Mansard roof
A mansard roof, also known as a French or curb roof, is a roof characterised by that fact that each of its four sides has two pitches, the lower pitches being steeper than the upper pitches. It is similar to a gambrel roof but differs in that it displays the same profile on all sides (whereas a gambrel roof has vertical gables at either end). The lower slope is commonly fitted with dormer windows.
Mansard roofs allow for increased space beneath their steeper sides. They maximise headroom inside the upper storey of the building whilst lowering, what would if it were simply-pitched, be a very tall roof. The mansard form can also help water runoff, as the pitch increases towards the eaves, where the runoff is likely to be at its greatest.
When viewed from near the building at ground level, the upper slope is often not visible.
The commonly-attributed earliest example of a mansard roof is the Louvre, designed by Pierre Lescot around 1550. It was popularised in the French Baroque period by Francois Mansart and became widely used during the Second French Empire (1852-1870) as well as in the United States and Europe. One of the factors attributable for its popularity in France was that houses were taxed by height or the number of storeys below the roof. The design of the mansard enabled the creation of an additional floor without having to pay additional tax.
NB The National Planning Policy Framework (NPPF), published by the Ministry of Housing, Communities and Local Government in December 2024, defines a mansard roof as: ‘A type of roof that is characterised by two slopes, the lower steep and the upper shallow. It is generally regarded as a suitable type of roof extension for buildings which are part of a terrace of at least three buildings and at least two stories tall, with a parapet running the entire length of the front façade (reference: Create Streets, 2021, Living Tradition).’
[edit] Related articles on Designing Buildings
Featured articles and news
Villa Wolf in Gubin, history and reconstruction. Book review.
Construction contract awards down £1bn
Decline over the past two months compared to the same period last year, follows the positive start to the year.
Editor's broadbrush view on forms of electrical heating in context.
The pace of heating change; BSRIA market intelligence
Electric Dreams, Boiler Realities.
New President of ECA announced
Ruth Devine MBE becomes the 112th President of the Electrical Contractors Association.
New CIAT Professional Standards Competency Framework
Supercedes the 2019 Professional Standards Framework from 1 May 2025.
Difficult Sites: Architecture Against the Odds
Free exhibition at the RIBA Architecture Gallery until 31 May.
PPN 021: Payment Spot Checks in Public Sub-Contracts
Published following consultation and influence from ECA.
Designing Buildings reaches 20,000 articles
We take a look back at some of the stranger contributions.
Lessons learned from other industries.
The Buildings of the Malting Industry. Book review.
Conserving places with climate resilience in mind.
Combating burnout.
The 5 elements of seiri, seiton, seiso, seiketsu and shitsuke.
Shading for housing, a design guide
A look back at embedding a new culture of shading.
The Architectural Technology Awards
The AT Awards 2025 are open for entries!
ECA Blueprint for Electrification
The 'mosaic of interconnected challenges' and how to deliver the UK’s Transition to Clean Power.
Comments
I love this design!!! I have a home with a mansard roof and I am trying to renovate the front. I am wondering if you know the dimensions of the two windows on each side of the door?