45 degree rule

[wxy234]

I wish to enquire where the 45 degree rule is measured from for the vertical plane? Is it the window sill, the same base height (850mm) that right to light is measured or the centre of the window.

This measuring point will determine whether the 45 degree line clears or cuts across.

Are there regulations that I look up?

 

[cjard]

As far as I know the "45 degree rule" isn't a rule per se, so it's down to how your council decides these cases
http://www.planning-applications.co.uk/righttolight.htm

 

[freddiemercurystwin]

Yes each LA applies either none, some or all of the guidance from the 45° rule so you should establish what rules your LA have adopted before getting your calculator out. Or have you established that already?