Club 80-90 Forums

Hi, i have been wondering about this method for ages, is there any problem with filling the gaps between the inner and outer skin of the van (the bottom of the doors being the main place) with expandable foam? I can see advantages and disadvantages.

Advantages:
- better sound/heat insulation
- no worries about water retention
- lightweight
- quick

disadvantages
- hard to remove once in
- expensive
- possibly block drain holes

The expense wouldn't be a problem for me as i know someone that does this for a job. Apart from the expense though why is this option not much more popular? I dont even think it'd be massively expensive to be honest.

http://www.screwfix.com/prods/29093/Sea ... Held-750ml" onclick="window.open(this.href);return false;

this can would do quite a bit!

No don't do it. Early Mk 1 golfs had it in the bonnet and late Beetles had it above the rear wheel arches both suffered from serious corrosion in those areas due to trapped moisture.

Same as Bigherb, forget any future welding anywhere near the expanded Poly too!

only do it if you intend to make a cross channel boat like hammonds

I agree about not doing it. I did it on van three and it still went rusty from within. I never worked out where the water came from either. Best bet is to use Waxoil and make sure your drain holes/slots are clear. Try to b a bit vigilent in sussing points of entry and check for water/sludge collection areas. a
And yes I know Waxoil can be troublesom when welding but then if applied properly ie from a heated container, it will reduce the need for future welding.
Cheers
Wolfie

I agree about not doing it. I did it on van three and it still went rusty from within.

I thought it was the foam itself that initiated corrosion, but could be wong

Phew! looks like a dodged a bullet there then, if only someone would invent and expandable foam that wasn't porous.

Thanks for that!

Not sure that it is porous, is fine for cavity insulation to join up foam kingspan boards and used it last year in cavities under old rotten box sashes

... but does cause problems I've heard as I say, but then the real problem is access and cleaning up if you do need to do any panelwork, such as welding (noxious fumes maybe?)

Polyeurethane foam has been used for ruggedising such items as defence electronics and by definition presumably does not creat water. Some DIY foams use sprayed on water or moisture from the atmosphere to activate and therefor are unlikely to form an intimate and hermetic seal with the bodywork. I guess if the interior of the bodywork could be suitably primed then it would have a good chance of working. But then if you could prepare the interior of the bodywork you wouldnt need the foam in the first place.
Cheers
Wolfie

Mmmm expanding foam, thanks for that

Makes a good repair though

dont use expanding foam for all the reasons above.

ive been thinking about doing something with the insulation on mine and im looking at using another building product called tri iso. its similar in looks to silver screens, but thicker (and more expensive) but it wont bridge the space between the inner and outer panels. im thinking of a way to attach it to the latice work on the internal chassis. that has better u value than expanding foam or kingspan. dont know about sound insulation though.

tri iso is flammable though, I used on my 81 devon but it got too near to fridge pilot - my fault though - Whole van burnt to a cinder 4 years ago!

dont know about sound insulation though.

Sound insulation covers a wide range of 'noise'... low freq. panel vibration/drumming is the main one we are interested in, together with mid & higher frequency stuff which heat insulation will help with to some extent.. LF panel vibration/drumming requires mass and/or stiffness and as stiffness is basically a function of original design and build, mass and some energy absorrption (hysteresis) medium is required to make a noticeable difference, so those dense self-adhesive bitumen or lead-backed sheets are usually the first choice for any effective improvement.

Personally, I think that those massive bass-units in cars vans should only be allowed if they've sound-insulated vehicle from inside to out , requiring several hundred-weight of panel lining, and they suffer the weight penalty - after all, anyone outside has to suffer sound intrusion into their personal space