Permitted development confusion 200mm setback loft

[Emmerski]

Does anyone understand what the following bold and underlined actually means please...?

 

the enlargement shall be constructed so that –
(i) other than in the case of a hip-to-gable enlargement or an enlargement 
which joins the original roof to the roof of a rear or side extension –
(aa) the eaves of the original roof are maintained or reinstated; and
(bb) the edge of the enlargement closest to the eaves of the original 
roof shall, so far as practicable, be not less than 0.2 metres from 
the eaves, measured along the roof slope from the outside edge 
of the eaves; and
(ii) other than in the case of an enlargement which joins the original roof to 
the roof of a rear or side extension, no part of the enlargement extends 
beyond the outside face of any ex noternal wall of the original 
dwellinghouse

[Temp]

It means..

 

"If its NOT one of these two things...

1) a hip to gable 

2) Junction between roof on an extension and existing house

Then the following applies.."

 

So for example a dormer window is neither of these two so must be set back from the eaves by 0.2 meters.

[Big Jimbo]

I generally means that you can build your dormer off the wall below. The soffit and facia of the existing building will normally give you the 200mm you need. I would do you a simple drawing, but i am utter rubbish on computers. What you can't do is join the dormer onto the wall below and have it all as one flat face.