How far does a propane tank have to be from the house?

An above-ground propane tank of 125 to 500 gal must be 10 ft (3 m) from the house. A tank of 501 to 2,000 gal must be 25 ft (7.6 m) away, or 10 ft if it is the only tank over 125 gal within 25 ft and holds no more than 1,200 gal. An underground tank keeps every part of itself 10 ft away. Below 125 gal there is no distance from the building. Instead, the valves have to stay clear of windows, vents and anything that can light the gas. Each distance applies to the line of the next lot too. The figures come from the International Fire Code (IFC), which follows the national propane code, NFPA 58. The rest of the yard is in outdoor room dimensions.

What a propane tank is, and how its size is counted#

Propane is a fuel gas, also called LP-gas, short for liquefied petroleum gas. It is kept under pressure as a liquid. When it escapes, it turns back into gas: "a gallon of liquid expands to about 270 gallons of gas," in the Minnesota State Fire Marshal's words. The gas "is heavier than air so it tends to seek lower levels." That one fact explains most of the rules below.

The code sorts containers into two kinds.

• A cylinder is a portable container built to US Department of Transportation (DOT) rules. The 20 lb grill bottle and the 100 lb cylinder are both cylinders. Minnesota says they "generally have a nominal maximum capacity of 100 gallons of water."
• A tank is a fixed container built to the ASME pressure vessel code. ASME is the American Society of Mechanical Engineers. Minnesota says tanks "generally have a water capacity (WC) exceeding 100 gallons."

Size is counted in water gallons: how much water the container would hold filled to the brim. Propane is never filled that full. The code caps filling at the tank's fixed gauge or the percentage marked on it (IFC 6106.2). So "a 500 gallon tank" holds less than 500 gal of propane, and the table is read by the water figure on the tank's plate.

Three parts of the tank set the smaller distances:

• The relief valve lets gas out if the pressure inside gets too high, as it can in a fire. North Carolina's LP-gas regulator notes that cylinders relieve at 375 psi and ASME tanks at 250 psi.
• The filling connection is where the delivery driver attaches the hose.
• The liquid-level gauge vent is the small vent on the gauge the driver uses while filling.

Two more terms come from the code's own words. A lot line of adjoining property that can be built on is the boundary with a neighbour's lot that could take a building. A public way is a street or sidewalk.

10 ft, then 25 ft: the table by tank size#

IFC section 6104.3 says containers "shall be located with respect to buildings and lot lines of adjoining property that can be built on, in accordance with Table 6104.3." The table sets one figure for both. These are its rows up to 2,000 gal.

A mounded tank is partly buried and covered with earth or sand. It takes the underground column.

The 1,200 gal exception is footnote f. It reads: "This distance is allowed to be reduced to not less than 10 feet for a single LP-gas container of 1,200-gallon water capacity or less, provided that such container is not less than 25 feet from other LP-gas containers of more than 125-gallon water capacity." Minnesota's table words it as a single tank with "no other LP Gas tanks within 25 ft." That is a little broader than the code. The code only counts other tanks over 125 gal. A 100 lb cylinder for the grill does not cancel the exception.

Footnote g adds the street. An above-ground tank of 2,000 gal or less must be at least 5 ft (1.5 m) from a public way.

Section 6107.3 adds one more ring. "Weeds, grass, brush, trash and other combustible materials" must be kept at least 10 ft (3 m) from the tank.

Under 125 gal: no building distance, but 3, 5 and 10 ft from the valves#

A cylinder or small tank beside the house may run a grill, a patio heater or a standby generator. Footnote e lets containers "of less than a 125-gallon water capacity" stand "without a separation distance". That holds only if three conditions are met. Each one is measured from a part of the container, not from its side.

1. Relief valve to openings below it. For a DOT cylinder, the valve's discharge must be "not less than 3 feet horizontally from building openings below the level of such discharge." For an ASME tank under 125 gal, the figure is 5 ft (1.5 m).
2. Relief valve to ignition and air intakes. The discharge must be at least 5 ft (1.5 m) from "exterior sources of ignition, openings into direct-vent (sealed combustion system) appliances or mechanical ventilation air intakes." A direct-vent appliance is one that draws its combustion air through its own pipe in the wall, such as many furnaces and water heaters.
3. Filling point to ignition and air intakes. If the container is "filled at the point of installation", its filling connection and gauge vent must be at least 10 ft (3 m) from the same three things. A cylinder swapped at a shop is not filled where it stands. One topped up by a delivery truck is.

