Sentence 9.32.3.11.(7)

Intent 1:

To limit the probability that the cross-sectional area of the ductwork will be reduced by crushing, which could lead to a reduced volume of air distribution in the ductwork, which could lead to:

• excessive negative or positive indoor air pressure from an unbalanced system, or
• reduced exhaust capacity, which could lead to inadequate ventilation.

This is to limit the probability of negative effects on the air quality of indoor spaces, which could lead to harm to persons.

Intent 2:

To limit the probability of excessive sagging, movement or vibration, which could lead to:

• the accumulation of condensed water vapour in outdoor air supply ducts, or
• the opening of joints, which could lead to:
  • the leakage of exhaust air and pollutants into living space, or
  • the leakage of water vapour into unheated space.

This is to limit the probability of the generation of pollutants from biological growth, which could lead to negative effects on the air quality of indoor spaces, which could lead to harm to persons.