book-2

106 STRUCTURE AS ARCHITECTURE▲ 6.4Chapel interior, facing towards the altar.▲ 6.5Ribbed roof structure.Inside the chapel, the roof support is revealed. Thirty-six regularlyspaced square posts are set out from the interior plywood wall-lining(Fig. 6.4). Each connects delicately to the wall by three steel pins. Thesimple move of withdrawing the posts from their conventional locationwithin the walls and exposing them affects the interior enormously.Acting as visual markers, they modulate the wall surface, but also increasethe shape definition of the interior space and accentuate a sense of enclosureby their continuous alignment with the roof ribs they support.The roof structure possesses symmetry and visual simplicity. The ribbedpattern of rafters recalls the ribs on the underside of a leaf (Fig. 6.5).Whereas conventional roof framing usually comprises a hierarchicalstructure consisting of transverse rafters above a deeper longitudinalspine or ridge-beam, all the chapel roof ribs, including the spine-beamthat does not span the whole length of the chapel, are of identicaldepth, and each branches from the spine to bear on a perimeter post.Thin steel plates, welded together to achieve the branching geometry,are interleaved between timber laminates to achieve a two-way structuralaction. Skilfully concealed, the reinforcement does not detract fromthe glue-laminated timber construction. Further evidence of detailingrefinement is seen in the shape of the spine-beam itself. Not only trapezoidalin cross-section to soften its visual impact, its width tapers inharmony with the building plan, wide near the front of the chapel andnarrow at the rear. These details that reflect the building form and thedesigner’s aesthetic sensibility are indiscernible at the first viewing, but