On the anchoring of timber walls to foundations: available strategies to prevent wood deterioration and on-site installation problems

Abstract

Experts are aware that the critical and until now unsolved problem of timber wall buildings lies in proper anchoring of the structure to foundations. Geometric inaccuracies and discrepancies between the concrete surface and the timber structure often lead to incorrect alignment of walls, which is normally solved with provisional and inaccurate solutions, in contrast with prefabrication. However, the most important issue is the compromised durability of timber due to rising dampness and fungicide attack, which are a result of inaccurate waterproofing as moisture is absorbed and trapped at the wall base. Difficulties in restoring such damages arise together with maintenance costs of the structures. This work provides an overview on the crucial problems that affect the anchoring of timber structures to foundations. Disadvantages of traditional techniques are presented and critically discussed. An innovative aluminium bottom rail designed for Cross-Laminated Timber, light-frame and Blockhaus technologies is presented, evidencing main structural properties and capacities in assuring timber durability and long-lasting fixing. This aluminium beam is made of an extruded profile with shape and size optimized for load-bearing capacity and lateral stability. Special grooves at both sides are designed to obtain fast and efficient fixing of shear-resisting plates and hold-downs. Main results from latest experimental campaign are given to characterize the system in terms of load-bearing capacity and case-study applications in newly-realized timber buildings are presented. Finally, a proposal for possible restoring intervention to replace the damaged timber at the base of the wall is hypothesized.