Caravan insulation

[mibosa]

Hello forum members,

I have recently removed the ceiling from my 1966 Viscount Ambassador (aluminium frame) and before installing the new one I am seeking advice on what type of insulation to use.  The gap between the outer skin and what will be the new ceiling is about 38mm.  The previous white sheets of foam were in average condition in places but I thought more recent technology would enable something better.  It appears that the higher 'R' rated insulation batts of 175 (+) mm in thickness shouldn't be compressed as this will affect their performance.  And would sarking, as available in Bunnings etc, be useful with a lesser R rated insulation batt?

Can anyone please provide advice on what to use?  
Regards, Mibosa

[Franklin1]

G'day Mibosa,

There are a number of options when it comes to insulation. The hard part about buying insulation for a caravan is trying to get only small amounts rather than having to buy bulk lots of it, and ending up with heaps more than you need.

However, let's look at the options...

 Fibreglass batts: There's nothing stopping you from peeling a 100mm-thick batt into 2 x 50mm-thick batts. Sure, you end up with a lesser R-value, but it'll still keep you as warm as partly-toasted toast.
Click on this link to see how mike0z22 did it in his Valiant van.


Fibreglass blanket: 50mm thick blanket with aluminium foil bonded to one surface. Used under metal roofing. Can be compressed to 38mm. Click on this link to see how I compressed it down to 30mm in an ice chest cabinet.


Foilboard Insulation Panel: A rigid polystyrene core, with aluminium foil bonded to both surfaces. See the foilboard website if you want more details. Click on this link to take you over to the Classic Caravans forum, where you'll see it being used to insulate a 1974 Viscount caravan.


Air-Cell Insulbreak: Only 6mm thick. Made from a closed-cell foam product, with foil bonded on one surface. Used in metal sheds. Downside is that it's hellishly expensive, and you have to buy a roll (which will do about 3 caravan roofs). Click on this link to see how I used some leftover air-cell to insulate a 1977 Millard poptop I restored.

Similar to Air-Cell is E-Therm Thermal Insulation (see website ). Same sort of product, and same sort of problem in the minimum amount you can buy. I bought a roll of this from an ebay seller recently for $150 (heaps cheaper than retail), and will test this out in the ceiling of the van I'm working on. Ask me in a few years what I think of it.


Polystyrene sheets: Same as what you've got. Different thicknesses available. Cheap on ebay if you can go pick them up.


And you though it was all so simple, huh??

cheers,
Al.

[claireandruth]

hi Al and Mibosa - I am thinking of using ether and wondered if there would be people in the NSW or ACT area interested in sharing a roll? 22M is the roll length for the 5mm stuff, although I've emailed etherm to see what they recommend and also if there are seconds or offcuts I can get. I'll keep you posted, but members can PM if they would like to talk about how some rolls could be shared!

[Franklin1]

G'day claireandruth, It's probably not worth sharing a roll, unless you live within a few streets of each other. The costs of dividing it up and getting a courier to deliver the bits would be uneconomical (Aust Post won't deliver it because it's over the 1 metre size at 1350mm roll width).

I've always thought there might be an opportunity to contact the local metal shed supplier, and asking them what the chances are of getting some of the leftover Air-cell//Etherm insulation after the Colorbond sheds have been erected. Surely they must have a few metres left over after every job, and I betcha it just goes to the tip.

One of the main advantages of the Air-cell and Etherm insulations is that they are very flexible, so they go around curves quite easily. The R-value is only around 2.0 but that will stop all ten fingers and toes snapping off in the alpine regions (only 8 fingers and six toes will snap off, heh heh ). Plus, you don't have the "messiness" like you do with fibreglass fibres.

For straight flat sections in a van, the cheapest is the polystyrene foam stuff. Available in fruit boxes from the markets for nix (I think murray used them recently on his Viscount), or from white-goods retailers when they unpack the fridges and washing machines for display in the store. It's just a waste product for them, so they'd be happy for you to take it all away from them.

For the fibreglass batts or blankets...same deal. No builder I know can calculate exactly the right amount of insulation that is needed. The leftover stuff usually gets left in the ceiling cavity of the house. If you know any builders, tell 'em you'll happily take any leftovers off their hands, and it won't cost them a cent!

cheers,
Al.

[claireandruth]

Hi Al - yes, for a sunliner's curves, the flexibility is worth the relatively low insulation (GRIN) - a reduction in snapped off toes is well worth it, as well as hopefully some summer heat too. My van had her gelcoat taken off, so there is not much between me and the elements! thanks so much of this info tho, its really helped 'gel' my thinking!

[mibosa]

Well, after a long day frustrating day at work it is great to come home and read some responses to my question. I thank you all for your responses. I have decided to go with the sheet of sarking and fibreglass insulation which I can get off Gumtree locally at a good price. It means that my roof space will be about R3.5+ eventually which will be okay.
When I removed the old ceiling I disposed all the old foam sheeting, making the most of all the bins in the street and then realised that I may have dumped it too soon. But all is good, I'm still happy with my original plans.

Thanks to all, thanks Al.
Bob

[claireandruth]

good luck!

[Franklin1]

For the sake of adding to the information in this thread...


Thermobreak thermal insulation: various types produced (see website ). Click on this link to see how it was used in atouchofglass's Olympic van (read the linked post and a couple down from that). He'll be able to provide info on how it has performed, and availability of supply; cost; etc. The type 'Atog' used had a peel-and-stick surface on the back, so it could be stuck to the inside walls of the fibreglass.


Insulmist Thermal break insulation: similar to the closed-cell foam type described in the previous post above (see website ). It appears that there are a number of different brands that are based on a similar insulating method - thin sheet of foam with aluminium foil bonded to one surface - eg. Air-cell; E-therm; Insulmist; etc etc.


Silver Foil Bubble Wrap insulation: I notice in a search on ebay that this type of insulation can be bought for about $10 per square metre including postage around Australia. Various sizes/lengths available, including small amounts that would suit a caravan project. I have no idea how good/bad this type of insulation is, so you would need to do your own homework first before deciding whether to use something like this. Click on this link to take you to the seller's store, and all the items listed.


That's enough knowledge now...head starting to hurt...

cheers,
Al.

[onesneverenough]

Hi mibosa

Friends of mine used foil board on their house and are extremely happy with it. My partner recently installed it on our Franklin but it has not progressed much beyond this stage so we don not know how effective it is. I agree that it would be difficult to use Foilboard around complex curves however we were blessed in not having any. The sheets were about $30 each and i think we used about 4 or 5 so far and are yet to install it in the roof.

I had a look at the website and could no find reference to to it but i believe it is the case that it is necessary to have some amount of an air space to work effectively.

[mibosa]

Thanks OnesNeverEnough for your response. I am just in the process of making a new wooden hatch frame then will get to the insulation and new ceiling. Although everything is subject to change, I have decided to go with the ceiling being R2 insulation with the reflective sarking, which should give me about R3.5 in total. Bunnings do rolls of R2 insulation which is 90 mm thick but will compress (not too much)to fit in the 42 mm roof space. I would like to use a higher R rated insulation plus the sarking but internet research I have done suggests that if you compres some of the thicker insulations into small spaces, then it drastically reduces its effectiveness. Still, anything must be better than nothing?? Thanks again.