Easy
Roof can be easily walked on
without the need for special equipment. (safety gear aside!) Materials can
be stacked on the slope for installation.
| 
Steep
Roof can be walked on but may
need temporary walk planks installed. Materials may also need to be placed
on these walk planks during the installation.
| 
Extreme
Roof may or may not be able to
be walked on. Materials cannot be placed on the roof and will need to be
suspended by crane (or other method) during the installation process.
|