Confused if loft conversion comes under permitted development

[Lockdown20]

We're close to deciding to go for a dormer loft conversion but as our house is side on and the conversion comes up to the principal elevation were not sure if this under permitted development?

One side a large dormer will span the majority of the roof and on the other side a much smaller dormer.

In the picture uploaded your looking at the front of the house and the original outline of the house I've marked in blue.

Any clarity would be helpful. Thank you

 

[tony1851]

What you propose would be permitted development, as long as the volume added is < 50m³.

 

[Lockdown20]

Thank you for clarifying Tony.

 

[DevilDamo]

It may be the way that image has been drawn but also make sure the roof of the dormer(s) do not exceed the existing ridge line.

 

[LukeB123]

Definitely check on the ridge height.

I assume that you've just missed the front door, windows etc off the drawing, as I would not say that's the principal elevation even if it faces a road there. I would also suggest that as your house appears to be in a rural location (with rolling hills around) that you aren't in a conservation area or greenbelt, which has further restrictions.

If your comfortable on those points, refer to Tony's advice