PD and single storey extension

[mwf28]

Hi,
Just wonder if any body can give me a little advise and technical information concerning premitted development regulations.
I live in a semi detached 3 bedroom house on rear of both houses mine and my neighbours is a brick built lean to which has a flat roof which runs along both properties.
This lean to is a depth of 22 inches.
My neighbours extention foundations run from the outer edge of the lean to by a distance of 3 m.
My question is the premitted development rules of 3m projection taken from the lean to or from the main rear wall of the house.
My reason for asking is as it stands the extension will be projecting out from the neighbours by over 3m if they are allowed to use the lean to as the extension starting point.
This extention will run parallel with the party wall boundary and the height will be the same height as the lean to flat roof.
The extension already under PD rights is practically putting a wall to left of my sight of view from my rear french patio doors.

I told the neighbours I did not mind but it will with the preposed foundations be restricting a fair amount of light into my property.
I would be a little more than pi**ed off if they never added the lean to projection into the allocated 3m.
Many thanks.
M

 

[tony1851]

If the lean-to was original to the houses, the 3m is measured from the outer face of the lean-to. But they cannot 'wrap-round' to join up to the (set back) main rear wall.
If the lean-to was a later extension to both houses, then a 3m extension would need planning permission because it would be going out more than 3m from the original rear wall.

 

[DevilDamo]

And if you decide or want to go more than 3m, you can do so via the Larger Home Extension (inc. Neighbour Consultation) scheme.