16 August 2021

Mansard extensions: a historic piece of common sense on housing


An astonishing chorus of support, including yesterday’s Sunday Times, has already greeted Dr Samuel Hughes’s proposal on mansard roof extensions. He suggests that we revive the fine Georgian and Victorian tradition of upward extension of historic terraced houses by adding mansard roofs in keeping with the rest of the building. Support for the report ranges from the Head of Policy at the Centre for Policy Studies to the Senior Director of the Prince’s Foundation, the former head of RIBA, and the deputy head of Generation Rent.

It beggars belief that – in the 70-year war involving some wanting total deregulation and some wanting completion of England’s near-total ban on building more homes – until today, no-one has explained how mansard roofs can be a sensible way to make progress. Such extensions could potentially add a million new bedrooms, many of which will become new homes in maisonettes, as many mansards already are today.

The housing shortage means many families have fewer children than they would like. Many others are crammed into houses with too few bedrooms, or have a grandparent stranded far away who would love to live in and help with childcare. Housing in many parts of the country is also extremely expensive, compared to the cost of building more and compared to our international competitors. Buying an existing house in Oxford, Cambridge or Brighton costs roughly four times as much as building a new one.

The UK was the first country to urbanise. As a result, much of the housing in the inner parts of our largest and most economically active towns and cities is more than a century old. Unthinking absolute resistance to change from a tiny minority of officials – often blissfully unaware of the resulting human cost – has frozen much of that historic housing almost exactly as it was in 1939. Then, new construction was banned due to the war; controls were continued with the 1947 Town and Country Planning Act. The recent permitted development rights for upward extension – which are in any case subject to council approval in respect of overlooking and design – do not cover buildings built before 1948.

That is entirely not to say, of course, that we should tear down those historic houses. But there are plenty of ways to adapt and add to them in ways that will create better, more attractive buildings, improve the supply of housing to reduce overcrowding, and add more customers for struggling high streets. Dr Hughes’s report, published yesterday by Create Streets, is a brilliant step forward. On reading it, like many of the greatest ideas, it seems so obvious that one wonders why no-one has bothered to write it up before.

Hughes suggests that on rows of terraced houses where there is already a mansard roof extension, the other houses should be permitted to add them to the same height to end the uneven ‘gap-tooth’ effect. On streets where there are none, residents would be allowed to vote to give themselves permission to do so. All of this would be subject to strict design rules to ensure that the streetscape is enhanced, not damaged.

As Christopher Boyle QC, former head of the Georgian Group, notes in the foreword, the Georgians or Victorians would have been puzzled by the very idea that local governments would ever ban such roof extensions. In today’s price environment, they would have added mansard roofs in haste. In fact, in the more unaffordable parts of the country they would have done so many decades ago. Modern bans on such extensions are not only unwise and damaging, but ahistorical.

The idea is backed by modern and traditional architects, by the Chair of the umbrella group of London’s civic societies and by the head of policy at the professional body for planners, the RTPI, together with a long line of other luminaries. It gives a way to help to meet London’s increased housing targets, which will kick in for the next London Plan in five years.

Robert Jenrick, the Housing Secretary, has already responded adroitly to a wave of comments on the Housing White Paper. I trust he will greet this common-sense suggestion with the enthusiasm it deserves. It could easily be tucked into the Planning Bill with a short enabling clause that could allow street votes and block votes – now suggested even by the American Planning Association – to be piloted as well.

Some local authorities are already sensible about allowing well-designed upward extension on traditional terraces. Others – like Islington, next to the City of London and with some of the highest-cost housing in the world – are still stuck in a ‘computer says no’ mindset. That is driven by a few officials, wilfully blind to the patterns of history, who prefer stasis to helping people. It is high time to fix that, while building on our living tradition.

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John Myers is co-founder of London YIMBY, a grassroots campaign to end the housing crisis with the support of local people.

Columns are the author's own opinion and do not necessarily reflect the views of CapX.