relatively light remedial works when damage occurs. More serious problems can, however, arise from water leakage through the roof, façade, or water/heating systems; in such cases, the damage is proportional to the time taken to discover the leaks.
defensive strategies that need to be applied at different stages of the building’s life, including:
Common Perception: Timber can not be exposed to water without sustaining damage. Reality: Timber can handle water exposure as long as it is allowed to dry out properly. With the right design and construction techniques, such as using protective coatings and ensuring proper drainage and ventilation, timber can resist water damage effectively. It is prolonged exposure to moisture without drying that poses a risk, not short-term contact with water. – Design phase: design for durability (eg raising timber from ground level, fall to roof panels etc) – Design phase: Provision of potential water drainage paths (eg roof falls, outlets) – Construction phase: Moisture management strategy – Operation phase: Water/moisture detection (as early as possible through low and hi-tech means) – Geneal: Forsee ways to promote drying of wet timber through drainage, ventilation, evaporation, and diffusion
PREDICTING RISK AREAS
In all buildings, there are areas that may be more susceptible to moisture damage, in particular:
– Roofs and terraces, which should be designed to prevent water sitting on the wood either during construction or in the event of a membrane failure, ie the structure itself should be sloped (the greater the slope, the less risk of water accumulation). – Interfaces between walls/columns bases and ground floor slabs, where infiltration, capillarity rise or even interstitial condensation could cause damage. This can generally be avoided by raising the timber above the finished floor level. – Façade panels, and particularly the interfaces between panels, should be made accessible by positioning them away from the main structure (eg columns, perimeter beams). – Areas around water pipes and wet service routes, which should be monitored by leak and moisture sensors. – Wet areas (eg kitchens, showers, and bathrooms) where there is a risk of leakage and/or malfunction of equipment. This risk that can be mitigated using moisture sensors above protective membranes and in some cases with less sensitive materials than CLT or as floor slabs eg traditional joisted floors, precast concrete planks or steel profiled deck. In all these areas, careful attention must be given to the design of the timber structure to ensure it is well-detailed and allows for easy access, repair, and partial disassembly if moisture-related issues occur. While these problems can arise at any stage of a building’s life, they can be anticipated and addressed effectively during the design and construction phases at various scales.
Effective moisture management is achieved by protecting the structure and envelope using multiple, combined
DURABILITY
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