The bald-face hornet is not really a hornet but a wasp. They are all black with white markings on their all black face. They use their mouth parts to scrape wood from dead trees and logs and wooden furniture and wooden siding and mix it with saliva and shape it into paper with their feet. Inside are horizontal layers of cells where the eggs are laid and the larva are raised.
I cannot find information to verify this but in thinking about how the nest is enlarged, as they add more layers to the outside, they must remove them from the inside so that the internal chamber is enlarged so that the layer of cells can be enlarged.
They are reputed to be aggressive defenders of the nest and since this nest is along the end of the house that faces the driveway, the only way to get to our back door, I suppose we should spray it. It will be with great reluctance that I do so, and only after I consult a few more experts to help me decide.