Composite motorhome build, Advice needed on sandwich panels

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Composite motorhome build, Advice needed on sandwich panels

Post by Eiemana »

Hi, I'm going to be undertaking a project very soon, I have an LDV convoy van, a cab and chassis van. I am going to build my own coachbuilt motorhome on the chassis, however i used to own an aluminium cladded motorhome and have decided against these construction methods due to damp problems and also repairing damaged panels. I am going to use sandwich panels, foam core with fiberglass skin either side, vacuum bagged to keep the weight down. However, I'm not sure what foam to use, and what weight and weave of cloth to use. I had in mind polystyrene foam, as in the uk i can buy it very cheap from most bulding supplies in 8'x4' sheets, and i would have to glass it with epoxy. I would like to do it in 25mm thick foam, guessing the only reason the older motorhomes had 50mm thick walls was to allow for the timber framework. i'm sure with composite construction i will be using that i wouldnt need such framework, the fiberglass and foam all taped on the joins etc would be rigid enough.. so am i ok to think this would work ok? please tell me if its not as i do not want to get halfway through my build or worse my holiday and suddenly realise its wrong!! so main question, would eps foam and epoxy with no extra framework be sufficient, and second, what lay up would i need to use?? thanks if anyone can help!!!

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Joined: Mon Apr 29, 2019 9:58 am

Re: Composite motorhome build, Advice needed on sandwich panels

Post by Sco »

Hi Eiemana, I haven't used any forum before so not sure if this will work.
I have had some experience with some foam sheets but not with fiberglass cladding it.
Polystyrene will turn to a gooy mess if contacted by petrochemicals.
I am nearing the completion of a motorhome conversion of a 1988 High Deck Danning Landseer.
I re clad it with aluminium composite panel from Fairview. It is fire safety rated. It consists of a sandwich of an inner and outer layer of aluminum with a fire resistant core, It is painted with a very durable coat.
Another foam, with possibly the highest thermal resistance available would be polyurethane.
It is formed in large blocks and then cut to the desirable thickness. I purchased 40 mm and 50 mm sheets for insulation for the Denning. I can't comment on the strength of the construction you have chose as I not closely examined the materials used in commercially built motorhomes.
I trust this may be helpful.

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