There are two points of view for the prevention design of moisture problem in the building insulated envelope. One is the strictly prevention of high moisture condition in the insulated wall cavity. The other one is the permission of short-term high moisture condition, condensation and high moisture content of the wooden material as long as keeping physical durability. If the later standpoint were chosen, the insulated envelope design of every variety for Japan would be possible. Nevertheless, there are no criteria to estimate the damage of physical durability of wood by the biological factors related high moisture condition.
The points of this paper are as follows;
1) The importance of estimation damage of woods by the moisture problems is describes.
2) 2 case of hygrothermal steady state experiments were done to get basic acknowledge of woods damage by biological factors considering term, water content, temperature and humidity, physical durability.