Dormer loft conversions add additional floor space and extra full height head area, they normally fall within permitted development except for front dormer conversions. Different types of dormers below:
Large flat roof dormers generally go to the rear or to the side of the property:
Small pitched roof dormers would always go to the front for planning approval, but are also used for the side or rear to fit in with the type of character of your home or to fall in with any planning/permitted development removal.
Many semi-detached or end terraced homes have a hipped roof to the side limiting stair access to the loft, therefore what is called a “hip-to-gable” in the industry is constructed, forming a new full height gable wall increases the loft area and allows access for new stairs at that side of the building. Often rear dormers are added with this type of conversion and most come under permitted development too.
The easiest way of converting your loft is with a standard Velux (in line roof window) loft conversion. These work well for very large lofts but can be limited with stair position on occasions. Almost all come under permitted development.
Mansard roofs are less common and are very large, they will require planning permission and the roof has a dual pitch.