How far should a patio heater be from the ceiling and walls?

A standing propane patio heater needs 36 in (91 cm) clear above its top and 24 in (61 cm) clear round its sides, measured to anything that can burn. That is the figure in the Fire Sense manuals, sold by Lowe's, Home Depot and Costco. Other makers print 18 to 48 in (46 to 122 cm) above, so the manual for your model is the one that counts. Add the top clearance to the heater's height and you have the ceiling it needs: 10 ft 5 in (3.18 m) for an 89 in (226 cm) heater. The 3 to 5 ft and the "7 to 8 ft ceiling" that circulate are not in any manual read here. Wall-mounted, electric and tabletop heaters have their own figures, below. The rest of the space is in outdoor room dimensions.

What clearance to combustibles means, and where you measure it#

A patio heater is a gas or electric heater built for outdoor use. It warms people by radiant heat, the way the sun does, rather than by warming the air. The common kind is the standing propane heater: a tall post, a burner at the top and a round reflector over it. That shape is why it is called a mushroom heater. A pyramid heater burns inside a glass tube. Others sit on a table or fix to a wall or ceiling.

Clearance to combustibles is the gap each manual sets between the heater and anything that can burn. Schwank defines it as "the minimum distance that must be maintained between the outer heater surface and a nearby surface." At that distance the nearby surface warms to 90 F (50 C) above room temperature, in Schwank's test. Bromic's Australian manual uses 65 C.

Combustible is wider than most people think. Sunglo's manual lists "wood, compressed paper, plant fibers, plastic, Plexiglas" and anything else that can burn, and they count "even though flame-proofed, fire-retardant treated or plastered." So a plastered ceiling over timber joists still counts. Sunglo adds that glass and painted surfaces may need more room.

Three gaps are measured.

• Above. From the top of the heater, usually the reflector, to the lowest thing overhead that can burn: a rafter, beam, fan or fabric, not the ceiling boards behind it.
• Sides. From the outer edge, on a mushroom heater the rim of the reflector, to the nearest wall, post, cushion or plant. Schwank's drawing marks it "Sides of Reflector".
• Below. From the reflector down. Few standing heater manuals print it; Schwank prints 24 in (61 cm).

Eighteen to 48 in above: what the manuals print#

There is no single figure, because each heater is listed with its own. These are the standing heaters, read from their manuals.

Across makers, the figure above runs from 18 to 48 in, and to the sides from 24 to 48 in. The pair 2 ft and 3 ft also appears in both orders. Fire Sense puts the 3 ft above; the pyramid heater puts it at the sides. So "3 ft and 2 ft" heard second-hand is not enough. You need to know which way round your model has it.

One manual can even carry two figures. The Costco UK manual gives 36 in above and 24 in to the sides, then "3.3 feet/40 inches/1 meter from top and sides" in the next warning. Plan to the larger; that is our rule, not the maker's.

The 3 to 5 ft that ranks for this question comes from a heater retailer's blog, which says "most reputable manufacturers recommend a minimum clearance of 3-5 feet". None of the manuals above prints 5 ft. The same page says most heaters need a ceiling of "at least 7-8 feet". The next section shows why no standing heater read here fits under 8 ft.

Ceiling height for a covered patio: heater height plus the top clearance#

The ceiling a heater needs is its height plus the clearance above it. The pyramid heater lists "33L x 18W x 89H inches"; the Costco UK heater lists 225 cm, or 88.6 in. So take 89 in (226 cm) as a full-size standing heater.

Work it through for a Fire Sense heater of that height. Its manual sets 36 in (91 cm) above, and 89 in plus 36 in is 125 in: 10 ft 5 in (3.18 m) from the floor to the lowest rafter or beam. Under a 10 ft (3.05 m) ceiling, the gap above would be 31 in, which is 5 in short.

Not every heater named there is 89 in tall; Sunglo and Schwank give no overall height in these manuals. The table applies each top clearance to the same 89 in heater to show the spread. For your own heater, add its height to its own figure.

24 in to a wall, and what else counts as a wall#

The side clearance applies in every direction. On a mushroom heater the reflector is the widest part, so the gap is taken from its rim, not the post. Walls are only the start. The gap applies to:

• Walls, posts and railings of timber, vinyl or painted board. Schwank and Bromic both warn that vinyl siding, fabrics, canvas and plastics can degrade at lower temperatures, and leave the installer to protect them.
• Cushions. They are fabric over foam. A sofa from outdoor sofa and lounge dimensions needs its back and arms outside the ring, not just its frame.
• Parasols and awnings. A canopy is overhead fabric, so it takes the top clearance. King's manual names awnings among the materials to protect.
• Plants. Bromic's Australian manual lists plants with walls, floors and furniture: all "must be kept 1100mm from the top and side."

Fire Sense also says to keep the heater away from "windows, air intake openings, sprinklers and other water sources", with no distance given. Schwank says the distance to sprinkler heads "may be greater than the certified clearance".

So a Fire Sense heater needs a clear circle as wide as its reflector plus 48 in (122 cm). Leave that floor free when you plan patio sizes and layouts, and mark it on the paving at full size before buying furniture. A person may stand closer than a wall can. Their clothes may not touch it: Fire Sense says "Do not hang clothing or any other flammable materials from the heater, or place near the heater."

