Atas Smarts #4 - FM Global Wind Uplift Ratings

The letters "FM" stand for Factory Mutual.

FM, or Factory Mutual, conducts their own testing and writes their own standards. This means that they have their own engineers who are responsible for testing products and ensuring that they meet FM's standards. This allows FM to have control over the testing process and ensures that their standards are followed.

The field area of the roof is less susceptible to wind uplift damage because it is located in the middle of the roof and is not directly exposed to the edges or corners where wind forces are typically stronger. The corners and perimeter of the roof are more vulnerable to wind uplift as the wind can create a lifting force on these areas. The ridge of the roof may also be susceptible to wind uplift, depending on its design and construction.

FM is an insurance company because it is not mentioned as a governing code body, roofing industry association, or an independent product testing facility. The fact that FM is an insurance company is implied by the options given.

The correct answer is FM 1-150 for the perimeter and FM 1-225 for the corners. This means that for an FM 1-90 rating, the perimeter of the system must meet the specifications outlined in FM 1-150, while the corners of the system must meet the specifications outlined in FM 1-225.

FM 1-90 is considered the default standard for roofing systems that are NOT located on a coastal or high wind area.

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24 Gauge Steel is not considered an FM approved roof deck because FM Global, a global insurance company, has specific requirements and standards for roof decks to be considered FM approved. These requirements include fire resistance, wind uplift resistance, and structural integrity. While 24 Gauge Steel may be a common material for roof decks, it may not meet FM Global's specific standards and therefore is not considered FM approved.

FM Global recommends a minimum "Importance Factor" of 1.15 for all roof designs. This means that FM Global considers the roof to be relatively important in terms of protecting the building and its contents from damage. The higher the importance factor, the more stringent the design and construction requirements are for the roof. A lower importance factor would indicate that the roof is considered less critical in terms of its impact on the overall safety and protection of the building.

FM Global recommends a minimum "Safety Factor" of 3.0 for roof designs of a "special use facility" (such as a hospital or nursing home). This means that the design of the roof should be able to withstand three times the maximum expected load or stress that it may experience. This higher safety factor ensures that the roof can handle any potential additional loads or stresses that may occur due to various factors such as extreme weather conditions or equipment installations on the roof. This helps to ensure the safety and structural integrity of the roof in a special use facility where the consequences of roof failure could be severe.

The correct answer is Class 1 interior fire classification and 45 lbs psf of actual field of roof wind uplift pressure. This means that the wind uplift classification rating of 1-90 represents a Class 1 interior fire classification and a wind uplift pressure of 45 lbs per square foot on the actual field of the roof.