Re: This is why wood should not be used in a RV
Well, there are two issues here.
1. The bad water valve in the video that flooded the RV with poop when the owners were away, causing the loss, and
2. The issue of wooden building materials you raised.
1. As far as the flood, I don't recall if the host indicated whether the owners were hooked up to campground pressure, or if the leak was dumping water from the fresh tank into the toilet via the onboard pump. It can be argued that there is no reason for anyone in an RV to leave their water pump on when they are away, or even when sleeping. They obviously were not hooked to sewer, but that does not mean they were not hooked to water and electric at the time.
I am even leaning toward the idea of a foot pedal under the sink(s) to enable the water pump when needed, and a timer for the shower. Twist the knob for how many minutes you expect to be in there. Of course, a pressure tank (if installed) could push out a bit of water through any leak before the pressure drops to zero, but it's not emptying your entire fresh tank.
2. I still see pros and cons with each of the construction material choices. Obviously, the experience of repairing the water damage to the walls in your neighbor's cabin is fresh on your mind.
I have wired buildings with metal studs, but have never constructed with them. I am concerned about their strength in non-engineered directions. I think I could probably bend one over my knee, but I don't know as I have never tried it. To explain what I mean, I can stand on an empty cardboard box if I carefully set my feet straight down on the corners so that my weight goes straight down the sides. But if I put my foot down in the middle of a box on its side, it collapses into a heap. I am worried about abnormally strong winds buckling a wall built with steel studs. It seems that lately we are having "500-year" weather events every 10 months in North America.
It is my SWAG (Scientific, Wild A**ed Guess) that the steel studs are engineered so that the interior sheet rock and the exterior sheathing create a "uni-body" system with the components supporting each other. We probably all know how weak (and what a mess) wet sheet rock is. But I haven't studied the systems, so I don't know. What I do know is that a steel stud will make more of a thermal bridge than a wooden one, although they are thinner in the depth direction and could take more of a sprayed insulation between them. The other part of the argument not mentioned here is that it's almost impossible to find straight wood as opposed to 50 years ago.
Concrete is solid, and depending on where it is used gives the advantage or disadvantage of having a lot of thermal mass. But I see them chipping up concrete bridges everywhere because the reinforcements inside have rotted away. One member here mentioned a new paint or coating for reinforcements that will prevent the rust, I don't remember which thread it was mentioned in. But walking on concrete floors can be hard on the body, though most of us do it, at least at work. The spring in wooden floors helps cushion our footsteps a little.
And concrete does not flex at all, it cracks. If a building moves at all due to the ground either settling or drying out, you have a cracked wall. There was a concrete block utility building I used to be involved in at work that had opened up a gap so big, a co-worker commented "you could throw a cat through (the wall)." And the added weight makes settling more likely than with a framed structure.
Stone has been a solid choice for construction as long as we have history. We have some stone houses locally that date to the 1600s and survived the Seven Years War/French & Indian War. Roman roads and bridges have lasted 2000+ years. Ruins of cathedrals in Europe have stone walls standing after centuries even where the roof timbers have long since rotted away. The pyramids are still standing, too.
I am as concerned about insulation and economy of heating and cooling as I am with rot. For the moment I will set aside earth-sheltered housing ideas and keep the discussion above ground. I notice they have been making walls thicker for more strength and insulation since my grandparents' day (2x6's instead of 2x4's), but there still is a thermal bridge. My tendency would be to have an exterior wall framework of 2x4's, and an interior wall with the studs offset so they do not line up with the exterior ones, so that each set of studs faces insulation.
So, suppose I have just won the lottery, and am about to build a small cabin, money no object. I construct the outer wall with metal studs. For exterior siding I use the fake cabin logs made from concrete that they sell in Kentucky or Tennessee, I forget which. Under the siding I install continuous metal window screening for EMP protection. Inside on the south wall, I spray the porous concrete insulation to fill the space between the studs and create a thermal mass that will hold the wall temperature in winter, and slow the heating in summer. On the north wall I just spray foam, and consider the east and west separately based on the amount of sunlight the lot gives them.
Then I install another wall framework offset from the first, probably with wooden studs, and put in conduits for wiring. I spray foam insulation in this area. Then I either notch the studs, or put a third set up, and run radiant PEX horizontally around the walls to supplement the radiant heat in the floors. A thin layer of sprayed concrete insulation as a thermal mass to distribute the radiant heat, a vapor barrier, and then perhaps pine or cedar boards for the interior walls. But I don't buy lottery tickets, so this "ain't going to happen."
A bit of a mad scientist, no?
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.