Reciprocal Frame Connector

An innovative detail, simplifying reciprocal frame construction.

The beauty of reciprocal roof frames, where each element supports the next in a circle of forces, but no one element spans the full distance, belies the complication of their construction – in particular the cutting of housings where the rafters meet each other around the central oculus.

In partnership with structural engineers Price & Myers, Manifest developed an innovative connection detail which allows for much greater simplicity in construction of these delightful forms.  The principle is based on doubled rafters, held apart by blocking pieces, between which large “dowels” can be inserted to join rafter to rafter (and rafter to post, whose heads are shaped to the same diameter).

The frame shown here was constructed by one person working entirely alone, with the connector detail allowing for adjustments prior to final fixings.  The bolts are drilled through both rafters and dowel only once the final position has been confirmed – but once fitted, and with the outer wallplates to provide further lateral stability, they became a structurally sound ensemble.