A "canopy" is typically a flimsy bit of cloth that would collapse under a meter of snow. What you need is eaves, sloped to the side so that the inevitable aval

A "canopy" is typically a flimsy bit of cloth that would collapse under a meter of snow. What you need is eaves, sloped to the side so that the inevitable avalanches don't pile over the bottom steps. That adds cost and complexity to the build, and often makes for a dreary fortress look.