You can use the Roof by Perimeter tool to automatically insert a roof over the perimeter wall layout of a selected building location. If you have a two-story home where the ground floor wall layout is different than the upper story wall layout, and you want each story to have its own roof, you will need to insert a roof on each location. Example
By default, the roof is inserted directly on top of the walls of the current building location. You can edit the support height as well as change the roof’s style and dimensions.
To insert a roof over an entire wall layout:
Make sure the current location is the location containing the walls you want to insert the roof over.
Select Insert > Roofs > Roof by Perimeter, or click the Roofs button on the Building toolbar and select Roof by Perimeter.
In the catalog, select the roof type you want to insert. Note that the catalog does not contain gable roofs. If you want to create a gable roof, insert a hip roof first, then convert it to a gable.
Click inside the wall perimeter. The roof is inserted automatically.
Note: If a roof already exists on the current location, it will be deleted.
Note: If the roof you are inserting runs up against any upper-story walls, the roof will cut around the walls. You can adjust the roof to avoid saddle situations, or to ignore the walls. See Changing the Way a Lower-Story Roof is Created.