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General: Insulation for camper van

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  1.  
    • CommentAuthorcolonel
    • CommentTimeJul 24th 2007
     
    i am converting a camper van (aluminium box van with hardwood frame) and would appreciate some advice on insulation.
    My goal is to be as green and energy efficient with the conversion.

    I would like to use a green insulation, but at the moment am leaning towards celotex due to its efficiency at small thicknesses.

    Does anyone know if celotex gives off any decompositional gasses over time?

    this is my plan:

    1) floor- 9mm marine ply, 100mm celotex, 30mm air gap?, 18mm marine ply, 14mm engineered wood floor.

    2) walls- 1.2mm aluminium sheet, 40mm celotex, 10mm air gap for cables etc, 9mm marine ply, wall carpet lining.

    3)roof- 1.2mm aluminium sheet, 50mm celotex, 6mm ply.

    any tips or advice especially to do with condensation problems, would it be worth using celotex in combination with a hydroscopic layer added?

    many thanks
    • CommentAuthorchuckey
    • CommentTimeJul 24th 2007
     
    The only point I would raise is that you will get condensation on the inside of the Ali skin unless the celotex is 100% vapour proofed - V. difficult to do. I would put thin vertical spacers between the Ali and the foam with little dribble vents underneath (1/16 " diam holes every 6"?) so any condensate can find its way out. It could get into your flooring system though, so some extra precations would be needed to avoid that.
    Frank
    • CommentAuthorSaint
    • CommentTimeJul 27th 2007
     
    Colonel, I would be very careful with your choice of insulation.
    As you and chuckey both point out condensation is an important issue. Condensation is not the only potential source of moisture of course, water spills in the kitchen area, rain entry through rooflights accidentally left open, spills in the bathroom and all manners of accidental spills (in our case kicking over the dogs' water bowl!) means that the floor is likely to get wet. That means you need a moisture resistant insulation.
    The next thing to consider is loading and dynamics. Especially on the floor you will need a foam with a relatively high compressive strength and bearing in mind the physical shocks (pot holes) and torque imposed on the van in transit a strong shear strength and a more plastic nature is required. PUR/PIR will not give you these properties
    If you look at the build specifications of all the top end camper van builders, whether that be the major builder groups in the North East across to the builders in Worcestershire they all build with extruded polystyrene insulation (XPS) predominantly in the floors. These builders all have access to PURs and PIRs which can be cheaper than XPS but don't use them. XPS copes well with any moisture problems and has a high loadbearing strength. Unfortunately but I guess not surprisingly (even bearing in mind the selling price of these vehicles) most UK manufacturers revert to expanded polystyrene (EPS) the white packaging type or even low density mineral wool in the walls and roof. Cheap and cheerful and the public don't get to see it.......!
    If you go the continent however, especially Germany and Italy where, few people will argue, the best vans are made, extruded polystyrene is used throughout. Most German builders went over to structural sandwich panels for the walls with XPS cores a long time ago.
    As chuckey also says its important to space off cabinets and seating from the walls to allow air movement that then vents away the moist air. My van has a double floor and all air is vented around the back of the cupboard units and seats and then into the ventilated floor space. Personally I would go for an Aerogel fleece in the roof, firstly its flexible and so is easy to install into convoluted roof shapes, it has the best thermal insulation value of any product on the market (excluding active insulation as in vacuum panels) so can be used thinly. It is hygroscopic so will not pick up mositure and also has good acoustic properties.
    • CommentAuthorcolonel
    • CommentTimeJul 30th 2007
     
    thanks for your replies.

    i am surprised that you say that pir will not be strong enough, but then i didnt specify that the floor of my van is built on 5"x2" teak joists strapped to the chassis with 18mm marine ply above..!! (ex fire rescue unit), I was going to seal and fill the spaces inbetween the joists.

    the walls and roof are also constructed of fairly beefy teak frame!

    i will look into the xps and aerogel fleece, but suspect that price may be a factor.

    do you have any thoughts on bonding the PIR to the aluminium skin, and maybe foregoing any air gaps? the sides have an ever so slight curve. i have seen PIR bonded before with expanding foams. I like this idea, but am still concerned about decompositional gasses?
    • CommentAuthorSaint
    • CommentTimeJul 31st 2007
     
    Colonel,

    I still wouldn't go for a PIR. Yes its a good insulation but its a thermoset and has a friable and fairly weak structure. In lab tests where sandwich panels with different insulation cores were subjected to an "IKEA" type repeat stress cycling, the thermoplastic XPS outlasted the PIRs and PURs by a huge margin and sustained far greater loading.
    In the floor where if there's just the smallest chance of moisture getting through to the insulation then no question go for XPS
    • CommentAuthorcolonel
    • CommentTimeAug 5th 2007
     
    ok, so you have swayed me to xps. If you dont mind answering a few mor questions.

