Skip to main content

---

Example 2.3: Find snow loads

Jonathan Ochshorn

© 2009 Jonathan Ochshorn.

contact | academic homepage | Structural Elements for Architects and Builders | calculator homepage

---

Directions: Enter values for ground snow load, exposure, terrain, thermal factor, importance, roof type and slope, and surface characteristics (i.e., slippery or nonslippery surface). Typical roof types are illustrated in Fig. 1 below, with the distance, W, measured from eave to ridge in gable- or hip-type roofs.

Note that this calculates only the basic roof snow load, and does not account for unbalanced loads (where wind may blow snow from one side of the roof to another), or take other aspects of roof geometry into account (for example, surcharges due to drifting snow that could accumulate against walls, parapets, or other obstructions).

Press "update" button.

More detailed explanations and examples can be found in my text.

	""
		exposure	terrain
Boston, MA: 35 psf Chicago, IL: 25 psf Little Rock, AR: 5 psf Houston, TX: 0 psf Ithaca, NY: 35 psf Los Angeles, CA: 0 psf Miami, FL: 0 psf New York, NY: 30 psf Philadelphia, PA: 25 psf Phoenix, AZ: 0 psf Portland, ME: 50 psf Other (specify at right):		full exposure partial exposure sheltered	B: urban/suburban C: open terrain D: flat unobstructed windswept mountain Alaska-no trees	normal: 1.0 cold, vented with R>25: 1.1 unheated structure: 1.2 heated greenhouse with R<2: 0.85	I=low hazard: 0.8 II=normal: 1.0 III=high hazard: 1.1 IV=essential: 1.2
roof type				roof surface	roof snow load
hip or gable mono-slope or flat		1:12 = 4.76 deg 2:12 = 9.46 deg 3:12 = 14.04 deg 4:12 = 18.43 deg 5:12 = 22.62 deg 6:12 = 26.57 deg 7:12 = 30.26 deg 8:12 = 33.69 deg 9:12 = 36.87 deg 10:12 = 39.81 deg 11:12 = 42.51 deg 12:12 = 45.00 deg <= 5 degrees other (degrees)		slippery non-slippery
""		""			""
Checks:
errors:
exposure n/a
W>0
angle >0 and < 90
ground snow load > 0

---

Disclaimer: This calculator is not intended to be used for the design of actual structures, but only for schematic (preliminary) understanding of structural design principles. For the design of an actual structure, a competent professional should be consulted.

First posted July 12, 2009 | Last updated July 12, 2009