Build a smaller room on the roof about one or two squares from the edge of the building.
How do you build a roof in sims 4.
Do this in game using the half hipped roof.
Keep dragging until you are happy with the length.
Although it is entirely possible to get this to look good it looks nowhere near as attractive as using one of the new roof pieces.
Adjust it to be flush against the wall of the room and pull it up to the same height.
Houses coming soon.
One of the biggest problems with building a tower in the sims 4 was that you were often forced to use a 4 sided roof piece.
Just add you would with the existing roof styles to extend the eave simply click and drag the small downwards facing arrow on the side of the roof.
Best built on square or rectangular buildings start with a room on the roof level two or three squares in from the edge.
Quik tutorial how to make a flatroof in the sims 4 as for now you cant use the cheat constrainfloorelevation false like in the sims 3.
If you like a more classic second empire look to your home you can try building a mansard roof.