Simon maxwell in order to create the required head height for the staircase but also keep the existing window a unique twisted roof was the answer.
Joining extension roof to existing.
That s a simple low cost solution that can tie in well with the main house.
A lean to roof also called a shed roof slopes in one direction with rafters that rest against another structure at their high end and overhang.
In ni you are allowed to extend your house by up to 70mcu or 15 of the original house volume whichever is the greater if it is detached or semi detached.
To do this we had to extend the plane of the shed roof out over the porch roof creating a small triangular extension of the existing roof.
In the case of a flat roof extension the height of the highest point of the roof must not exceed the parapet or eaves of the existing roof.
How to join a lean to roof to an existing roof.
The bottom of our blind valley was about 30 inches short of the bottom of the porch roof so we extended the line of the valley down to the edge of the new roof.
While it looks like an impressive architectural gesture it is also an effective and practical solution to the problem.