If an obstruction area measures 20 ft², is this permitted?

If an obstruction area measures 20 ft², is this permitted?

• A. Yes, 20 ft² is allowed if spacing is correct.
• B. Yes, if there are multiple sprinklers.
• C. No, must not exceed 18 ft².
• D. It depends on floor area.

Answer: (C)

In NFPA 13R, each sprinkler head has a maximum allowable obstruction area on the floor around it that it must be able to cover effectively. That limit is 18 square feet per head. If the obstruction area measures 20 ft², it exceeds the allowed maximum, so this configuration isn’t permitted because the sprinkler wouldn’t reliably distribute water to the protected space behind the obstruction. To comply, you’d need to reduce the obstruction area to 18 ft² or less, perhaps by repositioning the obstruction or adding an additional sprinkler so that no single head has to cover more than 18 ft² of obstructed area.

In NFPA 13R, each sprinkler head has a maximum allowable obstruction area on the floor around it that it must be able to cover effectively. That limit is 18 square feet per head. If the obstruction area measures 20 ft², it exceeds the allowed maximum, so this configuration isn’t permitted because the sprinkler wouldn’t reliably distribute water to the protected space behind the obstruction. To comply, you’d need to reduce the obstruction area to 18 ft² or less, perhaps by repositioning the obstruction or adding an additional sprinkler so that no single head has to cover more than 18 ft² of obstructed area.