RV Insulation R-Values – a Dirty Little Secret

Confession: I kinda have a thing for insulation. R-values excite me.

It comes with the brain type, I suppose. I’m an RV engineer by day, intrepid blogger by night. And I DESPISE – that’s all caps – many of the myths, misconceptions, and outright lies surrounding common types of RV insulation.

By the way, I wrote a condensed article on this topic that first appeared on Ashley Mann’s RV Inspiration. I encourage you to go check it out, especially if you’re considering renovating your RV (and to read more of Ashley’s excellent DIY RV content!)

One response to “RV Insulation R-Values – a Dirty Little Secret”

  1. tirod3

    Thermal bridging has become a conversation online with DIY RV makers. Seems a lot of attention is being placed on it, and what we really lack is some hard numbers. Hence, why I think it’s said it’s from 10% to 50% of the heat loss.

    Considering all the other ways the article discusses, it’s likely much closer to 10%. And, it’s also one of those things we have to simply put up with, same as in our homes, because of the expense in producing structural support that has thermal breaks. I used to bid commercial doors and frames – the back door of the Mall – and thermal break frames, while effective, were simply ignored in plans below a certain latitude. Their effectiveness didn’t pay back enough, soon enough, to bother. Not that I don’t understand, having replaced aluminum framed patio doors that use to sweat and freeze shut during the winter. I fixed that issue with vinyl framed doors of much more modern spec, and overall, improvements like that around the house have kept my electric bill flat over the last 25 years – even reduced it.

    With an RV, we live with the compromises which are part of the tradeoffs. I’ve considered building a small squaredrop, the cost of 2″ of closed cell foam is about $1000 for 400 square feet of coverage. Poly iso is slightly cheaper – but on a cash flow basis, neither is affordable. However, a diesel heater is, and that is how a lot of us calculate our purchase. For the few times I might need it, it’s cheaper to run the heater than spend the up front cost that I will rarely need. In terms of technical integrity of construction I want the foam, reality and dollar budgeting simply conspire against it.

    However, in larger scale production, we should now ask those who make cold weather RV’s when they plan to move to that. Mass production offers cost reductions and the use of closed cell spray has major advantages in complete fill, sealing, etc. Even at the 1″ level for three season comfort, the process seems superior, and can be that intermediate step between stick and tin vs composite panels. Its basically making composites in situ, then closing up the interior (or exterior.) No press or machinery needed, bonded thru and thru.

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