Minimum depth and maximum diameter for granular material beneath floors supported on ground or on granular fill, in buildings to which Part 9 applies [see Sentence 1.3.3.3.(1) of Division A for application of Part 9].

Exceptions: 

To limit the probability of an inadequate drainage layer or insufficient capillary break beneath floors-on-ground.

This to limit the probability of:

• the ingress of moisture from the ground, or
• the compromised thermal performance of components intended to provide resistance to heat transfer.

This is to limit the probability of:

• an inadequate control of temperatures in interior spaces, relative humidity, or water accumulation,
• the generation of pollutants from biological growth or from materials that become unstable on wetting, or
• deterioration, which could lead to compromised integrity of elements protected by floors-on-ground.

This is to limit the probability of:

• negative effects on the air quality of indoor spaces,
• the inadequate thermal comfort of persons, and
• contact with moisture.

This is to limit the probability of harm to persons.

To limit the probability that soil gas under floors-on-ground will not reach extraction locations, which could lead to infiltration of soil gas, particularly radon, except in buildings of industrial occupancy where the nature of processes contained therein permits or requires the year-round use of large openings in the building envelope, or in buildings constructed in areas where it can be demonstrated that soil gas does not constitute a hazard.

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