Motorhome Construction materials?

[ken nugent]

Hi can anyone help with the following

 

I have a 2003 Challenger 100 which is the same as Chausson Welcome - low profile. The front part of the roof i.e. the cab over part is constructed in a one piece fiberglass unit it then joins to what appears to be a fibre skin which is the main part of the flat roof, right to the rear and down about 6" onto the back panel, this part of the roof seems to be quite wrapped and if you press on it there is an obviously gap in places between what appears to be a very solid base, is this normal or is it a consequence of the sun unbonding it. All the joints appear to be in good condition but for good measure I have sealed around all the edges, roof lights, vents etc. Also do you know what the basic frame is made out of is it wood, alluminium or steal ? or dont they have then in our days.

 

Thanks ken

[Guest JudgeMental]

All I can share is how mine is constructed. The GRP roof floats, this can be a bit alarming until you realise it is built like this for a reason. the skin would crack if bonded to sandwich like the walls, because of the changing temperature......

[crinklystarfish]

It sounds to me like it's delaminated, ie the bond between the GRP skin and the insulation, or insulation and roof lining has come apart. I would absolutely stand corrected but as far as I'm aware there is no manufacturer that 'floats' an outer skin over sandwich laminates. Repair is pretty involved but kits can be bought. If it's only 'floating' in a few minor spots, I'd personally leave it and see if the problem develops before going to the rather drastic remedial work needed.

If they are built this way, I've learned something today.

[Guest JudgeMental]

Wrong....don't worry it is perfectly OK

[crinklystarfish]

I doff my cap.

[Robinhood]

Sounds perfectly normal to me. My Rapido has similar construction, and the outer GRP skin isn't attached to the underlying (solid) roof structure, but simply 'laid on'. Under different temperature gradients, the GRP will 'warp' slightly in places, leaving a gap between it and the underlying structure.

 

Been like that from new, and I suspect, as has been said, it's built like that to resist thermal stress.

 

Totally different issue if you get similar symptoms in a sandwich structure wall or floor!

[crinklystarfish]

Out of curiosity, with this 'floating' style of construction, are these roofs able to be walked on?

I imagine that if the outer skin (grp or otherwise) isn't part of the laminate, and the laminate is composed of just a layer of insulation and the inner ply, then that's going to be one weak structure and would be heavily stressed (read bend) if asked to support the weight of your average motorhomer.

Or is it that the outer skin is laid on top of a conventional 3 part sandwich - but then if it is, why bother with an unlaminated outer outer skin?

Also, where the roof is penetrated by vents etc, if there is different thermal movement going on then the sealing around any aperture is surely going to be compromised?

It must make work on the production line more involved too, having to faff about 'skinning' when other manufacturers are just working with one sandwich panel.

I'm not convinced about the thermal movement justification as surely, if that were necessary, all 'vans would be built that way, and presumably thermal stresses on the sidewalls would also prevent a full three part laminate construction of those too?

Not trying to be contradictory here, just wanting to understand.

Genuinely don't get it.

[ips]

I concurr with other posts, its pefectly normal dont worry about it.

[Guest JudgeMental]

Crinkly you kinda answered your own questions earlier...why do a lot of vans suffer from GRP crazing and delamaniating - because they are poorly built, with no regard for expansion.

 

you can stand on my roof it only lifts slightly in high summer

 

watched the excellent documentary re Concorde last night, and that stretches 8 inches at speed. the pilots on last flight jammed their hats in the gap, and they are now there for ever....

[Mickydripin]

Dont know where you get all this info about floating roofs as I was going to accept a new CI Carioca 746 in exchange for my van and there was more waves in the roof panel than on the sea front.

A dealer near to me told me of this problem and that he had returned a Ci to Autotrail as it had this problem he said that Autotrail had offered him a discount if he accepted the problem, being one of the decent dealers he told them to fix it. He was also told that there was going to be redundancies at the CI factory at that time and the builders sent out a few of these problem vans.

In my mind if the roof had delaminated then it would move and what would happen to the sealent on the joints after a while surley they would start to leak if the sealent they use starts to harden then crack.

if you have one of the CI circa 2008/2010 have a look at the roof on your van

[crinklystarfish]

I've been genuinely intrigued by this one as I just can't see the logic of a 'floater' from an engineering perspective. I do however perceive the downsides as outlined in my last.

I've had a bit of a read around and can find no mention of a non-bonded skin apart from in some very cheap American coversions that are well known for their leaks.

I have a couple of reputable books about building motorhomes and have had a look at some of the major manufacturers' websites, including one that will sell grp skinned laminate paneling by the square metre, and nowhere can I find reference to anything other than a 3 part fully bonded laminate comprising outer skin, insulation, and inner skin.

I'm not convinced the phenomenon is 'normal' in spite of it seemingly being reasonably common.

I hope that there is someone out there who has industry knowledge of this and can shed some light for us.

Again, not wanting to be alarmist or disrespectful to anyone's explanation, but such a 'van will never find a home on the Starfish's driveway.

