Technical Booklet D Structure·Page 56·4B.15
Purlin design loads and installation requirements
Purlins must be installed normal to the roof pitch to resist only the perpendicular load component; designers must ensure the roof construction accommodates the parallel load component. Notching or drilling of purlins is prohibited unless justified by specialist calculation.
The tabulated purlin sizes are designed to resist only the load component perpendicular to the roof pitch with purlins installed normal to the roof pitch. Designers should ensure that the roof construction can satisfactorily accommodate the component of load parallel to the roof pitch.
Notching or drilling of the purlins should not be carried out unless justified by specialist calculation.
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