Use slope arrows to define slopes on a roof, such as a 4-sided gable roof. 
You can use 
  slope arrows to create slopes on a roof. For instructions, see 
  Creating a Sloped Surface Using a Slope Arrow. 
The following example shows a roof that you can create in 
  
Revit using a slope arrow. 
  
 
Creating a Roof with Different Eave Heights
 
   You can create a roof with slope-defined lines at different elevations by joining 2 separate roofs. 
Tip: This procedure works best with a multi-level building. 
- Create a footprint roof sketch similar to the following: 
  
 
- On the Properties palette, specify a cutoff level for the roof. For example, if you are sketching the roof on level 2, you might specify level 4 as the cutoff level. 
- Click 
   (Finish Edit Mode). (Finish Edit Mode).
- Create another footprint roof sketch at a higher level, similar to the following: 
  
 
- Click 
   (Finish Edit Mode). (Finish Edit Mode).
- In a 3D view, select both roofs, and click Modify tab Geometry panel Geometry panel  (Join/Unjoin Roof). (Join/Unjoin Roof).
- View the 2 roofs in a plan view: 
  
 
  You now have a single roof with different eave heights. 
    Finished house in a rendered view 
Creating a Four-Sided Gable Roof
 
   Use slope arrows to create a 4-sided gable roof. 
  
 
- Create a rectangular footprint sketch, and designate all sketch lines as non–slope-defining. The reference plane in the sketch indicates where the 4 sided gable roof stops.
  
 
- Click Modify | Create Roof Footprint tab Draw panel Draw panel  (Slope Arrow). (Slope Arrow).
- On the Properties palette, select New <Sketch> from the filter list. 
- Under Constraints, for Specify, select Slope. 
- Under Dimensions, for Slope, enter 9" (or the metric equivalent). 
- Sketch slope arrows as shown. 
  
  Note: The longer edges of the rectangle are split at the reference plane before the slope arrows are added.
   
- Click 
   (Finish Edit Mode). (Finish Edit Mode).
- Open the roof in 3D. 
   Completed roof 
 Completed roof on a model