A copper mansard roof
The refurbishment of this Grade II-listed nineteenth-century hotel includes a new copper mansard roof which replaces the original two-storey slate mansard. The new roof, providing three floors of bedrooms, is set within the original stone parapet wall and incorporates new chimneystacks to replace the unsafe- originals and new windows fitted into restored stone dormers. A row of new barrel-shaped dormer windows light the top floor bedrooms of the mansard.
To minimise additional weight on the foundations the new mansard structure is a braced steel frame with timber floors. It is clad on the inside with a steel profiled deck infilled with insulation. Rooms are lined with acoustic insulation and finished with double-skin plasterboard.
The copper is a decorative finish; it comprises 500 x 500mm copper shingles hand-cut on site and nailed diagonally with dome-headed nails to 38 x 50mm timber battens, which are laid on tapered firrings. A layer of Sarnafil single-membrane roof covering acts as the waterproof seal to the mansard; the firrings provide a ventilated cavity; they are fixed back to 19mm ply strips fixed through the membrane and heat-sealed.
The ridge of the copper mansard is defined by a horizontal 150mm diameter chs raised on copper angles. Each intermediate floor level is articulated by a horizontal 'set-back' which also helps to reduce sight lines. The external corners of the roof are defined by 450 x 100mm 'fins' of copper, fixed over treated timber formers. Rainwater from the copper roof discharges into a syphonic drainage system set behind the restored stone parapet.