The first rule is easy to misread. It covers openings below the valve, and it is measured sideways. A window whose sill sits above the valve is outside it. A basement window, a crawl space vent or a low dryer vent beside the cylinder is inside it. Propane sinks, so the low opening is the risk. A dryer vent's own clearances are in dryer venting dimensions and clearances.

Under the house. A DOT cylinder "shall not be beneath buildings unless the space is well ventilated to the outside and is not enclosed for more than 50 percent of its perimeter." An ASME tank under 125 gal must not let its relief valve discharge "in or beneath buildings".

Several small tanks. If containers each under 125 gal add up to 500 gal or more at one site, the table applies to the total. Each such group must also be 25 ft (7.6 m) from the next.

What counts as a source of ignition is not listed in the code. North Carolina's LP-gas regulator has ruled on one common case. It does not treat an electric meter "within the weather seal housing" as one. Nor does it treat a closed breaker box as one, while no one is working on it. But a power interrupter device beside the meter "is considered a source of ignition." And "a propane container within ten feet of either device may not be filled" while it is being worked on or if the meter seal is broken.

Underground tanks: 10 ft from every part#

An underground tank of up to 2,000 gal is 10 ft (3 m) from the house in the table, whatever its size. Footnote a explains how that is measured. The distance runs "from the pressure relief device and the filling or liquid-level gauge vent connection". But it adds that "all parts of an underground LP-gas container shall be not less than 10 feet from a building or lot line". So the 10 ft runs to the nearest point of the buried tank, not to the lid you see on the lawn.

North Carolina's LP-gas regulator explains the purpose. The gap lets "any gas that escapes from a leak in the tank or piping to find its way to the surface and disperse before it enters a house." That reason leads to one exception, common on its coast and in its mountains. Where a house stands on piles with clear air under it and "no skirting around the piles", North Carolina allows the tank "up to the footprint of the building". "No part of the tank may be underneath the footprint," which it ties to NFPA 58 section 6.4.2.3. Any enclosed part of the building that touches the ground still needs the full 10 ft. If a deck or overhang on that side is less than 10 ft wide, the tank goes out far enough "to make up the 10 feet".

Not under a porch roof: the overhang rule#

The Texas Railroad Commission's builder checklist states the rule in one line: "Tanks may not be covered by porches, patio overhangs, awnings, etc." Its drawings follow the 2001 edition of NFPA 58, so its clause numbers are out of date. The current IFC still keeps a tank out from under the house.

The IFC puts a number on it in footnote b, for ASME tanks of 125 gal or more. Any part of the building that projects "more than 5 feet from the building wall" and is "higher than the relief valve discharge outlet" gets half the table distance. That half is measured "from a point determined by projecting the outside edge of such overhanging structure vertically downward to grade." The full distance to the wall still applies too.

So for a 500 gal tank:

• A 24 in (61 cm) eave projects less than 5 ft. The rule does not apply. The tank is 10 ft from the wall and well clear of the eave anyway.
• A 12 ft (3.66 m) covered patio projects more than 5 ft. The tank must be 5 ft from the edge of its roof, measured on the ground.

The rule falls away only where the overhang is "50 feet or more above the relief-valve discharge outlet".

The same thinking runs through the grill manuals, which forbid a grill under a combustible roof, as set out in how far a grill should be from the house.

Worked through: one 500 gal tank behind a house#

Take a house with a covered patio at the back. The patio roof is 14 ft (4.27 m) wide, projects 12 ft (3.66 m) from the wall, and sits well above a tank's relief valve. The rear lot line runs 24 ft (7.32 m) behind the wall. The plan is a 500 gal above-ground tank, filled in place by a delivery truck. Suppose it is about 3 ft (0.9 m) across. Walk it through the rules.

