Coppiced sweet chestnut in the construction of imperfect gridshells from asymptotic curves

In recent years, bending-active gridshells with asymptotic geometry have been successfully constructed at the architectural scale. These have typically used materials such as steel and machined timber, with thin rectangular profiles and predictable characteristics. This paper investigates the use of locally sourced sweet chestnut ( Castanea sativa ) in a green untreated state for forming such shells, highlighting the benefits but also challenges that come when working with imperfections. Two demonstrator projects are described, both with identical geometries but differing scales: a proof-of-concept test structure formed from pseudosasa japonica bamboo, followed by a larger structure made from coppiced young sweet chestnut stems, each achieving differing levels of success. The accuracy and predictability of idealised digital models is discussed, alongside the physical reality of working with materials that possess inconsistent profiles, material properties and deviations from perfectly straight elements. In doing so, the potential of constructing imperfect asymptotic-like curved grid structures from untreated materials is investigated.