There are two types of roof and they are defined based on where the insulation is placed.
Cold Roof
The insulation is placed in between and above the roof joists which is ceiling level running horizontally.
Or
The insulation is placed between and underneath the rafters which is at roof level running with the slope of the roof.
Warm/ Dormer Roof
The insulation layer is placed above and sometimes between and below rafters which is at roof level running with the slope of the roof. The term Warm Roof comes from the roof structure being insulated and therefore making the roof structure and attic a warm space.
