Roof problem

[Paopao]

Hi there, I wonder if you could help me: I have a problem with a subtraction operation on a roof. I just want to cut part of a roof (yellow area) without it changing properties. I click on the roof and use the subtract from polygon operation but the roof change shape (bottom image). It was fine until yesterday, on an old model, yesterday I had to deleted the roof and create a new one and this problem appeared. Anyone can tell me what I am doing wrong and how to achieve what I want?

thanks for your help,
Pao

[Paopao]

I have sorted it by extending the eves overhang, chopping out the bit I don't want and adjusting the overhung back to 0.

[Barry Kelly]

Paopao wrote:
I have sorted it by extending the eves overhang, chopping out the bit I don't want and adjusting the overhung back to 0.

Yes you have to make sure you are editing the roof perimeter line and not the pitching/pivot line.
If you have a zero eaves overhang then temporarily separate the two lines as you have done.

Barry.