Is the roof over a single unit in a multiple unit condominium considered common property?

Read your governing documents to understand the line between what you own individually and what you own with all other owners.

The line is usually described as 'the skin', 'the wallboard', 'the studs' and so forth. As well, your CC&Rs should define in particular what is owned in common within the walls. This definition may cover 'Plumbing', 'conduit', 'vents', and so forth.