Types of conversions
Velux (or roof light) conversion. Generally cost effective and does not normally require planning permision. The Velux (or similar) windows are fitted flush and do not require extensive alterations to the roof, which helps to keep the cost of the conversion down. As the loft is not extended beyond the original roof line planning permission is not normally required (although we do of course ascertain this point before proceeding with any works)
Box dormer conversion, allowing for additional floor space and headroom within the loft conversion. Normally constructed at the rear of the property, they 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.
Hip to gable conversion involves carrying out 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. The new gable wall can be built in either masonry or studwork. As a general rule, houses with hip roofs tend to not have enough internal overall space for a conversion to be practical, so a hip to gable conversion is often the best solution. Once the roof has been extended, the conversion is normally completed with either velux rooflights or a dormer (or possibly both).
As a hip to gable conversion changes the outline of the roof, planning permission may be required. Brentwood Lofts would obviously determine this from the outset.
A mansard roof has two slopes; the lower slope being 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.
Although common on older properties, Mansards are not often seen in the suburbs. Flat roof dormers tend to be a more popular choice for the ‘average’ 3 bed semi or terrace house, due to the reduced cost and simpler construction. A mansard loft conversion will almost certainly require planning permission.