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DynoRaxx Evolution PR Guide to Code Compliant Installation

14 | P a g e 8 6 6 . 6 2 0 . 2 4 1 0 | d y n o r a x x . c o m

B. Snow Loading Calculation Procedure

This section is concerned with the effects of snow loading on a particular fixed structure. On sloped roofs, the

snow load is:





 







Where:





represents the sloped roof snow load





is the roof slope factor





is the flat roof snow load

Hence, in order to calculate the sloped roof snow load, one must find the corresponding flat roof snow load,

and multiply that value with the appropriate coefficients. The methodology that will be used is outlined in

chapter 7 of the ASCE 7-05. Please refer to this book for further information.

Task 1: Calculate the ground snow load, 



. The ground snow load should be based upon the extreme values

in the vicinity of the installation site. These values are shown on the map in pages 15-16. Select the value that

corresponds to the installation site. If the site is located in an area that is represented by a “CS,” it means that

the snow fall is highly variable. In this scenario, consult a local professional for the ground snow load.

Task 2: Determine the Exposure Factor, 



. These values may be determined from the table below, which

lists the values for a fully and partially exposed roof. A fully exposed roof is defined to be a roof that is

exposed on all sides with no shelter provided by terrain, trees, or other higher structures. Partially exposed

roofs are roofs that have some form of shelter as afforded by the environment. For information on the

Exposure Category, please refer back to pages 4-5 for specific descriptions.

Adapted from table 7-2, p. 92 of the ASCE 7-05

Task 3: Determine the Thermal Factor, 



. This variable describes the thermal condition of the structure, and

in most cases is 1. However in special cases the value of this coefficient may change, and is described in the

table below:

Thermal Condition





All structures except those below

1.0

Structures kept just above freezing

1.1

Unheated structures kept below freezing

1.2

Continuously heated greenhouses

0.85

Adapted from Table 7-3, p. 93 of the ASCE 7-05

Exposure