also to lightly scratch up the surface to allow a good bond.

Next i used 90% Ethanol (my local chemist provided a small bottle) to dissolve any old sealant and clean the joint.  I think any non residue alcohol will do the job (ie Isopropol, Metho, etc).

I was worried about leaving any residue, so gave the surface a light sand, then brushed the dust way.

Next i masked the area, since the join has 2 x different materials (different expansion rates), i decided to have a nice cap shape to the bead (see last photo), to allow greater flexibility (the wider the sealant, the higher the expansion allowable).

I made up a profile tool, using a old take way container (clear rectangle ones from the Chinese restaurant), and cut a nice radius using tin snips.

I used Sikaflex 221 (Bunnings), and filled up the joint, i used my finger to push up and down (pumping) along the seal to make the sealant stick to everything. I then used the profile tool to achieve the final shape.

Next was to get a spray bottle, with 30% dishwashing fluid (balance water), and spray the Sika, and your finger, and wipe along the seal. Since your finger won't stick, the Sika surface will become silky smooth and dirt won't stick down the track.

Next remove the masking tape, and use the dishwashing solution to blend any edges that have a lip from the masking tape. Note: The Sika won't stick where the dishwashing fluid is.

Waited 3 days for curing. NO leaks!!! and $29 bucks!  Hooray, now to book the next holiday down the coast!

see a few posts down for more info!










JS:
That’s a fine job you’ve done there. Your attention to detail should pay off with no more leaking and a much better looking van.
Now , if the rain stops, you’ll be able to enjoy your camping again.
Cheers
Jim

maweida:
Thanks Jim!
A bit more on this. So i got thinking that if I needed to do some small repairs (leak) down the track, would it be possible to bond new Sika to old Sika. I don't want to redo the entire joint, if only a small area was leaking (don't want to create new leaks, where there isn't a leak at present!).

Anyway, I did some testing, applied Sika 221 to a sanded/painted/aluminium trim and it stuck really well, waited 2 days, then applied Sika 221 again. It stuck very well. I did try cleaning the old Sika with Isopropyl but it didn't stick as well as untreated Sika,

Good news, if the old Sika is clean, it seems possible to do localised repairs without having to redo the entire seal.

Aaron S:
Silicon sticks to silicon as a general rule.

Excellent work on the repair.

Ian G:
 Yes good job, it's all about the preparation. Sika 221 isn't silicon, you should be ok recoating if the sika is relatively new but if it has weathered for a couple of years I'd do what you have done. Sika has a good technical advice line that will give you all the info that you need

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