The property is listed or within a conservation zone you will almost certainly require planning permission.
Roof balcony planning permission.
As such they shouldn t need planning permission but there are a few exceptions.
However if you are completing any further renovations to create a physical balcony or terrace you must contact your local authority to gain planning permission.
This is especially the case in conservation areas or where there is no precedent.
In uk the answer would mostly be yes because raised platforms are not permitted developments.
The juliet balcony has a floor no matter how slim it will be considered a raised platform and will need planning approval.
People who would like a balcony also wonder if it will need planning permission.
The dormer may well be permitted development but accessing the roof to use as a balcony is not.
Architexeter 12 dec 2013 2.