Underdraw

The [roof] had never been underdrawn, its entire anatomy lay bare to an inquiring eye, except where a frame of wood laden with oatcakes, and clusters of legs of beef, mutton and ham, concealed it.

Source: wiktionary

He has the whole of the room underdrawn, with the exception of two bays at one end; he admits plenty of air by the windows in the roof into the triangular shaped space formed by the roof and the underdrawing;

Source: wiktionary

You say for month and months you had been underdrawing? — Always underdrawing and giving up every month. Whatever we drew the officer signed an indent for and we gave up a surplus.

Source: wiktionary

Here was the warrant (or at least a justification) not just for Steig's drawings of people as bodily symptoms but, more important, for his abandoning underdrawing in pencil prepartory to inking in a drawing.

Source: wiktionary