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Moisture and bio-deterioration risk of building materials and structuresL?hdesm?ki

Viitanen, H., Vinha, J., Salminen, K., Ojanen, T., Peuhkuri, R., Paajanen, L. and L?hdesm?ki,
2010
Journal of Building Physics 33 (3), pp. 201-224

Viitanen, H., Vinha, J., Salminen, K., Ojanen, T., Peuhkuri, R., Paajanen, L. and L?hdesm?ki,, (2010), "Moisture and bio-deterioration risk of building materials and structuresL?hdesm?ki", Journal of Building Physics 33 (3), pp. 201-224.
Abstract:
There are several biological processes causing aging and damage to buildings. This is partly due to natural aging of materials and excessive moisture. The demands on durability, energy balance, and health of houses are continually rising. For mold development, the minimum (critical) ambient humidity requirement is shown to be between RH 80% and 95% depending on other factors like ambient temperature, exposure time, and the type and surface conditions of building materials. For decay development, the critical humidity is above RH 95%. Mold typically affects the quality of the adjacent air space with volatile compounds and spores. The next stage of moisture-induced damage, the decay development, forms a serious risk for structural strength depending on moisture content, materials, temperature, and time. The worst decay damage cases in North Europe are found in the floors and lower parts of walls, where water accumulates due to different reasons. Modeling of mold growth and decay development based on humidity, temperature, exposure time, and material will give new tools for the evaluation of durability of different building materials and structures. The models make it possible to evaluate the risk and development of mold growth and to analyze the critical conditions needed for the start of biological growth. The model is also a tool to simulate the progress of mold and decay development under different conditions on the structure surfaces. This requires that the moisture capacity and moisture transport properties in the material and at the surface layer be taken into account in the simulations. In practice there are even more parameters affecting mold growth, e.g., thickness of the material layers combined with the local surface heat and mass transfer coefficients. Therefore, the outcome of the simulations and in situ observations of biological deterioration may not agree. In the present article, results on mold growth in different materials and wall assemblies will be shown and existing models on the risk of mold growth development will be evaluated. One of the results of a newly finished large Finnish research project ¡®modeling of mold growth' is an improved and extended mathematical model for mold growth. This model and more detailed research results will be published in other papers.

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Author Information and Other Publications Notes
Viitanen, H.
VTT Building Technology, Wood Technology, P.O. Box 1806, FIN-02044 VTT, Finland
  1. Factors affecting mould growth on kiln dried wood
  2. Factors affecting the development of mould and decay in wooden material and wooden structures
  3. Modeling mould growth and decay damages
  4. Mould and blue stain on heat treated wood
  5. Mould growth on wood at fluctuating humidity conditions, energy efficiency and energy conservation: policies, programmes and their effectiveness
  6. The response of building materials to the mould exposure at different response conditions
  7. Towards modelling of decay risk of wooden materials
  8. Volatile metabolites of Serpula lacrymans, Coniophora puteana, Poria placenta, Stachybotrys chartarum and Chaetomium globosum  
Vinha, J.
Department of Civil Engineering, Tampere University of Technology, P.O. Box 600, 33101, Tampere, Finland
  1. Drying of timber-framed wall structures
  2. Estonian climate analysis for selecting moisture reference years for hygrothermal calculations
  3. Hygrothermal calculations and laboratory tests on timber-framed wall structures
  4. Indoor humidity loads and moisture production in lightweight timber-frame detached houses
  5. Moisture behavior of timber-framed external wall structures in Nordic climate
  6. Moisture transport in timber-framed external wall structures in Nordic climate - laboratory tests
  7. Principles to analyze the moisture performance of timber-framed external wall assembly due to diffusion
  8. The effects of ventilation systems and building fabric on the stability of indoor temperature and humidity in Finnish detached houses
  9. Water vapour transmission in wall structures due to diffusion and convection  
Salminen, K.
     
Ojanen, T.
Tiiomo Ojanen Senior research scientist VTT Building Technology, Finland.
  1. Drying capabilities of wood frame walls with wood siding
  2. Effect of exfiltration on the hygrothermal behaviour of a residential wall assembly: results from calculations and computer simulations
  3. Heat and mass transfer between indoor air and a permeable and hygroscopic building envelope: part I -- field measurements
  4. Heat and mass transfer between indoor air and a permeable and hygroscopic building envelope: part II --verification and numerical studies
  5. Improving indoor climate and comfort with wooden structures
  6. Improving the drying efficiency of timber frame walls in cold climates, by using exterior insulation
  7. Integration of simplified drying tests and numerical simulation in moisture performance analysis of the building envelope
  8. Measuring and modeling vapor boundary layer growth during transient diffusion heat and moisture transfer in cellulose insulation
  9. Modeling heat, air and moisture transport through building materials and components
  10. Moisture buffer value of building materials
  11. Moisture Buffer Value of Materials in Buildings
  12. Moisture performance of an airtight, vapor-permeable building envelope in a cold climate
  13. Moisture transport coefficient of pine from gamma ray absorption measurements
  14. Numerical simulation of mould growth in timber frame walls
  15. Thermal and moisture performance of a sealed cold-roof system with a vapor-permeable underlay
  16. Towards modelling of decay risk of wooden materials  
Peuhkuri, R.
  1. International building physics toolbox, general report
  2. Investigation of Microclimate by CFD Modeling of Moisture Interactions between Air and Constructions
  3. Moisture buffer value of building materials
  4. Moisture Buffer Value of Materials in Buildings
  5. Moisture dynamics in building envelopes
  6. Non-isothermal water vapour transmission through porous insulation. Part 1: The climate chamber
  7. The International Building Physics Toolbox in Simulink
  8. Towards modelling of decay risk of wooden materials  
Paajanen, L.
     
L?hdesm?ki,
     


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