Designed by Arboreal Architecture, Loft Library comprises 40 linear meters of book storage for a two-storey end of terrace house in Walthamstow, east London. Built in the 1980s, the house employs brick cavity walls with a trussed rafter roof. The single pitch of the roof formed a space at one end of the loft, which was not easy to access due to the diagonal members in the timber trusses. The architect decided to work within the fabric of the existing building rather than create a new loft structure or extension, due to the modest budget. By replacing the diagonal truss members with plywood arches the 10-square-metre library and study space was formed with stair access, a small bench, shelves between arches and a study space at the end.
18mm spruce plywood is used for every surface. Templates for the curved arches were drawn in CAD before the plywood elements were formed by CNC cutting service Cut & Construct. They were supplied to the main contractor as a ‘client supply’ item with screw-holes and reference numbers cut into the timber to ensure quick and easy assembly. Spruce plywood was chosen over birch plywood as it was both cheaper and has a more expressive timber grain, says the architect. The fire retardant treatment of the timber surfaces is a non-hazardous, non-toxic, low-viscosity clear water-based product called Flametect C-WD. This was over-coated with OSMO Polyx Oil.
Ground, first-floor and loft plans; sections
Three vertical, triple-glazed windows located between the trussed rafters on the north elevation provide light and rhythm to the library and study space. An additional window on the west elevation catches the warm evening sun. LED lighting strips of 300 lumen per metre were installed in the centre of each bay to illuminate the books and integrate with the rhythm of the arches.
The roof structure was left in place throughout the works, avoiding the additional expense of rain-proofing the construction site. Cost quotations for the supply, cutting and delivery of the plywood arches, staircase, shelves, bench and desk were sought prior to tender, so that the risk of an apparently complex architectural proposal would not be overpriced by the tendering contractors.