I'm enjoying capturing these interlocking roofs. Looking at these just on plain paper, I can imagine the painted sky behind. Chalky grey-white, with darker blue and red under-painting showing through. The roofs picked out in payne's grey, and the telephone wires just sliced through the paint with a sharp point.
I've also had the idea of glueing torn paper in strips across the canvas, then painting over that to add subtle texture to the sky.