roof with viewing deck

Hi Guys
I have a roof and i need to place a viewing platform in it. i have attacked a few screen shots of what I’m trying to achieve, I keep getting this angle in the corner.
Thanks
Myles
cba duke street.JPG
duke street roof 1.JPG
duke street roof.JPG

more screen shots.
the render is of my first try.
duke street first option.JPG
duke street roof end points.JPG

Hi Guys
this is my solution, any suggestions on how I could tidy it up around the edges?
love using the new roof tools much easier to modify the roofs.
Thanks
Myles
duke street roof solution.JPG