I was just going over the initial calculations and it doesn't actually take into consideration either the inner or outer sheet metal. I suppose they fall under radiant heat transfer?
It appears we will
need an infrared heat gun after all.
Originally Posted by austin1989us
I don't see much of a benefit when it comes to heat transfer.
The benefit for insulating the inner wall is this: it all adds up. For those who are interested in putting the time into having a long-term build and a well insulated space it makes sense. We can (affordably) insulate the dead space between the sheet metal while dealing with other notorious problems. We can reduce radiant and convective heat transfer in that zone to nearly zero. Then we can do the necessary
step of insulating over the ribs. It's all accumulative.
I insulated between the ribs 3.75" thick and over the top of the ribs 1" for a consistent, flat insulated envelope to work with. Of course, I haven't tried the bus with only 1" XPS or spray foam over the entire inside, but from other jobs I've done in more favourable conditions I know that only 1" of XPS doesn't do a whole lot, though it's a nice addition to the outside of a building to reduce those accumulative thermal leaks. This bus I can use in the winter without a problem (our Canadian winter). The ribs and windows are still the weak point, but in its current state it does a great job while maximizing the available floor sq/ft (those oh so precious inches).
With the intention of creating a long-term livable situation... well, I just couldn't imagine NOT pulling those panels off, cleaning and insulating.
A short term metal tent? Just glue XPS over everything, then 5/8" plywood over the XPS with strategically placed screws to hold it in place while the glue dries and make sure it ain't going anywhere down the road. Another thermal bridge with the screws, but you can't win 'em all.