Talkin’ winter weather as it relates to the building code
Happy New Year
What a great Christmas and New Year break! After what seemed to be a very long fall, the weather finally turned very much like winter.
Trees are covered and quite burdened with the weight of all the snow. It’s amazing that more trees haven’t come down.
It’s equally amazing that the power hasn’t been interrupted more than it has.
But it’s good to see the snow, kind-of forgotten what it liked like!
Since this article is about ‘talking codes’ and not about ‘talking weather’ let’s get back on track.
The obvious topic to mention with all the new snow on the ground, is all the snow on the roof.
Even though the building code requires anywhere from 94 pounds to 110 pounds per square foot design capability for roof systems, is that enough?
Based on the NYS Codes, here is Section 1608.2 Ground snow loads, straight from the code books:
The ground snow loads to be used in determining the design snow loads for roofs shall be determined in accordance with ASCE 7 or Figure 1608.2.
When using Figure 1608.2 for sites at elevations above 1,000 feet (304 m), the ground snow load shall be increased from the mapped value by 2 psf (0.095 kN/m2) for every 100 feet (30 480 mm) above 1,000 feet (304 m).
Site-specific case studies may be made in lieu of snow loads in Figure 1608.2 or ASCE 7.
Ground snow load determination for site-specific case studies shall be approved and shall be based on an extreme value statistical analysis of data available in the vicinity of the site using a value with a 2-percent annual probability of being exceeded (50-year mean recurrence interval. Continue reading →