1.4.4
Roof Snow Loads
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NOTE: Snow load, including unbalanced roof snow
loads and drift load will be calculated in
accordance with ASCE 7.
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The design roof snow loads shall be as shown on the contract drawings.
1.4.5
Wind Loads
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NOTE: The internal pressure coefficient for
buildings shall be in accordance with ASCE 7. The
internal pressures also apply to SSSMR systems above
substrates since the panels do not lay directly on
the substrate.
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The design wind uplift pressure for the roof system shall be as shown on
the contract drawings. The design uplift force for each connection
assembly shall be that pressure given for the area under consideration,
multiplied by the tributary load area of the connection assembly. The
safety factor listed below shall be applied to the design force and
compared against the ultimate capacity. Prying shall be considered when
figuring fastener design loads.
a.
Single fastener in each connection.........3.00
b.
Two or more fasteners in each connection...2.25
1.4.6
Thermal Loads
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NOTE: Select appropriate temperature range based on
effects of direct sun and general climatic
conditions of the project site.
Insulated structures experience greater temperature
differences than that of uninsulated structures.
For specific projects, giving consideration to the
panel color, building location, infrared heating by
the sun, and the cooling effect of the roof
radiating into the night sky, the designer should
use a maximum temperature range of 104 degrees C
(220 degrees F) for an insulated building and a
maximum temperature range of 71 degrees C (160
degrees F) for an uninsulated building to compensate
for the differential movement between the roof
panels and the structural framework.
For wood structures, insulated buildings that are
temperature sensitive, or in extreme climate areas,
a greater temperature range should be considered.
Dark roofs in mountain areas may be subject to a
temperature range of 116 degrees C (240 degrees F)
or more. For lateral expansion the thermal movement
SECTION 07416A
Page 12
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