The heat transfer coefficient values of 0.250 W/mK and l: 0.261 W/mK were found for Type 1 boards (bark based experimental boards of XBI and YBV)and l: 0.321 W/mK and l: 0.311 W/mK were found for Type 2 boards (cone based experimental boards of XCV and YCII), respectively. But all these are lower than standard value of 0.065 W/mK. However, visual evaluation show that all samples have low flame spreading properties which did not reach the threshold limit of 150 mm under a single flame combustion test. All Type 1 boards show lower mass loss (w, %) than control sample (B0: 11.97%), regardless of mineral additive type and proportions. The lowest mass loss of 6.36% was obtained with sample of YBIV. It is noticeable that olivine-cone (YC) and olivine-bark (YB) based panels usually show lower mass loss than dolomite-cone and dolomite-bark based panels at similar experimental conditions. The surface burning tests clearly indicate that the both mineral additions have lowering effects on burning feature of boards. This is probably olivine and dolomite could be absorbing heat and release water. Hence the burning area might become colder during evaporation of water with increasing charring and improve insulation of materials. The heat insulation levels of boards have found to be closely related with mineral content. But olivine seems to more effective for improving insulation properties for Type 1 boards. It is also found that both type panels (Type 1 and 2) which prepared from various proportions of dolomite and olivine as additives (10-50%) were show higher resistance against thermal degradation than control panels which prepared only (100%) from lignocellulosic material (cone and bark)
