Installation Manual
DynoRaxx Evolution PR Guide to Code Compliant Installation
21 | 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
VII. Calculation of Critical Test Load
The purpose of this section is to go through the calculations described in the manual, by applying it to a critical
test load. Here the critical test load signifies the highest stress loads a system may theoretically come to
experience. As for such, we will make the following assumptions in our calculations:
1. The Basic Wind Speed is 130 mph
2. The mean roof height is 60 ft
3. Exposure Category D, hence a value of of 1.87
4. Topographic value of
=1
5. Importance Factor I= 1.0
6. Effective Wind Area A=20 square feet
7. Net Design Wind Pressure
, 12.4 (Down-Force), -76.8 (Uplift)
8. Roofing material 5/8” CDX plywood
With these numbers, the net design pressure
is:
If the area of the solar module A is 20 square feet, we must multiply the net design pressure by 20:
There is a total of 2872 pounds of uplift at the installation site. However, this wind load is distributed to 2
Evolution PRs, each having 5 screws. Hence, this force is effectively distributed between 10 screws at
(2872)/(10) pounds each, or 287.2 pounds/screw. However, because the pullout strength for the CDX roofing
material is 430 pounds (see the previous page), the system will not fail.