4.3. Safety Factors

Try these first

1. 1.

   Define imposed loads in the context of roofing systems.

   Hint

   Think about what activities occur on roofs.

2. 2.

   What is the typical imposed load range for flat roofs?

   Hint

   Refer to the building codes.

3. 3.

   What is the imposed load range for sloping roofs?

   • 0.5 - 1.0 kN/m²
   • 0.75 - 1.5 kN/m²
   • 1.0 - 2.0 kN/m²

   Hint

   Think about the lighter load implications for design.

4. 4.

   True or False: Wind actions are considered only on the windward side of roofs.

   • True
   • False

   Hint

   Remember how wind interacts with different surfaces.

5. 5.

   Calculate the total imposed load on a flat roof if it is used for a small gathering with an expected occupancy of 80 people, each weighing 75 kg, plus maintenance equipment weighing 500 kg. Assume the area is 100 m².

   Hint

   First, convert the total weight into kN by dividing by gravity.

6. 6.

   A sloping roof with a slope of 30 degrees experiences wind uplift. If the area of the roof is 150 m² and the wind speed is 20 m/s, calculate the wind load using a standard wind load coefficient.

   Hint

   Check the wind load coefficient in your reference materials.