Its been some time.

Sorry I have been doing other things.
I have not given up on underground as the Australian bush fires have proved a point.
Construction of a small shelter can be done by hand with a shovel now that the ground is wet. Dig a small trench 5 feet wide and ten or twelve feet long five feet deep cover the hole with burnt trees  and cover this with builders plastic to a distance from the hole the same width as the hole, that is a sheet 15 feet by 17 feet on a 12 foot by 5 foot hole.
Tamp the hole floor with a wooden hammer holding the handle vertical with an up and down motion.paint with linseed oil and the floor will harden paint the walls with any old plastic paint to stop dusting of the walls. Add door and furniture as required
This shelter will do till a more permanent house is constructed.