A mansard conversion explained | Landmark Lofts

A mansard conversion explained

For the second post in our series detailing the various types of loft conversions, we are focusing on the mansard. The term ‘mansard’ derives from the French architect François Mansart (1598-1666) of the Beaux Arts School of Architecture in Paris, France. Although the architect did not develop the mansard roof, he renewed interest in this style of roofing. In fact, Napoleon’s famous project was the extension of the Louvre, which reintroduced the Mansard roof.

What is a mansard loft conversion?

L-shaped mansard

A mansard conversion changes one of the sloping sides of a roof to a much steeper slope of 72 degrees. Generally front or rear facing, it will feature a sloping back wall incorporating windows in the form of small dormers.

This type of conversion normally applies to older terraced properties; however it is also used for flat roof properties or houses which fall within a conservation area. These will have a mansard at the front and rear, creating an extensive converted space in the new loft.

Mansards are commonly built by raising the party/gable walls either at the end of the property to make the profile for the mansard, and then creating the timber frame. It involves replacing the whole roof, unless the house was built in a mansard style.

Will you need planning permission?

Because of the major changes in the roof and structure, mansards will almost always require planning permission, particularly as the brickwork will be raised up on the party walls. 

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