To limit the probability that heat from normal operation or from a fire in chimneys, flue pipes or appliances will lead to ignition of nearby combustible material, which could lead to a fire or to the spread of fire to other parts of the building, which could lead to harm to persons.
To limit the probability that close proximity of combustible material to ash pit or cleanout doors will lead to ignition of the combustible material, which could lead to a fire or to the spread of fire to other parts of the building, which could lead to harm to persons.