BCD 2019

36 T H E B U I L D I N G C O N S E R VAT I O N D I R E C T O R Y 2 0 1 9 C AT H E D R A L C O MM U N I C AT I O N S within them, a new building that was out of scale with the original design intention would likely be inappropriate. RHYTHM AND URBAN GRAIN The rhythm of a street is defined by building heights, massing and the way in which façades are articulated. It is possible for the accretion of buildings from different periods in our urban conservation areas to either contribute to or disrupt the rhythm of streetscapes. In order not to be disruptive, new buildings which are skilfully woven into their context and respect the scale and rhythm of the existing street frontages are likely to be the most successful from a design perspective. To create harmonious conservation areas, the elevational treatment of new buildings is of crucial importance. It determines the way in which a new building will relate to its neighbours and the public realm as well as communicating its use and architectural intent. Urban conservation areas are likely to be characterised by a vertical emphasis where plots are narrow and the height of a building or streetscape is greater than the width of the building(s). This is known as fine grain. Where the plots in a conservation area are large and infrequent this is known as coarse grain. Verticality is expressed not only in a building’s dimensions, but also in individual elements such as fenestration, the roofline, and the treatment of the ground floor of buildings. Given the pressure for the optimal use of sites to provide the most accommodation, larger or longer street frontages may be necessary. In order to maintain a fine urban grain, vertical articulation and proportions can be used to ensure that the new, bulkier building relates to the rhythm of the street, as well as adding interest to the conservation area. COMPLEMENTING OR CONTRASTING DESIGNS Successful architecture can be produced either by closely following historic precedents in a conservation area, or by adapting them or even contrasting with them. Local building forms and details contribute to local distinctiveness, however, this does not mean they must be followed and replicated in a pastiche way. Indeed, in a diverse context a contemporary building may be less visually intrusive than one making a failed attempt to follow the area’s historic precedent. Rather, good new design should seek to incorporate those details and forms into a new development in a way that is innovative but not shouty. In urban areas particularly, new design can become competitive, with new buildings vying for awards and photogenic ‘after’ photos. Usually this is dependent on the new contrasting with the old, but this is only ever successful where the new also complements it. A new building with ambitions of contrasting with an historic area in a way that is sympathetic to it requires considerable thought and execution in its detailing and materiality. Creating a modern and contrasting design is one example of a successful approach, but it should not overshadow the more quiet approach of a design which complements and embraces the historic area or building, without looking to announce itself as the new arrival. MATERIALITY Materiality is linked to the ideas about complementing and contrasting design. Employing the prevailing material palette of surrounding buildings in a conservation area will settle a new building into its context, giving it the same qualities of the existing buildings. On the other hand using a different, but sympathetic material palette will put a new building in contrast with the area. Beyond making clear the building’s overall design intention, the richness of a building lies in its use of materials. The key materials that provide buildings with the means to transcend an off the peg appearance are stone, timber, clay, metal and glass. Traditional, natural and handmade materials provide richness and texture which modern materials, by and large, fail to deliver. Additionally, organic and traditional materials have proven to be durable, and to weather in a way that is pleasing. The rate and relative ageing process of different materials should be an important consideration when specifying them for a new building. Stone, timber, copper and lead all accumulate a pleasing patina as they age which both softens them and makes them more dynamic. Longevity and durability are an area where modern materials fall down, often looking worn and poorly maintained rather than nicely aged. Designed by architects Rogers Stirk Harbour + Partners, the World Conservation and Exhibitions Centre attached to the British Museum maintains its own identity, yet it remains sympathetic to the existing architecture of both the Bloomsbury conservation area and the museum itself. (Photo: Rogers Stirk Harbour + Partners)