Critical times, moisture contents and temperatures for detectable strength loss in plywood and oriented strand board : planning and proposed work|IN: Limiting conditions for decay : compilation of reports.
The project objective is to identify the wood-rotting fungi causing decay in Canadian buildings, and to provide data for a numerical model which will provide an indication of the time required for initiation of strength loss in wood-based panels when exposed to a range of moisture contents and temperatures.
The MEWS consortium led by the National Research Council's Institute for Research in Construction is developing a computer model to predict the moisture and temperature conditions within a construction assembly in service. By including a damage function calculation for the various building components, the model can predict the consequences of these conditions in terms of strength loss.
We do not have strength data on North American wood species exposed to decay fungi under limiting conditions (20-30%). There is also no standard protocol for assessing strength loss due to decay in non-ideal conditions. Forintek's role is to develop an experimental protocol that will be universally acceptable in the field of wood science, and generate a data set from which one could derive a damage equation for wood decay as a function of time, temperature and moisture conditions. Discussions have established that strength loss in sheathing is the first priority.
A series of proposed test methods were examined. In consultation with members of the consortium task force, a method was selected which was felt would provide suitable strength loss data within the constraints of the funding available.