hi,
can you please help,we are new to van ownership and conversion and would like some advice on how to line the roof to manily stop condesation .i had thought of sticking some thin ply 3mm onto roof and carpeting over .
any ideas gratefully recieved .
Greetings & Welcome!
First you need to understand that nothing prevents condensation, absolutely nothing.
Insulation, wall/roof/floor coverings, and such only hide it and trap it, and is not a proper way to deal with it. Passenger vehicles are designed to wick the moisture to the interior where it can then be evaporated out. Cargo vans leave the bare walls/floors/ceilings exposed so the moisture can be evaporated out.
So if we wish to cover the walls/floors/ceilings, we need to duplicate one of these methods, or else we will wind up with mold and rust. So you either need to ventilate all the way to the outside skin, or be able to wick all of the moisture to the interior.
Condensation and moisture are one of the biggest problems we have to deal with, which is one of many reasons that I prefer starting with a passenger van van that the has already done all the hard work for us. That being said, there have been two different schemes that I have seen used, that I have actually been impressed with.
One scheme glues open cell foam to the outer skin, and then covers it with a breathable material.
The second scheme sandwiches a layer of thermozite insulation in between 2 layers of thinsulate. This combination also successfully wicks the moisture to the interior, and then with a breathable covering, the condensation and moisture can be evaporated out.
The next thing you need to add into the equation is adequate ventilation, because without that you have no way of evaporating the moisture out. Moisture can not be evaporated out of a sealed vehicle.
Give a shout if you need more.
Cheers!