More modern houses have roofs with A-frame structures that are manufactured off-site. The rafters in A-frame roof structures are supported by a number of trusses or struts throughout the roof space, causing an obstruction and major obstacle in a planned conversion. This problem is not insurmountable but will involve installing supports for the rafters to replace the obstructing trusses. Cutting and removing trusses can affect the structural stability of the roof and must never be undertaken without professional advice.
The popularity of loft conversions has resulted in some house builders substituting A-frames with attic trusses. Made from larger timber sections, attic trusses are designed to support the roof and floor loads while leaving a clear area in the roof space for any future conversion.
You will also have to decide which of the three types of loft conversion is most suitable for the roof of the property.
Roof light – this is the most popular type of loft conversion and involves installing windows into the roof that run flush with the roof’s pitch or slope.
Dormer – a dormer conversion is recognisable by a structure projecting from the pitch of the roof which accommodates the window. The roof of the structure can be pitched or flat and ties into the existing roof. Constructing a dormer window in an existing roof is highly difficult, requiring professional advice and assistance.
Mansard – the least common, a mansard loft conversion is generally used on properties with roofs that have a very shallow pitch. Properties with a London roof – named after a style of roof commonplace in the capital – a mansard loft conversion is the only option. This is because a London roof will comprise of two planes that rise from a low central gully to higher eaves at their edge.
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