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Where vertical walls project above a roof to permit storm water to drain into the roof area below, the adjacent roof area shall be permitted to be computed from Table 1103.1 as follows:
  1. For one wall — add 50 percent of the wall area to the roof area figures.
  2. For two adjacent walls of equal height — add 35 percent of the total wall areas.
  3. For two adjacent walls of unequal height — add 35 percent of the total common height and add 50 percent of the remaining height of the highest wall.
  4. Two opposite walls of same height — add no additional area.
  5. Two opposite walls of differing heights — add 50 percent of the wall area above the top of the lower wall.
  6. Walls on three sides — add 50 percent of the area of the inner wall below the top of the lowest wall, plus an allowance for the area of the wall above the top of the lowest wall, in accordance with Section 1103.4(3) and Section 1103.4(5) above.
  7. Walls on four sides — no allowance for wall areas below the top of the lowest wall — add for areas above the top of the lowest wall in accordance with Section 1103.4(1), Section 1103.4(3), Section 1103.4(5), and Section 1103.4(6) above.

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