To limit the probability that, in a fire situation, molten ammonium nitrate will begin to pool [in a basement, crawl space, floor drain, tunnel, elevator pit or other pocket], which could lead to the spread of fire, which could lead to damage to the building.
To limit the probability that, in a fire situation, molten ammonium nitrate will be trapped in a floor drain or similar space that may contain contaminants, which could lead to a fire or explosion involving the molten ammonium nitrate, which could lead to damage to the building.