A “shadow area” in sprinkler lingo is the theoretically dry space beyond an obstruction, such as a structural column of soffit, which will not be covered by water discharged from a sprinkler. What to do about these areas is a common question NFPA staff liaison Matt Klaus gets when he teaches courses on NFPA 13, Installation of Sprinkler Systems.
Klaus offers up some advice on how to address these potential issues in his latest “In Compliance” column on NFPA 13 in the July/August issue of NFPA Journal. There is advice given in the code, as well as comprehensive obstruction rules, Klaus writes. NFPA 13D, Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, and NFPA 13R, Installation of Sprinkler Systems in Low-Rise Residential Occupancies, also contain a rule that the cumulative shadow area for each sprinkler must not exceed 15 square feet.
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