yeah thats what i meant the opening... 3 meters,, that rules out my plan. Iv got a soil pipe that looks like its going to have to come up the side of a dormer window and look a bit naff i was looking to see if i could move it around the corner and not go as far but its within 3 mt
I think you have misunderstood Rich's post.
The pipe does not need to be 3m away. It can run directly adjacent to the window, or as near to the window as is practical.
What the reg's state is that if the pipes' proximity to the window is within three meters then that pipe needs to finish at least 900mm above that window. If it is greater than 3m then it can terminate lower.