    1)do you have any ideas on bonding it?
    2)what brands have you tried/recomend?
    3)what do you think of the idea of adding a foil layer to each side (using material similar to the foil space blankets). it it worth it? talking walls and ceiling more than floor.
    4)how flexible is it? i need to bend to round the slight cure of the vehicle sides..

    cheers

    col
    •  
      CommentAuthorfostertom
    • CommentTimeAug 6th 2007
     
    I won't, I won't say 'what about multifoil' - there - I didn't.
  8.  
    This is just the sort of situation where aerogel insulaton such as 'Spacetherm' should be considered. It has a higher thermal resistance than the PIR and PUR so you get better insulation with less thickness. The downside is cost but in a small structure such as a camper van where space must be critical, that may not be signifcant.
    • CommentAuthorSaint
    • CommentTimeAug 6th 2007
     
    Colonel,
    Firstly with regard to sourcing XPS, I'm assuming you're in the UK? Sheffield Insulations, Trent, Orion or in Scotland, Proctor stock XPS. Grades should be Styrofoam LB or if you can afford the extra, Styrofoam RTM (that's the grade used in the sandwich panel walls, ceilings and roofs of the 40' refrigerated trailers). Not all the Sheffield depots carry these grades. Don't let them try to sway you with the cheaper often lesser strength construction grade XPSs. These are normally suffixed, in the case of Styrofoam, with the word "Mate" or prefixed with the intended application "Floor...", "Wall..." or "Roof...". The construction XPS grades are typically smaller boards and do not have the planed close tolerance face of the LBs and RTMs. The construction grades have far looser thickness tolerances not suitable for good panels. If you have a problem then go to Trent or Orion Insulation, yes they're all part of the big happy SIG family but they carry competitor XPS grades. Try asking for URSA/Glascofoam CT or VIB the direct equivalents of Styrofoam LB and RTM, then mention Jackon/Gefinex, you'll focus their attention and may also get a nudge on the price.

    As for adhesive I'd go for a moisture cured PU but the foam stockists should be able to advise on this also.

    Foil on the face of the insulation that is to be adhered to the inside of the aluminium body might be worth considering but it also make it more difficult to bond to the aluminium.

    For going round slight curves, score the back of the foam every 50mm or so 1/2 to 2/3 through the thickness of the board.

    As Biff says I would like to go for an Aeorgel fleece especially in the roof. The far superior thermal properties, its moisture resistance and the fact that it comes as a fleece might lend itself well to that application. The brand name is actually Space Loft and is marketed in the UK by Proctor 01250 872261. Proctor bonds Space Loft to different substrates under the name Spacetherm. The laminate then could be to gypsum board, Fermacell, ply, chipboard or OSB. Maybe you should consider one of these laminates for the walls. Watch out for the total weight though. In fact Proctor could also supply you with the Styroam LB or RTM plus advice on construction and the adhesive. They will deliver to your door (at a price) Stick with XPS in the floor though if only for the compressive strength and moisture resistance.

    As you will have noticed Biff and I have respectfully not commented on Fostertom's suggestion.........One day Tom.......one day!!
    • CommentAuthorVagabond
    • CommentTimeFeb 27th 2009
     
    Dragging up an old discussion.

    I found this page from a web search and found it most interesting.

    I've got a truck mounted aluminium Luton box w/ fiberglass roof that has had a very heavy duty steel frame made for the base to enable it to be lifted with a forklift from both sides or the rear.

    I modified the steel frame to take some legs to make the box self-demountable from my tipper truck

    I'm in the early stages of converting the box into a camper.

    I'm going to be using the box for extended periods, year round and probably in some rather cold regions. I managed to get some cheap(ish) 6cm and 7cm Celotex that I was planning to use to insulate the box

    The roof is constructed with aluminium cross bearers that have been laminated to the skin. These protrude about 25mm from the roof.

    The walls are made from sheets of alu about 50cm wide folded to slide together with their neighbour forming a 23mm box section in the process. Inside the box extruded alu. rails are riveted horizontally between these 'box' sections .