1. The wall. The table puts a 500 gal tank 10 ft (3 m) from the building.
2. The patio roof. It projects more than 5 ft, so footnote b applies. Half of 10 ft is 5 ft (1.5 m) from the roof's edge, measured on the ground. In front of the patio, that puts the tank 12 + 5 = 17 ft (5.18 m) from the wall.
3. Beside the patio instead. Move the tank to the side of the roof. Now it needs 10 ft from the wall and 5 ft from the roof's side edge. It sits 7 ft (2.13 m) closer to the house than in front.
4. The lot line. The tank needs 10 ft from the rear line too. Its far side sits 10 + 3 = 13 ft from the wall. That leaves 24 - 13 = 11 ft (3.35 m) to the line. It passes, by 1 ft.
5. The grill. A gas grill is an open flame. By the wording of footnote e, it must stand 10 ft from the tank's filling connection, because the tank is filled where it stands.
6. The ground. Keep a 10 ft ring around the tank clear of brush, long grass and the log pile.

The property line counts as much as the house#

The table measures to buildings and to "lot lines of adjoining property that can be built on". Both get the same figure. Minnesota's table shows them side by side: 10 ft to buildings and 10 ft to property lines for 125 to 500 gal, and 25 ft to both for 501 to 2,000 gal. For tanks under 125 gal it gives 0 to both.

North Carolina explains why the line matters. It keeps "the tank at least 10 feet from whatever building might be on the other side of the property line." The neighbour's empty side yard could hold a house next year. Your tank has to be placed as if it already does.

On a narrow lot this decides the spot. A side yard 15 ft (4.57 m) wide cannot hold a 500 gal tank between the house and the fence. It needs 10 ft from each, plus its own width. The tank goes to the back garden instead, or the house uses cylinders under 125 gal, which need no distance from either beyond the valve rules. A fence may stand inside the true line, so check the survey. Fence heights and permits are covered in fence height without a permit.

Other buildings on your own lot count too. The IFC table says "buildings". NFPA 58 uses the phrase "important building", defined in section 3.3.38 as "A building that is considered not expendable in an exposure fire". North Carolina reads that widely. A building counts if people use it, if it is combustible or holds combustible material, or if it holds a source of ignition. It also counts "if a building is locked or it or its contents are insured". On that reading, a locked garden shed of the size in how big a shed can be without a permit takes the same 10 ft as the house.

Which distance applies#

This table restates the rulings above. Each row points to the source behind it.

Where these figures stop applying#

The figures here are the 2021 IFC as Colorado adopted it, with NFPA 58 as the Minnesota State Fire Marshal quotes it. Every state and city adopts its own editions, and some amend them. In Texas and North Carolina, a state agency also regulates LP-gas: the Railroad Commission and the Department of Agriculture. Your propane supplier sets the tank and must meet your local rules. Where the supplier or the inspector asks for more, that governs.

Two points in the code are less settled than they look. In the IFC table, footnote e is attached to the rows for tanks under 125 gal and for 501 to 2,000 gal. Its 10 ft filling-point rule is worded for any container "filled at the point of installation", but ask how your area applies it to a 250 or 500 gal tank. And the code does not list what counts as a source of ignition. Whether an air-conditioning condenser, a pool pump or a hot tub's equipment pack counts is for your supplier or inspector to say. The North Carolina rulings quoted here bind only in North Carolina.

This page covers where a tank or cylinder stands. It does not cover the gas piping, the regulator, the tank pad or protection from cars, which the IFC leaves to NFPA 58. It does not cover large tanks over 2,000 gal or commercial sites. It does not cover cylinders used indoors. The code bars them from a basement or similar low space unless it has approved ventilation (IFC 6103.2.1.1).

The appliance on the end of the line keeps its own clearances. A standby generator on propane is placed by its own rules, in how far a generator should be from the house. An outdoor kitchen's cylinder compartment is sized in outdoor kitchen dimensions, and a fire pit's code distances are in fire pit clearances. Metric figures are conversions, except the code's own 7,570 L, as imperial and metric dimension systems explains; check your own with the unit converter. Terms such as combustible are defined with others in the glossary, and the codes this site uses are listed under standards and codes.