Obstruction Height refers to the height of obstruction affecting sprinkler placement.

• A. Height of ceiling
• B. Height of obstruction affecting sprinkler placement
• C. Height of sprinkler head
• D. Height of room

Answer: (B)

Obstruction height is about the tall objects in a space that can block or alter the water spray from a sprinkler. In residential sprinkler design, anything within the sprinkler’s discharge pattern—like cabinets, beams, bulkheads, or other fixtures—has to be considered, and the vertical size of that object from the finished floor up to its top is the obstruction height. This height matters because a taller obstruction intrudes more into the spray path and can reduce coverage or require adjustments to sprinkler placement, head type, or spacing to ensure the protected area still receives adequate water. The other options describe different dimensions of the room or the head itself, which don’t define obstruction height.