急求FDS高手啊！！！！

aikcn

&MATL ID = 'BRICK'
  CONDUCTIVITY = 0.69
  SPECIFIC_HEAT = 0.84
  DENSITY = 1600. /
&SURF ID = 'BRICK WALL'
  MATL_ID = 'BRICK'
  COLOR = 'RED'
  BACKING = 'EXPOSED'
  THICKNESS = 0.20 /
&OBST XB=1.0, 5.0, 1.0, 2.0, 0.0, 1.0, SURF_ID='BRICK WALL' /


OBST定义的障碍物最小尺寸是1m，而SURF中THICKNESS定义的材料层的厚度是0.2m，那这个实际材料层在障碍物上是怎么分布的？是四周各0.2中间空心还是什么样的？求解啊！