A dormer loft conversion incorporates one or more dormer windows. They are suitable for most roofs and, if confined to the rear of the property, can often be done without planning permission. Adding dormer windows to your loft will provide the remodelled loft-space with natural light as well as views out.
A mansard roof is where the slopes of the roof are inclined slightly, typically to 70 degrees. In most cases, planning permission is required. The construction is more complicated and, therefore, more labour intensive. They usually provide more usable space than other loft conversions, which helps mitigate the extra time and costs involved in construction.
In a hip to a gable loft conversion, the hip (sloped roof) is removed, and the sidewall is built up to form a gable. In most areas, hip to gable loft conversions can be undertaken without planning permission. They are often combined with dormer or mansard conversions to maximise the usable loft space further.