Water Ingress Spongy Ceiling

PaulandOla · Apr 3, 2015

We have just bought a second hand Fiat Ducato Auto-Roller motorhome, 1997/98 reg. We paid a very good price for it, but we knew there was water damage on the ceiling, I checked the floors and walls are they appear to be ok, (not spongy) I have just started removing the roof light to inspect and see how bad it exactly is. And its pretty bad, it looks like its been leaking around the roof light for quite some time.

I am looking for some advice on how best to tackle this, I have removed the lights. and the roof light. I thought I would take down all the ceiling as far as the cab as it appears dry there. cut a straight edge where I can join the new ceiling and old. I'm guessing all the insulation will have had it and need replacing. Then replacing the ceiling panels, I've been looking where you can buy these from for the proper motorhome ones. I am also thinking of upgrading the lighting to LED downlighters while I have the ceiling down.
Which is the best insulation to use? and sealant to use? I have been researching the different ones Silkaflex 220 & 512 also Everbuild Stixall extreme power - this is their description of the product "Hybrid PMS polymer technology. Combined building adhesive and sealant, bonds and seals virtually everything to anything. Water resistant, can be applied to wet surfaces"
Also Everbuild Puraflex 40 "Premium quality one-part high modulus polyurethane sealant and adhesive that provides exceptional resistance to mechanical wear. Used in the engineering, caravan and marine industries and for sealing floor joints in ceramic installations that are subject to high traffic. Excellent chemical resistance"
These are half the price of Silkaflex 512, I've heard some people using Silka Silkaflex EBT from screwfix.
The reason I am taking down the inside first before going up and sealing the outside is because I'm not sure of how they construct motorhome ceiling for structural support if its timber then they could all be rotted, if its aluminium or steel they could be corroded.

I would appreciate any help and guidance on this matter.
Many thanks
Paul

Flicka · Apr 3, 2015

Hi Paul, how extensive is the damp? If most of the ceiling appears damp, I suspect that the timber framework will have started to rot & could have caused corrosion of the Aluminium outer skin. Worst case will be that the rot has also started on the wall timbers. then it will be a major job beyond the scope of most individuals. So hopefully not extended that far.
For ceiling panels try Magnum Motorhomes, Grimsby or O'Leary's, Beverley they both usually have stock even if it's not shown on their websites, Other possibilities are Charles & Son's, Poole or Autovan, Wimborne or Autocraft, Stavely.

PaulandOla · Apr 4, 2015

Hi thank you for your reply
Quite extensive, half of the ceiling timber supports were so soaking wet and rotted they just disintegrated on removal of the ceiling panel which pretty much just fell down on its own with a little help. So of the edge timber supports have rotted. I have started removing as much of the rotted timber as I can with compromising the structure of the van, the rest I will remove once I start to rebuild the first half. I have removed the rotted timber plus cut past where it starts to be dry about another 100-150 mm to make sure the wood rot doesn't spread, I have also treated the remaining wood with cuprinol deep penetrating clear wood preservative. (which now I am not so sure I should have done reading an article on Aluminium)
There are corroded pin hole size holes in the roof, and on the side outer skin in the bathroom, as well as one large hole about the size of a fist. I have posted this thread on Out & About Live forum with pictures here is the link: http://www.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Coachbuilt-Motorhome-Costruction/37800/
(not sure how to attach photo's on here) but got loads of really over thought and negative replies, about my only option is to re skin the top and the side, another bloke said better to just scrap it and count my losses. I am a competent DIYer as well as a qualified carpenter. So not phased by any of this, and I'm a big believer that everything can be repaired within reason obviously.
My plan of action was this:
>My first step was obviously to rip all the rotted smelly damp timber out, so the motorhome can start to dry out, and I could see how extensive the damage was and where the leaks seem to be coming from. I have put a tarpaulin sheet over the roof whilst carrying out the work as I have no choice but to do it outside.
>Now with 90% of the rotted timbers removed along with fittings, lights, mirrors, wall panels etc. I have treated the corroded Aluminium with Kurust (again not sure I've done the right thing here) I wanted to use a proper Aluminium corrosion cleaner/remover but had no joy in finding one. I then want to run down the inside of the wall skin where the larger hole is and the larger hole on the ceiling with a 400 grit paper before either bonding a new piece of aluminium over the hole from the inside and outside on the roof, then coating with a rubberized Motorhome roof leaking paint which as very good reviews. On the side skin slightly different approach was going to rub down the out side once the new Ally as been bonded to the inside and apply a fiberglass resin sheet, then later sand down and paint to match existing bodywork colour. The smaller pin sized holes I was going to apply to think coats of this paint to the outside of the roof, maybe the inside as well. My main concern is stopping the corrosion from spreading anymore (killing it) and then protecting the inside of the Aluminium skin with some coating (heard zinc chromate is the best but can't buy it anymore) I've researched and apparently you can use a waterproof wax or clear varnish there are a few products to choose from.
> Then comes to the rebuilding part, I was planning on using either a foil or polystyrene thin sheet as a membrane against the Ally as like you clearly pointed out once the timbers get wet and start to rot they release chemicals which corrode the Aluminium so I want to try and prevent this. Then I will use 3/4 mm exterior ply, followed by the treated timbers to make up the frame work, 25 mm kingspan celotex in fill in between the timbers and finished with either the proper 3 mm ply decorative wall boards from magnum or 3 mm exterior ply again finished with a vinyl wall paper finish, done to a very high standard so the paper looks good and not just thrown up.
> I'm using stainless steel screws and angle brackets to attach the timbers to the solid edge/wall timbers.
> Finally I want to upgrade the out dated old and tatty surface mounted ceiling lights with chrome or brshed steel finished flush fitting ceiling downlighters probably 4 and operated by a single switch for on/off operation, and a new larger more modern roof light, sandwich type design as at the moment I am left with about 20 screws poking through into nothing where they were screwed to the timber roof light frame, now rooted and gone. Holes in a motorhome roof is always bad and will inevitably lead to leaks. I plan to once the larger 500 x 500 mm frame as been constructed to cut out all these screws and holes and fit in the new roof light.