As an intentional construction 'method', it seems bonkers to me.

[Guest JudgeMental]

Why you have difficulty understanding that roofs stretch and retract with heat and if not designed to float can crack is beyond me.......

 

Do you think a company like Euramobil and other quality European manufacturers would by your admission do this more difficult installation if it was unnecessary.

 

Vents, windows and Hekis are sealed using a type of sealant that stretches? and I am assuming in the small area around these that the roof sheet is bonded, I cant be bothered getting up to look or to find out from manufacturer because i am not the one with the lack of understanding.....

 

I buy German because they know how to build campers. For years I have read about other vans delamination and crazing...it is unlikely to happen to mine.

 

 

[art338]

Crinkly,

 

If you are in anyway engineering minded you should be well aware of the expansion of materials, be they metal or plastic.

 

Nailing everything down tight is a recipe for disaster.

 

art

[Mickydripin]

art338 - 2010-07-13 8:32 PM

 

Crinkly,

 

If you are in anyway engineering minded you should be well aware of the expansion of materials, be they metal or plastic.

 

Nailing everything down tight is a recipe for disaster.

 

art

 

Am I a figment of my imagination or do members only answer to members that have been on this site for a while and think that they are the only ones that have an opinion or know anything

I have stated a fact from a dealer you know the people that sell the vehicles that dont admit to anything normaly whatever you think if the roof is loose and wobbling all the time when you are driving around that can not be good all these vans that we pay a lot of money for are panels screws and sealent and by my way of thinking should be flexable yes! but not flapping in the wind the sides and back get the sun on them as well maybe not as much but you do not see bl---y great air bubbles or delamination as you call it all over them or we would soon be after the dealers to complain they should be lamanated down and until we get someone from the manufactures to tell us differant I want a roof that does not have air bubbles all over it :D :D :D

[Guest JudgeMental]

Mickydripin - 2010-07-13 9:34 PM

 

I have stated a fact from a dealer you know the people that sell the vehicles that dont admit to anything normaly

 

 

A fact is it. Was this the same dealer that sold you the van that you could not use for 2 years I wonder.......It seems like you never learn, what do most dealers know about motorhome construction, most are just salesman, could be selling you anything.

 

Your contributions on this subject would be laughable if not so downright stupid

[BGD]

"I have stated a fact from a dealer........."

 

With all due respect, it seems to me that you have simply repeated here what you recall a salesman (woman?) telling you.

 

That the person said such a thing to you may well be factual.

But that does NOT correlate with what they said being an engineering or manufacturing fact.

 

Dealer salespeople (almost) without exception know utterly diddly-squat about how the products they are trying to sell are designed or manufactured; nor about the engineering or physical properties of the components.

They may know something of sales techniques, a little about how their payment-by-instalments at big interest and commission-for-them deal works.

Salespeople will tell you what they think you want to hear. And if they don't know, they'll generally bulls**t to appear knowledgeable.

 

Soz.....

 

 

[Mickydripin]

JudgeMental - 2010-07-13 10:38 PM

 

Mickydripin - 2010-07-13 9:34 PM

 

I have stated a fact from a dealer you know the people that sell the vehicles that dont admit to anything normaly

 

 

A fact is it. Was this the same dealer that sold you the van that you could not use for 2 years I wonder.......It seems like you never learn, what do most dealers know about motorhome construction, most are just salesman, could be selling you anything.

 

Your contributions on this subject would be laughable if not so downright stupid

Thanks Judgmental it is sarcastic remarks from morons like you that stop people from posting in case they dont put things just how you want them to

And no it was not the dealer that sold me the van that I could not use but another dealer that was trying to help me not like you I am lerning but not from people like you some of the posts that you put out are not helpfull but people dont come back to you with nasty remarks it seams like your trade mark to put people down

[art338]

Mickey,

 

If you disagree with what is said by others then do your own research and tell us all what you find, we would love to know all the inns and outs of bodywork assembly and you seem to be the ideal person to enlighten us all.

 

Regarding do members only answer to members etc; most certainly not but if a question is asked you can be sure that there will be some straight answers from very knowledgeable Motorhome users, auto mechanics, precision engineers and end users of plastics.

 

PS. And we are not morons who make sarcastic remarks, we answer questions and aim to advise others who may be not so enlightened Motorhome users and who may have been misled by sales people.

 

art

 

[Guest JudgeMental]

Mickydripin - 2010-07-13 10:58 PM

 

JudgeMental - 2010-07-13 10:38 PM

 

Mickydripin - 2010-07-13 9:34 PM

 

I have stated a fact from a dealer you know the people that sell the vehicles that dont admit to anything normaly

 

 

A fact is it. Was this the same dealer that sold you the van that you could not use for 2 years I wonder.......It seems like you never learn, what do most dealers know about motorhome construction, most are just salesman, could be selling you anything.

