Van #2 2021 EXT
I use XPS high load on the floor of my vans without battens. I use XPS high load not for the psi rating but for the water impermeability. Polyiso can absorb liquid water and when it does & when under “load” it can turn to mush.Hey, thanks!
I've used "Jackofoam 300" from Jackon (maybe its a different name over here..), but it looks to be the same product. I've read that XPS performs a lot better than other products like polyiso in cold temperatures, so thats why I chose XPS. I'll consider Polyiso for walls / ceiling though, and I'm planning on using Armaflex in the hard to reach spaces (and oddly shaped parts like the wheel wells).
Yes, the battens are pressure treated. I thought that would be better for mold protection, but then again, I don't know these this very well, so my very simple logic thought PT must be the way to go, since the price was almost the same anyway. I did not think of any reaction with fasteners to be honest..hmm. I'm anyway planning to fasten them with Sikaflex, not making any holes in the floor (I'm keeping the bulkhead, so I have that extra protection anyway in case of an accident).
As for the battens, the idea was to have a solid base to mount the interior into. I've also seen every other youtuber do this, so I guess I did not think of leaving them out.
The only drawback using XPS under your floor is the ability for that insulation to telegraph noise “squeaks”. It is simply less “squeak resistant” than polyiso.
Roof & Walls; I use polyiso as IMO there is less likely chance of polyiso absorbing liquid water. In my 2021 build I will use foil face & aluminum foil tape the raw edges. Walls & Floors in direct sun & in hot climates can really heat up (also depends on your van colour & roof mounted solar panels). Polyiso performs much better than XPS for high temp heat. Polyiso performance drops off at the opposite spectrum “extreme cold”. For the climate my van will “live” it makes sense to use polyiso in walls & roof. YMMV.
Regarding “seeing others on Youtube”; I understand the human nature. You have stumbled upon & become a Forum Member. I have a bias towards “The Forum”. IMO for Promaster(ish) van builds this Forum” is “The Place To Be”. I post a lot of “crap” on here & some of it might even be right. This is the only van forum I am on (actually it is really the only forum I visit). I think it is a good idea to look at Youtube for ideas, but I think it is very prudent to vet those ideas here. There are many experienced science based DIYer Members here & a mountain of knowledge, albeit sometimes contradictory but that is the great thing about this forum it is a wonderful venue to share opinions & back them up with Science & Logic (rather than emotion).
You can use your build thread here to your advantage (if you wish), but posting questions on your intended design prior to building & obtaining opinions/ideas to assist you in your design. You are Design/Building a DIY van 1st time? It ain’t the building that is hard (exception back aches), but the Design.
The Forum Membership has a wide spectrum of; Architects, Engineers, Scientists, Construction Types, Mechanics, & Much More - Most willing to help you out. All ya gotta do is ask 😁👍
I have a 2021 build thread started months ago (van #2) - I ask for advice on it. Wish I was a member when I built my 2018 as it would have saved me some errors & 💸💸💸.