    I've been cutting 25mm celotex and squeezing it behind the wall rails.

    I need to get the floor in but am now unsure how to progress. Because of the weight of the base I need to save weight at any opportunity.

    The steel base is like a noughts and crosses board with an outer ring. I was going to put 6cm Celotex onto the steel with a 6cm x 1 or 2cm wooden framework constructed with bearers at appropriate points to support internal loading (ie not underneath cupboards etc.). And tape the whole lot to stop water ingress from above or below

    Then use thin ply for the base of cupboards, seats etc. and either 12mm ply or pine floor boards on the actual floor.

    It was all getting a bit complicated and I was worrying about distances between bearers and the need to keep weight down.

    I decided to have a look at a caravan a friend is in the process of destroying to see how its floor was constructed and how solid it felt and was interested to find the floor to be made of large panels which are 6mm ply / foam centre / 6mm ply sandwich which sit on the chassis of the caravan with no other support.

    I thought maybe I could make something similar with my Celotex and negate the need for the bearers so I had a search about on the old internet....

    I doing so I ran into this site and now I'm not sure how to progress.

    I wondered if anyone could offer advice?

    1) Floor. I'm thinking some kind of foam sandwich would suit best, ideally something that would be strong enough to use without requiring more support - the biggest gap between the steel beams of the 0s abd Xs board base is about 100 x 60 cm. I think one piece would be best and with ply on top so I could screw furniture frames down onto it. I'm looking for a reasonable layer of insulation - ideally something at least equalling 6mm Celotex. And weight is a BIG factor.

    From reading the above an XPS sandwich is looking like a good choice - any comments on choice and suppliers? I was going to start looking for companies who might be breaking refrigerated truck trailers and a friend suggested looking for used industrial refrigeration panels (warehouses etc.) although I suspect these would more likely be PIR panels.

    2 - Condensation - presently I've got 25mm Celotex jammed in the walls behind the rails and untaped. I've also got 25mm celotex jammed/taped between the 'beams' over part of the roof. Due to the construction of the box it is a bit hard getting a vapour tight seal, using tape, around the roof edges

    I guess If I tape this 25mm layer, best I can, before screwing pine uprights (which will be in-filled with the thicker celotex or XPS) to the rails I should avoid possible issues with the timber getting wet and rotting) from condensation? The timber will be positioned to provide something solid to screw the furniture to. Final layer would be 3mm ply.

    I could get back my money on what I have by sticking the Celotex on Ebay and spend out on some extruded polystyrene boards as replacements although it does appear lots of people are using celotex in self build campers without any issues.

    Oh yeah funds are a bit tight...

    Cheers

    Darren
    • CommentAuthorSaint
    • CommentTimeFeb 27th 2009
     
    Darren,
    I'd forget Celotex in the floor. Moisture pick up, loading, shear strength, compressive strength all poor but required in this application. Definitely go for XPS, yes its a lesser insulant but it scores well on all those factors above that would damage Celotex in that situation. There are loads of panel makers out there that might knock up a simple 3 element panel with an XPS core for you. Truck panel guys out towards Hull, Panel Systems in Sheffield, AIM in Surrey...where are you?
    • CommentAuthorVagabond
    • CommentTimeFeb 27th 2009
     
    Thanks for that Saint,

    I'm in the south east so AIM are looking good as long as they don't charge Surrey prices (I grew up and ran a business in Surrey, things aren't cheap)
    • CommentAuthorunguided1
    • CommentTimeFeb 27th 2009
     
    back in the early 70s my father bought 1969 split screen VW camper, the intersting thing about it is that the whole of the lower half of the van on the exterior had what can only be described as a type of fur covering (not real fur I hasten to add ) I believe the theory was that when stationary it insulated the van and when in motion it dissipated the heat, the colour was brown. I dont know if this was an experiment from VW or if it was a retro fit at a later date. might be worth some research I also recall it was a very big talking point whenever the van was parked up with people actually stroking the van.
    Regards
    Mike
  14.  
    No, it was just a flocking phase.
    • CommentAuthorSaint
    • CommentTimeFeb 27th 2009
     
    Vagabond,

    Just in case there's also Marco Industries in Sittingbourne and possibly RVL in Uckfield. They both make their own sandwich panels
    • CommentAuthorVagabond
    • CommentTimeFeb 28th 2009
     
    Cheers (you're a) Saint :)

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