Peter Mckinlay wrote:
Your only real problem is roof rusting out. This is overcome by using concrete. The cheapest roof making method is leaving it round, a square house don't care what shape roof it sits under.
Construction, plastic sheeting is laid out in the hole of depth where the roof shall rest. Reinforcing rods/mesh is then laid on top which is covered by concrete. An air hose under the plastic to its centre then begins receiving air causing the concrete to bulge upward. When the desired dome is reached the pressure is held to the concrete cures. Further concrete is then spread over the dome to required thickness.
After this further excavating happens providing the living space and leaving the roof edge sitting on its earthen ledge.
Peter Mckinlay wrote:Hello Len,
We used builders plastic which is polythene in a roll. Overlaid the edges with aquahere glue, but not sure that needed.
Cant help much more than that other than put a soccer ball or other in the middle before air pumping to start the rise.
My personal view is if you want something to be dear as possible take it to a engineer so they can show you how complicated
they can make it as proof of their smarts.