Kingspan insulation?

[Da dan]

Thinking of using 25-50mm? kingspan as insulation but don't want to create a problem with condensation and thus rotting. Used sheep wool before but on inspection it just held the water so took it out before problems occurred. Just want to hear what the kids are saying so we don't have to shout (so loud). Any thoughts/help welcome. Many thanks


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[clift_d]

It depends on the kind of insulation you're talking about. Kingspan cavity insulation (K8, K15,etc) is open cell which means it allows water vapour into the pores of the insulation. Kingspan Styrozone, or similar below ground insulations, are closed cell insulations. They don't allow the water vapour in but also don't perform thermally as well as the open cell stuff unfortunately.

If it was me I would use Styrozone bonded to the skin of the van and then apply a layer of polythene or similar on the inner face with properly taped joints and edges, to stop moisture vapour getting in behind the insulation where it can condense.

[Da dan]

Silicon it on? How thick? Regarding the vapour barrier do you think a roll of dpm would work ok? All taped etc? All help appreciated. Thanks


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[clift_d]

A DPM product should be fine. In terms of adhesive maybe look for a spray contact cement that's compatible with the insulation. In terms of insulation thickness, whatever it seems like you can reasonably fit in.

You can also use alternative closed cell insulations other than Styrozone- some people on the forum have used pipe insulation sections with some success. The key is making sure it's closed cell so it can't take in and hold water, and putting a VCL (vapour control layer) on the warm inner face to stop warm moisture vapour from inside the van getting behind the insulation to condense on the cold steel skin of the van.

[Da dan]

Yes I remember now seeing on here a guy using pipe insulation. Also allowed air flow. Good stuff. Think that's the way I will go. Prob won't need to slick either?Thanks


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[clift_d]

I really don't think you'll get much airflow behind, certainly not enough to prevent condensation. The only certain way of avoiding moisture condensing behind your insulation is to prevent it getting there in the first place with some type of vapour control layer.