Also in: Disaster Response and Recovery
Trapped Ceiling-Cavity Water Load and Collapse Screen
The distributed load (a foot of water is 62.4 psf), total weight.
Example
You enter
- Bulging / saturated ceiling area (ft²) 20
- Average trapped water depth (in) 2
- Drain-first screen load (psf, editable) 5
You get
- Distributed load 10.4 lb/ft^2
- Total trapped weight 208 lb
Checked against published worked examples from: NDSU Dickinson Research Extension Center (Llewellyn L. Manske).
Details, formula, and sources
ScopeThe distributed load (a foot of water is 62.4 psf), total weight, and volume of water trapped overhead in a sagging ceiling cavity, with a drain-before-entry screen. The threshold is an editable screen value, not a code capacity - the fastening, span, and a structural engineer govern; this decides whether to punch-drain from a safe distance before anyone works beneath the bulge.
Formula or tableload_psf = (avg_depth_in/12) x 62.4; weight_lb = pooled_area_ft2 x (avg_depth_in/12) x 62.4 = volume_gal x 8.34; volume_gal = pooled_area_ft2 x (avg_depth_in/12) x 7.48052; drain_first = load_psf > threshold_psf.
Source and editionHydrostatic load and water density (62.4 lb/ft^3, 8.34 lb/gal, 7.48052 gal/ft^3) by name; ANSI/IICRC S500 safety practice. Not edition-bound.
Free accessWater is ~62.4 lb/ft^3, so a foot of depth is 62.4 psf and an inch is 5.2 psf. The densities are public constants.
What governsEstimate. AHJ and licensed professional govern.
API field namespooled_area_ft2, avg_depth_in, threshold_psf, load_psf, water_weight_lb
- Water density ~62.4 lb/ft^3, 8.34 lb/gal, 7.48052 gal/ft^3pure-math.js convention
- Threshold the drain-first load (default 5 psf) is an editable, conservative screen, not a structural ratingANSI/IICRC S500 safety practice
- Scope a safety screen for trapped overhead water; the wet gypsum's fastening and a structural engineer govern collapseANSI/IICRC S500