Starting with version 8.11 of the program, instead of the expressions for external pressure coefficient, C_p, based on height to depth ratio from NBC 2010 Figure I-15 , the program always used the value of 0.27 in the range 0.25 < H/D < 1.0, resulting in loading that was less than half of what it should be. This has been corrected and the program uses 0.27( H/D + 2.0) for windward walls and -0.27( H/D + 0.88) for leeward walls.

Note that for buildings in these ranges are ordinarily designed using the low-rise method, I-7, but Shearwalls does not use this method for multi-block structures, and it is likely not be used for flat roofs, so this problem is likely to have occurred for these types of structures.