Philip Bester van Niekerk

Existing factorized methods for timber decay assessment lack spatial resolution and rely on manual assignment of exposure and detailing factors. This study presents a spatially resolved, factorized framework for decay assessment of timber cladding and decking, integrating wind-driven rain modelling via ray-casting, data-driven moisture prediction, automatic geometry-based surface labelling, and dose-response modelling into a single workflow operating on detailed three-dimensional building geometry. The framework was evaluated on a playhouse using hourly climate data from Gothenburg, Sweden. The moisture prediction relies on a metamodel with inputs of daily relative humidity, temperature and precipitation. Decay dose was computed with adjustments for detailing and ground proximity. The metamodel showed robust agreement with the numerical model under varying exposure to precipitation and board thickness. South-facing façades exhibited the highest decay risk with a pronounced vertical gradient, while vertical north-facing surfaces remained largely sheltered. Horizontal decking showed the highest overall risk due to its greater exposure to precipitation and ground proximity. Contact faces and bottom end-grain received substantially elevated doses. Within individual boards, dose varied considerably. The framework automates spatial decay assessment directly from geometry, eliminating manual factor assignment. The pronounced internal dose variation across board faces demonstrates that conventional single-value-per-board methods significantly simplify risk distributions. This information can be used for model validation against full façade systems and to define appropriate limit states for service life assessment.

1. In 2023, building construction and operations accounted for 34% of global CO₂ emissions (United Nations Environment Programme 2025). Among the recommended mitigation strategies is reducing opera...

With increased focus on sustainable building materials and the growing popularity of uncoated wooden cladding, understanding consumer acceptance of aesthetic changes becomes crucial for sustainable architectural choices. This study investigated consumer acceptance of uncoated wooden cladding in Norway, Sweden, and Germany, focusing on personality traits and perceptions. Using an online survey with 3112 participants, the study found that preference for uncoated wooden cladding was similar (around 20%) across the three countries, despite differences in the prevalence of wooden cladding. A natural consequence of weathering of wood exposed outdoors is greying of the surface. The survey presented participants with images of uncoated wooden cladding with varying degrees of grey discolouration. Participants rated the acceptability of these claddings based on their preferences. Acceptance of this discolouration differed by country, Norwegians preferred intermediate-coloured panels, Swedes preferred darker panels, and Germans accepted all panels. Personality traits measured using the Big Five personality inventory and socioeconomic factors influenced preferences. In Norway and Sweden, those accepting the discolouration of uncoated wooden cladding included introverts, highly conscientious individuals, young people, females, and those with tertiary education. Additionally, in Norway and Germany, openness to experience was linked to acceptance, while strong emotional control was significant only in Norway. This study underscores the complexity of consumer preferences for uncoated wooden cladding, demonstrating that personality traits, in conjunction with cultural and demographic variables, jointly influence perception. The findings offer valuable insights for architects, builders, and policymakers seeking to advance sustainable construction practices while optimising consumer satisfaction in the housing sector.

Construction using timber has seen a resurgence in light of global climate mitigation policies. Wood is a renewable resource, and engineered wood products are proving to be competitive against concrete and steel while having several advantages. However, while the renewable nature of wood in construction is a beneficial property for climate mitigation policies, the process of biodegradation introduces a challenge for service life planning. A review of hazard mapping is presented while developing contemporary hazard maps, occurrence maps and projected hazard maps for 2050 using representative concentration pathways (RCP) 2.6 and 8.5. The risk of timber decay is expected to increase in most of Europe as the temperatures rise, with a decrease expected in dryer regions. Termites are likely to experience a range expansion as more areas become suitable, while human activity and an increase in extreme weather events like floods are expected to facilitate dispersion. Marine borer species already present a risk in most European coastal regions; however, the effect of changes in water temperatures are likely to shift the boundaries for individual borer species. Overall, warmer climates are expected to increase the metabolic activity of all of these organisms leading to a general reduction in service life.

Performance-based, service-life design of wood has been the focus of much research in recent decades. Previous works have been synthesized in various factorized design frameworks presented in the form of technical reports. Factorization does not consider the non-linear dependency between decay-influencing effects, such as between detail design and climate variables. The CLICKdesign project is a joint European effort targeting digital, performance-based specification for service-life design (SLD) of wood. This study evaluates the feasibility of using a semi-empirical moisture model (SMM) as a basis for a digital SLD framework. The performance of the SMM is assessed by comparison against a finite element model (FEM). In addition, two different wood decay models (a logistic, LM, and simplified logistic model (SLM)) are compared. While discrepancies between the SMM and FEM were detected particularly at high wood moisture content, the overall performance of the SMM was deemed sufficient for the application. The main source of uncertainty instead stems from the choice of wood decay model. Based on the results, a new method based on pre-calculated time series, empirical equations, and interpolation is proposed for predicting the service life of wood. The method is fast and simple yet able to deal with non-linear effects between weather variables and the design of details. As such, it can easily be implemented as part of a digital design guideline to provide decision support for architects and engineers, with less uncertainty than existing factorized guidelines.

In this article a dose–response model was developed to describe the effect of soil temperature, soil moisture content, and soil water-holding capacity, on the decay of European beech (Fagus sylvatica) wood specimens exposed to soil contact. The developed dose–response model represents a step forward in incorporating soil-level variables into the prediction of wood decay over time. This builds upon prior models such as those developed within the TimberLife software package, but also aligns with similar modeling methodology employed for wood exposed above ground. The model was developed from laboratory data generated from terrestrial microcosm trials which used test specimens of standard dimension, incubated in a range of soil conditions and temperatures, for a maximum period of 16 weeks. Wood mass loss was used as a metric for wood decay. The dose aspect of the developed function modelled wood mass loss in two facets; soil temperature against wood mass loss, and soil water-holding capacity and soil moisture content against wood mass loss. In combination, the two functions describe the wood mass loss as a function of a total daily exposure dose, accumulated over the exposure period. The model was deemed conservative, delivering an overprediction of wood decay, or underprediction of wood service-life, when validated on a similar, but independent dataset (R² = 0.65). Future works will develop similar models for outdoor, field-trial datasets as a basis for service-life prediction of wooden elements used in soil contact.

Wood is a renewable resource and a promising construction material for the growing bio-based economy. Efficiently utilising wood in the built environment requires a comprehensive understanding of the dynamics regarding its usability. Durability is an essential property to consider, as various types of exposure create conditions for the deterioration of wood through biotic and abiotic agents. Biodegradable materials introduce increased complexity to construction and design processes, as material decomposition during a structure’s lifetime presents a physical risk to human health and safety and costs related to repairs and maintenance. Construction professionals are thus tasked with utilising wooden elements to accentuate the material’s beneficial properties while reducing the risk of in-service decomposition. In this paper, only the cause and effect of fungal induced decay on the service life of wooden buildings and other wood-based construction assets are reviewed. The service life of wood components can thus be extended if suitable growing conditions are controlled. Multiple existing modelling approaches are described throughout the text, with special attention given to the two most comprehensive ones; TimberLife and the WoodExter. In choosing an appropriate model for a specific application, the authors recommend evaluating the model’s regional specificity, complexity, practicality, longevity and adaptability.