Reciprocating timber roofs are a method of framing timber, normally in the round, that are not necessarily a permanent structure but are so innately beautiful that I wanted to do a section about them.
The walls structure either it be framing, straw bale or tyres etc are built up in a circle and The round wood beams are laid one by one in a circular arrangement, each one on top of the last, with the final beam resting on top of the first. Once complete it is not possible to see where the construction started or ended as the whole structure forms a continuous circle around a central skylight. This simplicity is aesthetically pleasing but also means that each pole has exactly the same forces acting on it as all the others ensuring that the weight of the roof is spread evenly across the whole structure.
The roof (and possibly walls) at this point are just framed and need to be filled to complete this structure. With a structure like this the walls can be filled in a variety of ways to suit the preferred style, some possibilities include straw bale, cob, cordwood or glass bottle or combinations of any of the listed but typically the roof is laid using straw as insulation with a waterproof membrane placed on top of it to keep out rainwater.