Fixis refixisque ingentibus stilis. Il legno nella costruzione antica, litoranea e sommersa

The ancient construction in a coastal, flooded or lagoon environment is based on wood. On unstable substrates, wood played an essential role in consolidation, both in ordinary building and in the construction of bridges, the weights of which rest on perennial piles, while any gates to contain the castings have a temporary function. In river and lagoon areas, wood is used as an absolute material for bridges and walkways, or as a foundation piling for stone quays; otherwise, as a timber consolidation of the banks or to create widening caissons, with filling without binders, in which the firmness of the building is permanently entrusted to the carpentry. Wood also plays a temporary or perennial role in cementitious construction in the water, depending on the tasks assigned to it: some elements perform their function up to the hardening of the mortar, while others maintain a stabilization capacity - probably planned - of the works even beyond. The different typologies are examined, with philological exegesis of Vitruvius’ technical terminology, compared with the procedures documented on the structures: in particular if submerged, with the high probability of tracing wooden elements preserved in an anaerobic environment, with the possibility of dating by means of dendrochronology and 14C. To the Vitruvian systems are added foundation methods in the dunal wetlands, and systems of casting concrete in deep waters, based on the use of caissons with the bottom.