I think the guy has that figured, the truck is completely insulated. He even makes sure to wrap the insulation
in vapour barrier. I actually like the wood roof, if its varnished its not an issue.
Aluminum is cold, sweats. Anyways, many ways to do each thing.
Yeah I agree, but what do you mean with Aluminum sweats? I think you mean the condensation right? I think a clear indication to ventilate more, and it would also happen on the steel parts of the car.
Wood is definitely more cosy for a camper interior. And if you have a normal / big van where weight is not an issue, it is great and easy to work with. I used wood myself, and it allowed me to create a camper interior in a very short time (although I did not cover everything as he did)
However, for 4x4 applications weight is usually an issue. For example, half the overland / travel Landcruisers with all luggage on board are close to their max weight.
With wood, you're trying to find a compromise between weight and strength. I made it quite light, but now it's not so strong. With aluminium you don't really have to find a compromise.
The roof definitely looks nice, makes it look more like a house than a van. But it will not absorb any sound, or at least not better than steel or plastic roof.
Might not be an issue, but if you have a noisy car (and travelers in the back), you can apply a (thick) fabric layer/liner that will absorb driving/engine noise instead of bounce it back.