Don't make the mistake of stacking it up there. That is a dangerous proposal. Use the sheeting as you hand it up.
At some point the weight of the ash will cause the roof to collapse.
7/16" osb is good in most areas. Wind storm areas might have to be plywood...not sure.
Bare cable is simply a conductor without a coating, sheating, or covering. It is just bare wire.
It is a barrier to radiant heat.
The most beautiful roof in the worldbook by Kathryn Lasky is the Rainforest Canopy.
Houses in rajasthan have thick walls and flat roofs because of the harsh climatic conditions in rajasthan. These kind of houses help in keeping away the heat and maintaining the temperature.
These days the trussed hip roof is most popular.
I am going to take that question to mean "what was a peasant's roof made of in medieval times?" The most common, and least expensive way, to construct a roof was using a material called thatch. A thatch roof is made of thick mats of dried vegetation such as grass, reeds, sedge, etc. When properly constructed it is water and wind proof, and also an excellent insulator, helping to keep houses cool in summer and warm in winter.
its about two miles thick
Most apple peels are approximately 0.3 mm thick.
A hot tube installed on a flat roof should be alright if there are a few key points addressed first. Is the roof a pre-engineered truss system, if so then you will not be able to do the instalation without significant truss reinforcement. If the flat roof is beam built then there should be little problem as long as the beams are at least 4X12 thick.