Insulation - Earthwool?
- Thread starter ktg1000
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Problem with any wool or fibreglass type insulation compared with foam is that it settles with vibration and Road shock leaving a void at the top. It needs to be supported.
Personally I’d use the multilayer foil type insulation.
I also investigated insulation options and got scared off from talk of condensation rusting out my van. I've just finished (mostly) recladding my house. Gone are the days of sarking, it's now all about vapour permeable membrane. I used a fibre cement version but you can get rolls of flexible membrane very cheap. This prevents movement of air but allows movement of water one way only. I'm now reconsidering my options. Hard to see how glasswool with a membrane would not be the best choice. These things spend months compressed in bags and spring back to their specified thickness, it's hard to see how some vibration would leave a gap if it's squished in a bit in the first place.
You need to remember this is not a house we are talking about it's a metal box on wheels where vibrations cause untold issues, this is why the auto industry use stranded cables as the vibrations make solid core cables go brittle. Glass insulation doesn't suffer from vibrations in your home so doesn't settle in the way it will in the van.
Also the timber in your home needs to breath hence breathable membranes. Steel does not breath and will only trap moisture and slowly rust away.
Don't make the mistake of thinking you can use standard building materials in your van, the materials available for vans aren't different just so companies can make more money.
Earthwool is coated with a treatment to help it stick together and retain its loft. The useless stuff they put in my roof was not that and broke down in 2 years.
Steel doesn't breathe, thats very true, but the membrane would be on the inside rather than outside of the insulation and facing in rather than out, so if it's relatively well sealed, the only place for any moisture to go is into your cabin, and it will certainly be encouraged to do so when it gets hot.
Sometimes the materials for different sectors are different because "that's how we do it". There were good reasons not to use glasswool and sarking when the glass settled and the sarking wasn't a 1 way vapour membrane. I expect this is the reason for the oft repeated advice not to use house insulation, and I suspect think it's not valid anymore. For shits and giggles (and a touch of science), I'll do a section of my van with earthwool and membrane and seal a humidity sensor in with it and even damp the glass down with a bit of water to get the party started. It's summer here in aus so I expect I'll see the humidity start off very high, and drop fairly rapidly as it gets hot and exits into the cabin.
The car builders kit in Australia advises sealing the cavities. If moisture gets in, it's not coming back out. That sounds worse to me than using glasswool and a membrane.
I suppose if you suspect previous advice is not relevant anymore then yours is the advice we should all be following now.
Of course a short term experiment might show some good results but who knows in the long term what may happen, but let's not go with the experts let's just make it all up.
Of course a short term experiment might show some good results but who knows in the long term what may happen, but let's not go with the experts let's just make it all up.
Re-inventing the wheel? It is obvious that a square wheel is far better. 
I'm not saying we should follow my advice, but I'm prepared to give it a go and report back. If the results are good, I'll do the rest of my van, also with sensors, and you can get some long term results too. With sensors to monitor for moisture I'm confident my van is safe, and it might provide a better outcome for everyone.
Experts without a reason to find better ways of doing things won't find better ways of doing things
If your away to spend thousands on a conversion why try a save a few quid by using rockwool ?
Then have the worry of it not doing the job and having the hassle of monitoring it.
What if you find after a couple of years that’s it’s actually a crap idea and you have to rip out your conversion and fit the correct stuff that’s designed for the job.
All to use some spare rockwool ?
Certainly wouldn’t be me.
Then have the worry of it not doing the job and having the hassle of monitoring it.
What if you find after a couple of years that’s it’s actually a crap idea and you have to rip out your conversion and fit the correct stuff that’s designed for the job.
All to use some spare rockwool ?
Certainly wouldn’t be me.
I not sure that any of these membranes (breathable or vapour control) are one way (in the UK at least). Breathable membranes stop water due to the size of the droplets but let vapour through, but do this in both directions (just like Goretex). The ‘smart’ vapour control layers (such as Tyvek Airguard Smart) change the amount of vapour that comes through as the gaps in the membrane change size depending on heat/humidity. Useful as it allows water vapour to escape in the dry summer months but acts as an VCL in winter. Again these work in both directions. All the ones I’ve seen that say to mount in a specific direction are so that the writing is visible for advertising and so the building inspector can see it but not for performance reasons. As the attached picture Tyvek (for example) says it can be mounted either way.
In a van I’d use either a polythene VCL to completely stop vapour getting to the insulation or a smart VCL to allow any vapour that does get through to escape back into the van when the conditions are right.
Because I have ADHD and like projects
I don't have much leftover wool, I'll be buying more for this, and I don't have any membrane so will need to buy that too.
I've already got a smart home setup so monitoring the sensors is no big deal, I can even have them alert me if the humidity sensors go above a given threshold.
Also installing the stick on stuff is a giant PITA and not especially effective. My experiment may just be a way to give back to the users here that have helped me in the past.
Here's the membrane I'm getting. Allows "large amounts of moisture to escape" but doesn't allow it back in.
Thanks Ginkster, just checked and you are correct about the one I was going to use, it'll allow vapour in as well as out. There are ones that allow more vapour to pass one way than the other, effectively making them a 1 way valve up to a given difference in vapour either side of the membrane. I'll chat to the builder that told me about it and find out which one he was talking about.
I should also mention that my "conversion" has very little that's not very easily removable. I use my van for so many things that having stuff permanently installed just doesn't work for me.
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