How to waterproof a caravan's roof (and what NOT to do)

We have had Zeph at home for 4 weeks now, and in that time we have cleaned her, discovered holes in the floor and rotten wooden. 

Looking at other blogs, I'd say we have got off lightly - yes, we need to replace some of the floor and strip off the inner lining to tackle the rot in the corners, but at least its pretty much in good nick!

All cleaned up

When we cleaned her, I used a steelo pad on the roof - this worked really well as it sanded the roof at the same time. Did I say the exterior panels are aluminium? No risk of any rusting.

The original look

Here are a few photos of the wonderful 70's interior - many memories!. What will she look like when we're done?

The Caravan Man's Advice - that I totally forgot to follow

First job was to find out how to make sure she was water-tight and then paint her.  Youtube was not that helpful for this type of caravan, so I checked if there were any professionals I could ask.  Found an incredibly helpful local guy who restores caravans at Dunedin Motorhomes; he gave me great advice once he realised I was keen to tackle this myself rather than use his excellent services.

The first issue I asked about was how to reseal the seams in the aluminium roof, as someone had previously sealed this with an aluminium tape - it had worked well, but was starting to lift. So I peels this off, and sprayed the old adhesive with 'De-Solv-It' from Mitre 10 before wiping clean with turps.

I then used a 3M product (Extreme Sealing Tape 4412N) to reseal the seams - now this is where I made a mistake. I purchased this from the parts department of the local Toyota dealership. The caravan man had said to apply the seal after re-painting - I thought he said before the repaint. Bummer. 

He later pointed out (let's say I visited caravan man more than once) that it could be removed for the paintjob, but would help ensure the seam was watertight until the painting happened. So that was good news, but he did say it would be a painstaking process to remove. Double bummer. At this stage I'm inclined to leave it on, and paint over it.  Rach pointed out that if the paint comes off the seal (and apparently it will) then no one would see it, given its on the roof.  Hey ho.

How to remove decals

I used a caramel wheel (attached to the drill) to remove all the beautiful yet faded yellow and brown decal stripes and the lettering. I'd never heard of a caramel wheel before. Worked a treat. This was followed by Rach on the sander removing the original paint hidden by the decals.

Waterproofing the exterior

I had asked the caravan man the best way to reseal the aluminium trims. I worked on one side first, going through the following steps:

• remove the trims and nails, along with the old adhesive and any remaining silicon that I'd used year ago (in an earlier attempt to improve the water-tightness - I'd say I failed, since the caravan man had said to use urethane and not silicon when re-sealing).
• The 'De-Solv-It' worked a treated here again, to clean up the walls and the back of the trims.
• Use a white urethane and stainless screws to re-attach the trims. Now you need to do this in steps.  Firstly, use the same nail holes in the trims and walls to drill holes for the screws, and then test the screws through the trims and into the caravan wall to ensure they align and fit. If you don't, you might have a lot of non-fun trying to sort out the screws with the urethane causing a few issues for you.
• Apply a thin smear of urethane over the seams and holes of the caravan that will lie under the trim when in place. 
• Once dry, apply a good amount of urethane to the back of the trims - enough for some excess to squeeze out when screwed into place - and then do just that: screw into place. 
• You may need to apply more urethane along the seams once in place. 
• Use a small piece of wood to act as a scraper for removing excess urethane, followed by turps and a cloth for clean up. 

Apply one trim at a time.

The moment of terror: ROT

With one side of the caravan resealed, we were getting closer to the point that the caravan would be fully water-tight. We had been lucky with a good run of fine weather, and so all was looking up. The caravan man pointed out that if the paint is not flaky (that's us), rub the exterior down with Scotchbrite pads and turps.

I was about to tackle the exterior trims on the other side of the caravan, followed by the final surface prep for painting, - and then Rach found a rotten floor in the kitchen cupboard.  That was the start of a rabbit hole for us.  

The focus was now the interior, as there was no point re-attaching the exterior trims through aluminium panels and into rotten wood. And that's where we still are!