We don't have much money, but at least we 'have a roof over our heads'. [=at least we have somewhere to live]
You'll do what I say as long as you're living 'under my roof'. [=as long as you are living in my house]
We hope to have sales and service 'under one roof' [=at the same location] in the near future.
(..) Police officers who haven't seen daylight in months. What about the bomb? Satellite can't pick up any... radiation hot spots. They keep it on a truck. It must have a lead-lined roof. - They-they move it constantly. - Good. So you know the truck? Well, it's one of three. We've been tracking it. (..)2012 The Dark Knight Rises
(..) After your father died, Wayne Enterprises set up different defense subsidiaries. For years, I've been shuttering and consolidating all the different prototypes under one roof. - My roof. - Why? Keep them from falling into the wrong hands. Oh, now you're just showin' off. (..)2012 The Dark Knight Rises