[Working detail 26.05.11] Typical external facade section for museum extension
The ‘stack’ of new spaces and their contrasting relations to the views and garden consist of blind gallery walls uppermost, gauged openings to double height intermediate levels, transparency at the garden level, and give rise to the tripartite arrangement of the wall section.
Given the floating nature of the extension, I ruled out the use of stone, which is so well articulated and logical on the classical building, with its rusticated base carrying the load of the building fabric, terminating with the delicate silhouettes of the stone urns. The compatibility that glazed ceramic and glass offered seemed a good way to work from the blind top wall (ceramic) to the lightest possible veil of glass at ground level. The mediating middle level is, consequently, a combination of the two, with the glass providing a protective screen to the large-scale container of the Holburne collection.
The ceramic panels were the largest the manufacturer could produce, necessitating a wall thickness of 50mm. To avoid creating a grid, I envisaged from my earliest sketches a series of ceramic fins that at the upper level would conceal the vertical joint and at intermediate level cover the posts that carry the outer glass skin.
The laminated, low-iron glass veil is free of complex jointing, creating apparent lightness. With the inner glazing at ground floor, it forms a triple-glazed wall that ventilates to reduce heat gain. The layers of reflection on the skin of the building in its foliate setting and the depth of the ceramic glaze (achieved with two slip coats, single-fired) are intentionally ambiguous. Ambiguity was an element of the architectural order of the building in the artificial condition of a garden setting within the town. The orientation of the original building reinforces this difference – sunlit to Great Pulteney Street and shadowed in the garden.
Eric Parry, principal, Eric Parry Architects
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