We can use the same attach top base tool to tidy up this junction.
Revit roof secrets.
Please like this video.
Revit then makes the wall meet the underside of the roof correctly.
Using shape editing tools.
See hd version of video tutorial here.
Then choose attach top base 2 and finally select the roof 3.
To turn a sloped roof into a flat roof select all roof boundaries purple lines and uncheck defines slope in the option bar.
I believe this tools are not design for this purpose.
This is the easiest way to do it.
Once again select the wall first 1.
Download manufacturer approved bim content for roofs.
Discover free revit bim objects for roofs.
Roof by footprint can be used for both flat and sloped pitched roofs.
But i m not really sure if this is a best practice.
2 activate slope to create a sloped roof want to create a sloped roof.