High Quality Follow these steps.
1: Setup your room at the specific dimension that you want.
2: Draw a horizontally inclined wall in such a way that
wall thickness = roof thickness,
wall length = roof length in top view(+ if need (extension x 2))
wall height = roof width in top view(+ if need (extension x 2))and
wall angle/direction(important and 30degree recommended) = roof slope/angle.
3: Then go to plan-> Modify walls and apply different color or texture for each sides of the wall.
[*Apply a color is better than texture to avoid adjust rotation later].
4: Now select wall and Tools->Copy as new furniture(additional plugin).
[*You can bypass this step if you are using beta versions or don't have the plugin].
5: Now select 3D view -> Export to OBJ and save as RoofTop.obj file.
6: Import exported RoofTop.obj using the wizard by clicking Furniture-> Import Furniture,
choose model and click continue.
(next window will help to set roof top angle).
click on the arrow buttons to change its rotation(Down & Right for me)
(you can click and drag in Perspective view to see the adjustment that you made).
we need Top view = roof top view.
if yo set it properly then click continue.
Now you can click continue and finish importing.
(You can either set roof height and size or continue by choosing the default).
7: Now overlap room with the roof you imported and edit its width and height like a furniture if necessary.
8: Copy(ctrl+move) roof and rotate it into 180 degree for the other side then Group together and use it. [=D>]
If you want to create a complicated slope roof/celing then refer the Official Link ... #T002
Thank you. [>:D<]
