Hazleden, D. G. and Morris, P. I.
1999 8th International Conference On Durability of Building Materials and Components, May 30 - June 3, Vancouver, Canada
Hazleden, D. G. and Morris, P. I., (1999), "Designing for durable wood construction: the 4 Ds", 8th International Conference On Durability of Building Materials and Components, May 30 - June 3, Vancouver, Canada.
Abstract:
While there are examples of ancient wood buildings which have stood the test of time, there are also examples of new buildings which have suffered deterioration problems within a few years of construction. Changes in materials, design and construction methods have been suggested as the culprits and there has been a tendency to look for a magic bullet to solve the problem. Recent work shows that a number of factors have combined to cause these problems. The solution has to be equally multifaceted. Although wood is a very versatile building material, designers need to bear in mind its biological origin when using it in construction. Moisture management is the key and, in the temperate rainforest climate of coastal British Columbia, controlling rain penetration is critical. Such control requires defense in depth which can be summarised as 4 Ds: Deflection, Drainage, Drying and Durable materials. In combination, these may provide sufficient capacity to balance the rainfall load. However, it is necessary to provide over-capacity to allow for imperfect design and construction and for aging. Durable wood construction therefore requires 4D thinking in the sense of four-dimensions: three-dimensional detailing, and the effect of time, the fourth dimension, on long-term performance.