Firefighting

PYRAMIDAL ROOFS

Issue 6 and Volume 155.

BY FRANCIS L. BRANNIGAN, SFPE (Fellow) A pyramidal roof support is made up of short light-steel sections in a space frame, a three-dimensional truss. If fire is in the roof, the lightweight steel sections will become distorted. Undesigned torsional forces will be generated in all directions; the effect on the total roof will be unpredictable. You must use the thermal imaging camera if fire is in the roof void unless full sprinkler protection is installed. If sprinklers are out of service and the fire should reach the roof void, abandon interior operations because these conditions are very hazardous for firefighters. When preplanning, consider the following: Is the building sprinklered? Do the sprinklers extend to the roof void? A fire in an unsprinklered roof void will spread rapidly on the plywood or chipboard (oriented strand board). The void space may be used for lightweight storage. The ceiling grid may be suspended…

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