Interpretation #9516

Table 6.4.1.1 of NFPA 58 provides separation distances for both aboveground and underground LP containers. It covers distances between containers, important buildings, and property lines. “Important building” is defined as a building that is considered "not expendable in an exposure fire." This is determined by such criteria as replacement value, human occupancy, value of the contents, effect on firefighting activities, and the effect of a building fire on the tank. If any of these conditions apply, the building is deemed “important” and would trigger the separation distances of NFPA 58 and this table.
The term “important building” appears throughout Section 6.4 (Container Separation Distances.) For example, Section 6.4.1.1. (Aboveground Containers), Table 6.4.1.1 (Separation Distances), and Section 6.4.2.1 (Underground Containers), all refer to “important buildings.” And although Section 6.4.2.3 does use the term “building”, this instance can be inferred to mean “important building” in the overall context of the code.
NFPA 58 container separation distances are not intended to apply to expendable ancillary buildings or structures that do not qualify as an “important building.”