Sorry for my lack of clarity, I was talking about both types of roofs, since the classic Somerville triple decker has a flat roof, and the classic Philadelphia a pitched roof with shingles. I was wondering about the former since I've never seen one as such, aside from some one story commercial ones when I lived in a higher adjacent apartment.
And thanks for the comments, you've saved me some research when it comes time to replace my roof.
And thanks for the comments, you've saved me some research when it comes time to replace my roof.