Eternabond as preventative measure?

[Pageant]

Dear all,

 

We’ve just paid a small fortune to repair a very well hidden damp problem that didn’t get picked up in our pre-purchase report from an NCC approved engineer, when we purchased in Spring 2019. Annoying, but that’s life - we love the motorhome nonetheless and got it for a decent enough price, so could have been a lot worse...

 

Anyway, we’ve had the structural repair done but only a temporary fix done to the damp entry point as the structural work was more extensive than expected - and the garage ran out of time to do the rebedding of the suspect joint before we needed to pick up for holiday, so they attended to a particularly suspect section with a bit of sealant pending a more permanent fix. The suspect seal is the one going across the front above the windscreen, joining front panel to the roof - it’s an A class Eura Mobil of 2002 vintage.

 

There are no other obvious issues with the roof joint but the motorhome is getting on now and I wondered if preventative measures might help us keep it that way. I’m loathe to rip apart and reseal joints that aren’t obviously causing a problem, but wondered if Eternabond would be a good idea along the roof/side wall junction. It wouldn’t be too visible up there - I had in mind to lap it over the top cover strip which my finger is pointing to in the photo I’m hoping to attach, taking it a couple of cm down the outside and lapping over on to the main roof the other side by a couple of cm. But have some concerns - might it cause more problems if/when it fails? It’s piggish to remove by all accounts. And some have raised concerns about it looking like there’s a problem with the van when it comes to selling. However, we’ve always gone in for servicing and damp checks at least annually, so would have thought the reassuring absence of a damp problem should be comforting? Of course, I also know from bitter experience that reports and clear damp checks can only be so reassuring. However, I think we were unlucky - there were subtle clues that were picked up by our servicing garage (which is admittedly fastidious), but would, now that we know, have expected to have been been flagged for further investigation by a NCC-approved engineer being paid to specifically look for issues pre-purchase.

 

Any thoughts/experiences of Eternabond as a preventative measure where it won’t show too much? We love the motorhome and want to hang on to him for a few years but, realistically, there’s only so much money it makes economic sense to shell out on doing preventative resealing - or time I’ve got to do it myself (at least those jobs I feel vaguely competent to tackle myself - re-bedding a skylight or something similar is about my limit...). We’ll trade him in for something newer at some point, but this is our first motorhome since making the conversion from caravans and would like to keep him in decent shape for a few years to come, making all our newbie mistakes on him, before moving on to something newer. I should say that, apart from a more minor damp issue we did know about when we bought him - traced to an entry point behind the rear bumper which we had fixed - he’s been solid, everything works really well and feels really robust.

 

I’m just so impressed with people’s technical knowledge on these forums, so would very much welcome all thoughts and suggestions.

 

Thanks v much

 

 

[BruceM]

I’ve not used or come across Eternabond before so looked it up and came across this video which may or may not influence your use of it

. It does make me wonder why it would be used instead of good quality sealant. Incidentally, I’m not impressed by the video makers final sealant finish . Practical, yes, but still, it might have been smoothed a little more despite only being visible to someone on the roof.

[Pageant]

Thanks very much Bruce - yes, it’s the wildly fluctuating views about the product that made me wonder. Some extol it’s virtues whilst others are much less enthusiastic. The reason for using it instead of a good sealant is because, as a preventative measure, I’m loathe to disturb a (currently) sound enough joint, but recognise it may degrade in future. And, of course, it’s a much quicker application since you’re not removing What’s already there - just cleaning and prepping the surface. But the video does highlight the concerns, even as a preventative measure, I guess...

[Derek Uzzell]

Pageant

 

Welcome to the Out&AboutLive forums.

 

Eternabond tape was mentioned on this forum in the following threads (in descending date order)

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Sealant-for-the-roof/46990/

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Sikaflex-512/47026/

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Roof-joint-sealing/32906/

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Solar-panel-Can-it-be-removed-/8338/

 

and in 2017 on this forum

 

https://www.caravantalk.co.uk/community/topic/121226-eternabond-tape-the-end-of-leaks-forever/#comments

 

I can’t see using Eternabond tape to ‘overlay’ a currently-waterproof joint as a preventive measure doing any harm, though (as was said in your original posting) if the tape were still in place when you came to sell the motorhome, it would definitely deter any prospective buyer.

 

Although using Eternabond tape is clearly popular in the USA RV marketplace, I’m doubtful you’ll get much ‘hands on’ experience from UK motorhome forums.

 

A possible alternative seems to be 3M’s 4411N Extreme Sealing Tape (example advert here)

 

https://tinyurl.com/y3zwt3ed

 

 

 

 

[Brian Kirby]

In the nicest possible way, sticking tape over a suspect joint is a bodge, not a cure.

 

The van is 18 now years old, and its roof has presumably been exposed to weather and UV light throughout that time. The individual parts of the roof are liable to be of different materials, with different coefficients of expansion, but eve if they are all of the same material, some will have been in full sun while others are in shade, so that differential expansion will have taken place between the elements. All sealants age, and in general, those exposed to UV age fastest. As they age they lose elasticity, and in some cases adhesion, so become prone to crack or detach.

 

You will be hard pressed to know what actual sealants Eura Mobil used when your van was built - though it may be worth asking them. Formulations change over time, and the chemistry of sealants is complex. In addition, some react unfavourably with others. So, the adhesive on the tape may, or may not, react with the existing sealant and may at the extreme destroy it. The tape will hamper any attempts to re-seal the original joints, making that job much more time consuming than would otherwise be the case.

 

If the seals are showing signs of ageing, which you could test with gentle probing to see if it is loose or has hardened, the best remedy would be to get the van under cover and then remove all joint cover pieces/strips, carefully remove all traces of the original sealants, and then re-make all joints with a good quality, elastic, modern building sealant. Something based on "modified polyurethane" should suffice.

 

There is little point in doing this job piecemeal, as the new sealant will terminate against old at the ends of the cover pieces etc - where it may, or may not, successfully bond, possibly leaving routes for water ingress, and will again be disturbed when the next cover piece is done.

 

Also, there is likely to be a set order in which the cover pieces have to be assembled so that a weatherproof seal is maintained between each.

 

If you intend keeping the van for several years, and in view of what you've said, I'd say take it to a specialist caravan repairer and get an estimate to completely re-seal it, taking off, cleaning up, and re-bedding all the cover pieces with a suitable sealant - or, if that seems uneconomical, give it a good external clean and bring forward your intended trade in date!

 

Your worst option would be to delay until further ingress takes place, and then find yourself driven by events with little choice over what to do, and when.

[fjmike]

For once I have to disagree with Brian, as a professional motorhome and caravan valeter I get to see an awful lot of roofs and have noticed several manufacturers are using a product very similar to Eternabond as standard. Applied correctly it can look much better than a sealant filled joint

[Brian Kirby]

Possibly, Mike, but that will be a joint that has - hopefully - been designed to function in that way. My point above relates to joints that were designed (same caveat! :-)) to function when sealed using upstanding cover pieces and sealants. Applying a sealant tape over these is liable to be far more difficult than applying one over a predominantly flat seam. There are too many awkward internal angles, and tape joints, to be formed when trying to tape over protruding three dimensional cover pieces (such as those shown in Pageant's photo), plus the requirement to ensure the tape adheres properly to all affected surfaces, including the existing sealant beddings, to be confident that full weatherproofing has been achieved. It only needs one point of ingress for a seal to have failed.