When editing the roof sketch select the edge or edges you would like to slope and select defines slope on the options bar.
Revit make a flat roof.
Add roof lines with a slope and an overhang defined.
Create a sloped roof in revit step 1 draw your roof step 2 define the slope.
Your now have a flat roof.
Attach interior walls to the roof.
In the drawing area angle icons identify which lines of the sketch define slope.
To create a sloped roof in revit modify the footprint sketch of the roof by selecting and specifying the slope defining edges of the roof.
Select toggle slope defining for each line of the roof outline.
Select the lines of the roof outline and right click over the line.
Let s start off with a flat roof first.
The second option in the list is toggle slope defining.
This option turns off the roof slope extrusion for the line.
Make sure you have selected roof by footprint from the drop down tools.
You can also use toggle slope defining on only a few of the lines to create different roof profiles such as a gable.
Select the architecture menu and then roof.
Get this revit file here.
You need to make sure you are in a floor plan view in order to use the roof by footprint tool.