In the UK, there are 5 main loft conversion types. Depending on the existing structure and shape of your roof should define which conversion you opt for.
Dormer Loft Conversion Flat roofed and protruding out from the existing roof. Dormer loft conversions are a simple and cost effective method of gaining more space.
Mansard Loft Conversion Mansard Lofts involve altering the roof structure of a sloped roof to a near vertical posture. The remaining roof remains flat. Common among terraced houses and spanning gable to gable.
Roof Lighting The simplest of loft conversions employs turning part of the roof into a window and reinforcing flooring. Electronics and plumbing can be added to make the area habitable.
Hip to Gable Conversion Turning a bungalow or semi-detached house loft into a useable room by straightening slanted end of the roof into a vertical wall, providing good internal space with full head room.
Modular Conversions Assembled off-site, ready made conversions involve a steel frame being craned into position