Java did you put a ply Furr on every rib, or go like 16" centers or whatever the closest rib width worked out to. My thought is that if I did 16 centers I would foam right over those middle ribs and I'd have 3\4" of insulation and might stop the cold coming through. Would also be a lot less grinding. I'm leaning towards the DIY 600 sq foot foam kits.
Thoughts?
I did every rib. I think you could skip every other if your willing to take the time to get the foam perfectly flat. Without that to support the ply/inner skin I think it will be too floppy. I have not been down to super low temps yet, only 28 ish low, and the windows were the biggest loss/conductor, and the cheap *** RV door.
On the DIY foam kits:
I have used them for construction projects in the past. They work ok, if you do a few tricks.
Get an old cooler that the tanks will fit in, fill it with HOT water and dump them in there. You want them at about 80 degrees to work worth a poop. Get extra tips (most kits come with a couple) the will clog each time you stop spraying.
You will not get the claimed board feet out of them.
I would have needed two for my truck by my calculations, at that rate it was only a couple hundred bucks more to have the pros come and do it and do all the grinding too. If you use the closed cell stuff (which you should!) it needed to be ground with a wire cup on a 4" grinder, its too hard for the knives or scarifer style cutters. That was nasty work.