Reference table by tank size
Setback distances apply equally to buildings and property lines:
- 100 lb cylinder (~23 gal): 5 ft from building openings, 10 ft from cellar windows
- 120 gal ASME: 10 ft from buildings and property lines
- 250 gal ASME: 10 ft from buildings and property lines
- 500 gal ASME: 10 ft from buildings and property lines
- 1,000 gal ASME: 25 ft from buildings and property lines
- Underground (residential range): 10 ft regardless of size
Fill valve and vent setbacks (all sizes)
Regardless of tank size, the fill valve, relief valve discharge, and any vent openings must sit at least 10 ft from any building opening (window, door, vent intake) and 10 ft from any ignition source (AC condenser, electrical panel, light switch on exterior wall).
FAQ
Why is a 1,000 gal tank 25 ft from the house but 500 gal is only 10 ft?
NFPA 58 scales setback distance with the energy stored in the tank. A 1,000-gallon tank holds more than twice the propane of a 500-gallon tank and presents a larger potential hazard in the unlikely event of catastrophic failure — hence the larger required setback.
What if my tank is closer than required?
Many older installations sit closer than current NFPA 58 setbacks would require — they may have been compliant when installed under an earlier code edition. Existing non-compliant installations are usually 'grandfathered' but cannot be moved or modified without bringing them up to current code.