Microclimate and moisture content profile measurements in rain exposed Norway spruce (Picea abies (L.) Karst.) joints

Maria Fredriksson, Lars Wadsö, Peter Johansson, Thomas Ulvcrona

Research output: Contribution to journalArticlepeer-review


In order to perform service life predictions of rain exposed wood structures, the moisture and temperature conditions in the structure need to be known as well as which degradation that occurs under those exposure conditions. The microclimate (the moisture conditions at the surface) is the boundary condition for moisture transport into the wood and depends on the detail design; joints between two pieces of wood can act as a water trap which give long durations of surface moisture after rain events and hinders drying. This study presents moisture content and microclimate measurements in three types of Norway spruce joints exposed to artificial rain in the laboratory. Both the microclimate (the duration of water on surfaces and in gaps) and the moisture content profiles were monitored. The microclimate was changed by changing the size of the gap between the two boards. The duration of water in the gap depended both on the gap size and on the permeability of the wood (sapwood/heartwood, end grain surface/side grain surface). In many cases, a larger gap width gave shorter durations of high moisture contents since a larger gap gave more favourable drying conditions, but the magnitude of this reduction varied between joint types.
Original languageEnglish
Pages (from-to)189-200
JournalWood Material Science & Engineering
Issue number4
Publication statusPublished - 2016 Aug 7

Subject classification (UKÄ)

  • Materials Engineering

Free keywords

  • durability
  • detail design
  • surface moisture
  • moisture content
  • heartwood
  • growth ring width


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