At what width soffit must you install a sprinkler above and below a soffit when dealing with horizontal sidewall sprinklers in soffits?

When dealing with horizontal sidewall sprinklers installed in soffits, the requirement for installing additional sprinklers above and below the soffit is specified based on the width of the soffit. In this case, if the soffit width is 8 inches, the code mandates that sprinklers should be installed both above the soffit and below it. This is crucial for ensuring adequate coverage and achieving the necessary fire protection.

The reason 8 inches is the threshold for this requirement is related to the need for effective water distribution by the sprinklers. When soffits are wider, they can potentially obstruct the spray pattern of the horizontal sidewall sprinklers. Therefore, at widths of 8 inches or more, two sprinkler heads (one above and one below) are necessary to maintain a consistent and effective coverage area for fire suppression.

In contrast, wider soffits such as 16 inches and 24 inches would also necessitate the installation of sprinklers per code, but the immediate requirement begins at 8 inches. Thus, this option is the most accurate in relation to the installation guidelines for horizontal sidewall sprinklers in soffits.