TonyJones · Apr 4, 2015

You've got a real project on your hands Paul (or Ola?).
It would be good for everyone to see some before/during/ after photos- then people can offer advice as you go along. Lizzie tells me this can be done, but they need to be uploaded to a photo site (eg Flickr) first.
Without wanting to "knock the competition," all that negativity and sniping was the reason I left OAL.

DonnaG · Apr 4, 2015

We've had the same problem although to a much lesser degree, by the sounds of it (see Practical Motorhome Feb 15 issue). Our roof timbers seem to be solid although we can see a small amount of distortion in the ceiling panels. At the moment we're working on the theory that while the roof stays where it should be, we won't start prodding, but I'll be really interested to read about how you get on with the replacement from inside; it's a possibility we've raised for the future so it's great to hear someone else thinks it's possible and is indeed, in the process of doing it.
With reference to the pinholes in the aluminium roof, we used a company called Polytec Coatings, in Wrexham http://www.polyteccoatings.co.uk/ and had a polyurea coating hot-sprayed on the roof, which covers pinholes and stops any future leaks.

PaulandOla · Apr 4, 2015

Thank you for all your comments

I know I have one hell of a project on my hands and intend to document and take photographs throughout. I am quietly confident I have the knowledge, the skills and above all the patience to take on such a challenge. I am some what of a perfectionist and if the van was a newer one, worth more money, or I bought it from new that without doubt I would have it done professionally in a workshop or at least put it in a workshop or barn and then dismantle it, take the roof off back end apart and rebuild as it would have been done from new or (better) as we are now in 2015 not 1997 ;-)

But means must, budget, already started the project outside and frightened to move it now. I will prevail, I am determined to do a top notch job, and the work I will carry out will be up to a very high standard. I wish there were somewhere local to me within 40 miles or so to be able to go and buy the sheets of vinyl paper covered caravan wall boards. Magnum do stock them charge £19.20 p&p and then say that they arrive damaged on all edges by TNT courier and can't be helped.

Regards
Paul

Flicka · Apr 4, 2015

Having seen the photo's on Outandaboutlive, you have a major project Paul. If you post your location (or add it to your profile) maybe alternative suppliers nearer to you can be suggested. As it is parked outside & you don't wish to move it's current state, would it be feasible to erect a temporary (scaffold) tent over it to eliminate any further water damage during your repair process ?
I think the suggestion on the "alternative" forum regarding resheeting the rear aluminium wall would be the "best" solution.

bonfireboy · Apr 26, 2015

I had damp problem with the roof, support timbers rotted, pinholes in the aluminium.
Replacement aluminium from Magnum in Grimsby - if you collect make sure you take a big vehicle / trailer as the roll of metal is big. I stripped out all the cross member timbers, the actual roof lining was mainly OK so I managed to retain that, as were the sides. The insulation is polystyrene so it dried our fairly fast.
Once it was all back together I have repainted the whole roof with Rust-Oleum Noxyde from Rawlins Paints - a year on it seems to have provided a good seal.
Good Luck

516yuanyuan · May 16, 2016

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