I would stay away from any product which would emit VOC like tar.
In my opinion foam sheets are great for insulation but van's nooks and crannies are difficult.
Best for 4 seasons would be a C -RV with flat wall insulation sandwiches done on a factory press.
If you plan to have aluminum framing make sure to use thermal breaks between the chassis and Al framing. In my O/H cabinets I used structural fiberglass angles.
Thinsulate is not something I’m opposed to but I’m missing the advantages of it over polyisocuranate. Seems more expensive and thinner.
At any rate it’s the nooks and crannies and the structural sheet metal ribs/supports that’s the challenge. I understand the buckling issue can be fixed by using foam that expands less? Window sealant I think?
I’m kicking around the idea of making a unified wall structure that doesn’t try to fit the curve if the van wall. Just straight up for so many feet then a fixed angle for so many feet to the ceiling. I can insulate that, and fit it to the sides and leave air gaps in the rib space or just fill those and not worry about the nooks and crannies. Basically a shell wishing the van body, structurally connected to it, thermally isolated. I would lose two inches of width for every inch of insulation, but it could be pretty modular. 80/20 May make this easy to build. Not ideal but it might be worth the tradeoff for build optimization.
The more I think about it the more I’m convinced this needs to be four season capable and I am gonna have to DIY. If I’m going that route I’m going to design for replication. So if the van is totaled I can recreate it very fast, even use the modules in the next van. This may not be practical but looks like it is at this point. Won’t be able to tell until I have the van in hand.
I saw someone using fiberglass angle to isolate internal structural aluminum from the van structure and was stealing that idea, only my thought is to use UHMW. UHMW is polypropylene of high molecular weight, and can be worked like wood, is electrically and thermally jnsulating but not rigid and brittle like fiberglass angle can be. (Tears rather than sheers). It might be a bad idea but I’ve worked with it in very high stress environments before— battlebots— and it can take a beating from an opponents weapon.
By the way, I’m pretty Ute the guy I saw using Fiberglass angle mentioned he got the idea on the sprinter forums from a George, so maybe that was you— it’s a great idea!
I agree best for insulation would be a class C with well made insulation. Good structural integrity could come from vacuum forming or solid fiberglass. If Bigfoot we’re still making motorhome a id be keen on that. I have considered remodeling an older fiberglass RV, but that’s looking like several weeks to get to the point where I can start building. (Eg have to tear out the interior, clean and repair it etc.)
Anyway, having looked at a bunch of RVs, right now when I see a TRAVATO (about $80k Street price) I figure it’s worth the $40k over the cost of a bare pro-master to do it myself.
Though I’m torn. I’d rather buy than build, but I’d rather spend the time doing it right upfront than deal with the consequences of their low quality down the road.
My mistakes will be a lot more fun to deal with than theirs!
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