Private Fred Dibble demonstrates the scale.
I got to work on the first stage of the roof while the sand coat dried. A sheet of thin card forms the base, with kebob skewers glued to it to provide cross-bracing. I opted for this method since card is notoriously prone to warping, foamcore would've been too thick, and MDF too heavy. Ordinary white adhesive will fix the skewers firmly but they do need to be weighed down to ensure this.
The typical tembe had a thatched roof (and I don't need to point out the problems that would cause in a fortified building) and they appear to have been flat. I've decided to give it a slight peak, enabling it to shed rainwater more effectively and giving at least a chance for any burning objects thrown up onto it to roll off. That will come in the next stage.