Thanks Alex for the WSSI_Teddy_Boen PDF, that's going to allow me judge the quality of the Rubble Stone foundations later on.
The problem with a plastic sheet damp proof course is that you have to leave gaps in the plastic at each corner, and at anywhere else a vertical steel reinforced concrete column rises up from the foundations. Or, if you have a complete damp proof course of plastic then you cannot have the house connected to its foundations by steel rods.
I agree with this and, like Markit, am worried about the implications in case of earthquakes. However, I'm going to take the middle road and just do what I can without changing the construction process.
I'm going to cut a 10cm strip of Karpet Talang and place this between the foundation beam and the first row of red bricks to stop (or at least lessen) rising moisture. I'm also going to cover the earth/back fill with Karpet Talang before the "lantai kerja" and the slab cement are set. I'm not going to attempt to join the two however, so it won't actually be one big sheet of plastic, I'll cut it to fit each specific area that is demarcated by the foundation beams. In this way I can at least feel I did
something to mitigate the problem of rising damp without risking unintended problems in the case of earthquakes.