 

Your contributions on this subject would be laughable if not so downright stupid

Thanks Judgmental it is sarcastic remarks from morons like you that stop people from posting in case they dont put things just how you want them to

And no it was not the dealer that sold me the van that I could not use but another dealer that was trying to help me not like you I am lerning but not from people like you some of the posts that you put out are not helpfull but people dont come back to you with nasty remarks it seams like your trade mark to put people down

 

Now that is funny you utterly insulting and stupid man. I and others, unlike you with your scare mongering, tried to put the OP's concerns to rest. whereas you are to thick to listen to reason, or do your own homework. I suggest you engage what brain you have before posting......

[crinklystarfish]

I’m very well aware of the expansion and contraction quality of different materials and use it to my advantage to assist in constructing press-fit joints in some of the metal-work projects I’ve taken on. 

Indeed it’s the fact that materials do expand and contract at different rates that will ensure any free floating skin, not laminated to the underlying insulation, will warp, buckle and generally slide around over the insulation, and thereby exert extra pressure on the sealing compounds used around roof lights, vents, and wherever else the ‘floating’ panel is ultimately securely fixed to the ‘van. 

By having all three skins laminated, the whole sandwich panel will grow and shrink very marginally but because only two surfaces instead of three are exerting a sheering force there is far less likelihood of compromising the (flexible) sealant used at critical joints. 

So thanks, yes, I do fully understand that it is unwise to fail to allow for some thermal movement, as it is to fail to allow for some physical movement generated by forces whilst travelling. I also fully understand that introducing an extra sheering force into this equation is equally unwise. As my post above, if the justification for ‘floaters’ were thermal stress, then it seems logical that all ‘vans would be built that way, as would all sidewall on all ‘vans. 

I can be bothered to look in books and have owned several German vans, none of which has ever had a floating outer skin roof. 

If owners think that ‘floaters’ are OK, that’s fine by me, I don’t mean to provoke angry defence, I’m just genuinely interested in how ‘vans are put together.  

It strikes me that no one who has posted has any real expertise, and I include myself in that. Unless and until someone who actually knows what they’re on about offers a logical explanation, then it’s highlighted, for me, one more critical thing to pay close attention to before handing over a huge wedge. Makes and models of other 'flappers' would be useful to know if anyone else cares to post.

Re the dealer ‘expertise’ - cutting to the chase, I’d be surprised if Autotrail had offered a discount had there not been a genuine issue. Assuming all involved had been telling the truth of course.

[Guest JudgeMental]

what do autotrail know of Italian CI construction probably as much as me......nothing?

 

I cant comment on other vans or how they are built. what flaps around exactly? Roofs are subject to far more heat then walls. the other vans you have seen/owned were they GRP? are you sure they were not aluminium?

 

Euramobil are in the top 10 of German manufacturers and I trust they know what they are doing, and anything they do I would think is born of experience and best practise.

 

We now know from this thread that at least, Euramobil, Rapido, Chausson and Challenger are built this way.

[Guest JudgeMental]

Now I know this will probably not help some of you, but this is te reply I have just had from Euramobil on the topic:

 

"Yes it is absolutely right that the roof is only fixed on the borders and the center roof is floating, we built our vehicles like that for many years and there is nothing to worry about.

 

Also other manufacturer built there roofs like that which gives important advantages concerning the extension of the glass fibre material. The glass fibre works with the different temperatures (you might have seen that your roof might have lifted up on some occasions) and in case it would be fixed with the sandwich roof those extensions would also affect the other material which it doesn’t do whilst it is loose.

 

Yours faithfully

 

Customer Service-Guarantees"

 

[ips]

Seems fairly definitive to me, many thanks.

[crinklystarfish]

Now that’s useful feedback. Good bit of research. The ‘vans I’ve owned have always been grp until my current one which is aluminium.

I understand the separate inner skin / framework / insulation / outer skin technique that they employ and imagine that it could well be a much cheaper solution for manufacturers than moulding anything other than flat laminates. If bonded to a framework then the ‘sheering forces’ issue is resolved. To be honest I thought that technique had been superseded a long time ago.

I’d still have reservations about the walk-on strength compared to a full sandwich laminate and am genuinely pleased this subject came up. All good learning experience and as before, it’s one more thing to check for when buying for those, like me, who might prefer higher-end construction techniques.

Not intended to be provocative, and once again nice one to Judgemental/>/> for getting the inside skinny.

[ken nugent]

Just to add to the above subjet the roof skin is wrapped but could not be described as flapping around and at the most when pressing it down it only moves 1/4" inch all the joints around it are in sound condition but I have gone over them to make sure and because of its age. I have read with interest and appreciate all the replies to this subject and was about to say it may clarify things once and for all if we had a reply from a manufacturer but the ever efficient and helpful judgemental beat me to it, I feel alot happier now that the roof is not going to blow off.

 

But one thing everyone seemed to have missed was the latter part of my query, that being does my MH have a skeleton frame of wood, alluminium or steel or is it just made up of laminated panels.

 

All replies greatfully received, as usual they make very colourful reading but please guys no bitching or slagging each other off, its all good faith.

 

Many thanks

 

ken Nugent.