Materials Durability
Service life performance of wood in construction Ed Suttie reveals how a new project is calculating the durability performance of wood.
W
hen we buy a house, it is rare that we scrutinise durability aspects of performance in relation to how long the whole, or components of the whole, will last or function. We understand a need for upkeep and maintenance, and we may make decisions based on perceptions or experience and avoid surprises by engaging a professional surveyor or take comfort from new home warranties. In the construction industry, we need to understand durability to design a house, which raises the question ‘How long does a house last?’
What is a forever home? Victorian houses, among others, have transitioned into our national conscience as an important part of our urban landscape, many afforded conservation status, and as
such they might last ‘forever’ as we invest significantly in maintaining and upgrading them. However, many house types, and perhaps many new-builds, may never be valued as conservation-worthy, through loss of functionality or undesirableness, and be lost sooner, such as a poorly designed post-war housing development that is demolished after only 40 years in service. More empirically, whole building environmental assessment methodologies, for example BREEAM1 and the former Green Guide to Specification,2 set a lifetime for a home that reflected the study period for the life-cycle assessment (LCA). This lifetime was set as 60 years, a little more than two typical mortgage cycles. This enabled comparison of environmental impact for components that may be used for the same function but which are made of different materials, and with different maintenance and replacement intervals.
Orientation on the performance of wood, understanding service life of wood in buildings. Photo: Ed Suttie
www.trada.co.uk
The service life of the components (windows, doors, floor cassettes etc) therefore became the focus of interest and significantly affected environmental assessments such as LCA, and latterly environmental product declaration (EPD). A component that needs to be replaced twice in the 60-year study period would have a much greater lifetime environmental impact than a component that only had to be replaced once, or even not at all, during the 60 years. >> Timber 2021 Industry Yearbook
| 93
