Sprinkler Obstruction Calculator

One of the most common and basic issues in fire sprinkler design or on-site review is whether a sprinkler is considered obstructed. While the premise of the NFPA 13 obstruction tables is fairly straightforward, there are variations that depend on the edition of 13, the sprinkler type, and in some cases the orientation of the sprinkler.

This tool quickly determines whether a ceiling-mounted element is an obstruction — helpful during layout or site review where lugging the entire code volume isn’t practical.

Common examples include sprinklers adjacent to surface-mounted lights, soffits (not against a wall), mechanical equipment in walk-in coolers and freezers, signage, banners, lowered ceilings, thresholds above large openings, raised ceiling pockets, or exit lighting.

Download the full illustrated guide for variable definitions, sample charts, and obstruction evaluation examples.

Horizontal Distance “A”: Edge of obstruction to sprinkler centerline (plan view).

Vertical Distance “B”: Bottom of obstruction to sprinkler deflector elevation (positive downward).

Sprinkler Type: Determines which NFPA table/limits apply.

Edition: NFPA 13 year; sections differ by edition.

Units: US (in/ft) or SI (mm). DXF and PNG exports honor your selection.

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