Tool

Soffit Sprinkler Placement

Enter the width and height of the soffit to find required sprinkler placement. Supports NFPA 13-2019 Chapter 10 standard spray and Chapter 12 residential sprinklers — pendent, upright, and sidewall orientations.

Soffit Sprinkler Placement

Find required sprinkler placement for soffits and obstructions against the wall, per NFPA 13-2019 Chapter 10 (standard spray) and Chapter 12 (residential).

Sprinkler type

Sprinkler standard

Orientation

Uses the obstruction-against-wall formula: A = D − 8″ + B.

Soffit dimensions

Width (D)

Horizontal projection of the soffit from the wall. The formula applies only up to 30″; past that, position it under the general obstruction rules. Sprinklers are required beneath the soffit once it exceeds 4 ft (NFPA 13-2019 10.2.7.3.2).

Soffit below deflector (B)

Vertical distance from the sprinkler deflector down to the bottom of the obstruction, per NFPA 13-2019 Fig. 10.2.7.1.2(b). The soffit hangs below the deflector by B. Soffits deeper than 24″ should be checked against beam rules.

Section view

Obstruction against wall

D — soffit projection from wallB — soffit below deflectorA — required distance from wall

A is measured from the face of the wall, not from the edge of the soffit. At A = 20″ the sprinkler is still 4″ inside the soffit's 24″ projection — see the notes below.

Engineering disclaimer

Results are for preliminary engineering only. Final designs must be reviewed by a licensed fire protection engineer and verified against NFPA 13/14 and the local AHJ.

Minimum distance from wall to sprinkler

1' 8"

Place the sprinkler at least 1' 8" from the wall.

NFPA 13-2019 Figure 10.2.7.1.2(b)

Calculation

Formula: A = D − 8″ + B
Soffit width (D): 24″
Soffit below deflector (B): 4″
Computation: 24″ + 4″ − 8″ = 20″
Required A: 20″

Inputs

Sprinkler standard: Standard spray (NFPA 13 Ch. 10)
Orientation: Pendent / upright
Soffit width (D): 2'
Soffit below deflector (B): 4"
Method: Formula
Reference: NFPA 13-2019 Figure 10.2.7.1.2(b)

Notes

NFPA 13-2019 Figure 10.2.7.1.2(c) allows an obstruction against the wall up to 24″ wide with no additional protection beneath it, and with no limit on how far it hangs down, where the sprinkler is within ½ S of the wall. Check the sprinkler's spacing before relying on it.
Required distance A is less than the soffit width D, so a sprinkler placed at the minimum A would fall under the soffit rather than hang from the open ceiling. Verify placement against the under-soffit sprinkler rules for this soffit width.