Tabletop heaters: 18 to 24 in above, 24 to 36 in to the sides#

A tabletop heater is a short propane heater that stands on a table and runs on a small cylinder. Its clearances are not much smaller than a standing heater's.

Manuals: Fire Sense 60262, HLDS032, HPS-C-PC. The HPS-C-PC is certified to ANSI Z83.26/CSA 2.37, the US and Canadian standard for gas-fired outdoor infrared patio heaters.

The catch is the table. A six-seat table in outdoor dining dimensions is 36 in (91 cm) wide. A heater in the middle with 36 in to the sides has a ring that runs well past both edges, over the diners' laps. And a parasol through the table puts fabric straight above the heater. The top clearance is then measured to the canopy, so close the parasol or move the heater.

Wall and ceiling-mounted gas heaters: 3 ft above, 3 ft to the side, 8 ft up#

A wall or ceiling-mounted gas heater is a fixed radiant panel on a gas line. Bromic's Tungsten Smart-Heat Gas is one. Its US manual sets three distances, the same for the 26,000 BTU Tungsten 300 and the 43,000 BTU Tungsten 500.

The heat shield is a deflector sold for the heater. It cuts the gap above from 36 in to 14 in, so a heater mounted at 8 ft can sit under a much lower roof. The side gap, from the end of the heater to a side wall, stays at 3 ft. Bromic's Australian manual calls its 2,000 mm a "recommended minimum installation height".

Post-mounted infrared heaters such as the Schwank 4SN5 set 18 in (46 cm) above, 24 in (61 cm) to the sides and 24 in below the reflector. Sunglo's A270 prints 18 in to the ceiling and 84 in below, written "84” (84 cm)": a slip, since 84 in is 213 cm.

Electric infrared heaters: inches from the ceiling, 6 to 8 ft from the floor#

An electric patio heater has no flame and burns no gas. A heated element sits in front of a reflector that aims the heat down. Its clearances are far smaller, which is why it can go under an 8 ft porch.

Stelpro also says to keep combustible materials "at least 3 ft (0.9 m) away" from its heater. Bromic's electric Tungsten must not go below 96 in (8 ft) for Canadian approval, and its heaters must be 20 in (51 cm) apart, edge to edge.

Above the minimum, height is a comfort choice. King recommends 8 to 9 ft (2.4 to 2.7 m) and warns that heaters set too low or too high "may result in discomfort or lack of heat". Stelpro recommends 6 to 7 ft (1.8 to 2.1 m) on a ceiling for its smallest model, the SVI1501BK. For its largest, the SVI6002BK, it recommends 10 to 12 ft (3 to 3.7 m). Wiring is an electrician's job, and wet locations have their own rules, some set out in hot tub clearances.

Enclosed patios: the 25 and 30 per cent test#

A gas heater uses up oxygen and makes carbon monoxide, so the manuals also limit how enclosed its space may be. Fire Sense is strict: "Heater is for use outdoors (outside any enclosure)." The pyramid heater excludes "partially enclosed outdoor areas such as tents."

Bromic, Schwank and Master Forge allow three kinds of shelter. Bromic words them most fully. The heater may be used:

1. In "an enclosure with walls on all sides, but at least one permanent opening at ground level". Master Forge adds: with no overhead cover.
2. Under "an overhead cover and no more than two walls". Schwank adds that the walls "may be parallel, as in a breezeway, or at right angles".
3. Under an overhead cover with more than two walls, if "at least 25% of the total wall area is completely open" and "at least 30% of the remaining wall area is open and unrestricted".

Master Forge prints the same 25 and 30 per cent test. Schwank's third case instead asks for "30 percent or more of the horizontal periphery" to be permanently open: a share of the length round the edge, not of wall area.

Work Bromic's test through for a covered patio 12 ft wide and 10 ft deep under a 9 ft roof, with the house at the back and walls on both sides. Counting the open front, the four walls total 396 sq ft (36.8 m2). The open front is 108 sq ft, 27 per cent, so the first part passes. The other 288 sq ft (26.8 m2) then needs 30 per cent open: 87 sq ft (8.1 m2), almost a whole 90 sq ft side wall. A window in each side wall will not reach it. Measure your own walls and convert them in the unit converter.

A grill under the same roof is a separate appliance with its own manual, and under a solid roof it needs a hood, as outdoor kitchen dimensions explains.

Where these figures stop applying#

The clearances here are minimums from the manuals named, for those models only. Another heater may need more. Your heater's own manual and label decide, and where they differ, use the larger figure. A heat shield changes the figure only if the maker sells it for that heater.

This page quotes no building or fire code clearance for patio heaters. The manuals say installation must follow local codes or, where there are none, the National Fuel Gas Code (ANSI Z223.1/NFPA 54). For a business or a shared building, ask the local fire marshal before relying on any figure here. The codes this site does quote are listed under standards and codes.

Confirm with the maker what the manuals do not say: whether insect screen counts as an open wall, and whether a heat shield is sold for your model. Fire Sense limits use to wind below 10 mph, and Bond keeps a separate propane tank at least 5 ft (1.5 m) away when lit. A wood fire is a different appliance with far larger distances, set out in fire pit clearances. Metric figures here are conversions, as imperial and metric dimension systems explains.