Intent 1:
To limit the probability of insufficient vertical
clearance, which could lead to:
- the blockage of intake openings by accumulated snow,
or
- the ingress of dust or grass clippings.
This is to limit the probability of
an inadequate supply of makeup air, which could lead to excessive
negative pressure in dwelling units, which could lead to:
- the ingress of soil gases (such as methane and radon),
- the spillage of combustion products from fuel-burning
appliances that are susceptible to spillage, or
- moisture ingress from the ground, which could lead to
the generation of pollutants from biological growth or from materials
that become unstable on wetting.
This is to limit the probability of negative effects on
the air quality of indoor spaces, which could lead to harm to persons.