Velux and rooflight conversions are the same, Velux are the leading manufacturer of roof windows and with over 60 years experience producing windows the name Velux has become synonymous with this type of conversion. This type of conversion is generally very cost effective and does not normally need planning permission.
A dormer is an extension to the existing roof, allowing for additional floor space and headroom within the loft conversion. Dormers protrude from the roof slope, normally at the rear of the property and can be built in a variety of styles. Internally, a dormer will have a horizontal ceiling and vertical walls compared to the normal diagonal sides of a conversion. In lofts that have limited space or headroom a dormer will provide additional space that can make a conversion feasible.
A mansard roof has two slopes, the lower slope is close to vertical at 72 degrees and the top section of the roof is almost horizontal. This style of roof is named after a 17th-century French architect Francois Mansart (1598-1666) who used this design of roof on many of his buildings. A mansard roof has the advantage of maximising the available space within your loft.
Hip to Gable
A hip to gable conversion involves making fairly major changes to the roof. The gable wall is built up to the ridge line and a new section of roof is built to fill in the gap. As a general rule, houses with hip roofs tend to not have enough internal volume for a conversion to be practical so a hip to gable conversion is the best solution.