Landscaping
Outdoor fire feature field guide: fire pits, fireplaces, clearances, and gas
What makes a fire pit or outdoor fireplace safe: the clearances that keep fire and sparks off the house and the overhead, and, for gas, the rated burner, the rated media, and the vented enclosure.
Direct answer
An outdoor fire feature is a fire pit or fireplace, often gas-fed, built into a backyard. Two things make it safe: the clearances that keep fire, radiant heat, and sparks off the house, the combustibles, and the overhead, and, for gas, a rated burner, a vented enclosure, and rated media. The fuel gas code, the manufacturer, and the AHJ govern.
Key takeaways
- Open wood-burning fire pits commonly sit 10 to 25 ft from the house, fences, and combustibles; listed gas units sometimes allow as little as 36 in.
- Use only rated fire glass or vesicular lava rock; regular stone, river rock, and pea gravel trap water that flashes to steam (expanding roughly 1,700x) and explodes.
- Never place an open wood fire under a pergola, eave, fabric, or branches; gas under cover is allowed only if the manufacturer lists it, often 7 to 10 ft overhead.
- An enclosed gas burner needs low vents on opposing sides so a leak escapes; propane is heavier than air and pools low, so an unvented cabinet can explode.
- Natural gas carries about 1,000 BTU per cubic foot and needs no air mixer; propane carries about 2,500 BTU and requires an air mixer and matched orifice.
What a fire feature is and what actually makes it safe
An outdoor fire feature is fire, and often gas, sitting in the backyard a few feet from the people who paid for it. That is the whole job in one sentence, and it is why two things decide whether the feature is a good night or an incident: the clearances and the gas. The clearances keep the fire, the radiant heat, and the sparks away from the house, the combustibles, the overhead, and the deck. The gas, where there is gas, has to be the right burner with the right fuel setup, a media that will not explode, and an enclosure that cannot trap a leak.
Everything else is finish. The stone, the shape, the seat wall, the fire glass color all matter to the customer and none of them matter to safety. A beautiful fireplace built three feet from a cedar fascia under a wood pergola is a fire waiting for the wind. A gas pit with the wrong rock and no enclosure vents is a shrapnel and explosion problem dressed up as outdoor living.
So the work, the part you cannot shortcut, is building to the clearances, running the gas to code, and using rated media. The patio it sits on is its own scope, covered in the paver and hardscape installation guide. The propane supply, if the feature runs on LP, is its own scope too, covered in the propane and LP-gas system install guide. This guide stays on the fire feature itself, and it hedges hard on the numbers, because the manufacturer listing, the fuel gas code, the fire code, and the local AHJ control them, not a rule of thumb.
Clearances and the gas: the two that make or break it
If you remember one thing from this guide, make it this. A fire feature lives or dies on its clearances and, when it burns gas, on how the gas is done. Those are the two failure modes that hurt people. Everything else is a callback you can fix on a Tuesday.
Clearance is distance, in three directions. Away from the house and any combustible wall, fence, or shed. Away from anything overhead, a pergola, an eave, a low branch. And, if the feature sits on a deck, away from the wood under it, which usually means a non-combustible base and the manufacturer's blessing or nothing at all. Heat and sparks do not care how good the masonry looks.
Gas is the second axis. A gas feature needs a burner rated and set up for the fuel it burns, rated fire glass or lava rock rather than regular stone, and, when the burner sits in an enclosure, low vents so a leak cannot pool. Propane is heavier than air and sinks, so an unvented cabinet is the dangerous case. Get the clearances and the gas right and the rest of the build is craft. Get either one wrong and the craft does not save you. Hedge both to the manufacturer, the fuel gas code, the fire code, and the AHJ.
What types of outdoor fire feature are there?
Outdoor fire features split first by fuel, and the fuel changes almost everything downstream: the clearances, the structure, the maintenance, and the permit. Wood-burning means a fire pit ring or a masonry fireplace with a chimney, the classic open fire. It throws sparks, it makes smoke the neighbors will notice, and it needs more clearance and clear sky above it. Gas means a burner fed by natural gas or propane, burning over rated media, clean and controllable with a valve.
Neither is better in the abstract. Wood-burning is cheaper to build and gives the real fire experience, at the cost of smoke, sparks, ash, and the days a local burn ban shuts it down. Gas costs more up front and brings the burner, the gas line, and the venting into scope, and in return it lights with a key or a button, makes no sparks, and goes out when you close the valve. The table below is the short version. The manufacturer and the AHJ set the actual numbers.
| Factor | Wood-burning (fire pit / fireplace) | Gas (natural or propane / LP) |
|---|---|---|
| Fuel | Cordwood, on site | Natural gas line or propane tank |
| Sparks and embers | Yes, needs a spark screen and more clearance | None from the burner itself |
| Smoke | Yes, drifts to neighbors, draft matters | Effectively none |
| Control | Light it, feed it, let it burn down | Valve on and off, adjustable |
| Clearance need | Larger, no overhead at all over open flame | Smaller, but enclosure must vent |
| Media | Fire grate or open hearth | Rated fire glass or lava rock only |
| Added scope | Chimney, draft, spark arrestor | Burner, gas line, enclosure venting |
| Governing | Fire code, NFPA 211, AHJ, burn rules | Fuel gas code, manufacturer, AHJ |
How far should a fire feature be from the house?
Far enough that the radiant heat and the sparks never reach a combustible, and the exact distance depends on the fuel and the manufacturer, not on a single number you can carry around. For an open wood-burning fire pit, common guidance puts it on the order of 10 to 25 ft from the house, the fence, the shed, and anything that can catch, because embers travel and radiant heat scorches siding from farther than people expect. A listed gas feature is different. Its instructions often allow as little as 36 in to a combustible structure because the flame is contained and there are no flying embers, while some natural-gas pits are held around 10 ft. The listing is the authority for a listed unit.
Three directions matter, and people only think about one. Horizontal clearance to the house and combustibles is the obvious one. The property line is the second, because a fire too close to the line is both a code problem and a neighbor problem. And the seating distance is the third, the one nobody calls clearance, where the radiant heat reaches the people. Set the seats too close and the customer roasts on one side and freezes on the other.
Do not treat any number in this section as a permit. Fire pit and outdoor-fireplace clearances are set by the fire code the jurisdiction has adopted, by the appliance listing for a manufactured unit, and by local amendments and HOA rules that can be stricter than all of them. Pull the manufacturer's clearance table for the specific unit and confirm the rest with the AHJ before you set the footing.
| Direction | What it protects | Common guidance (verify with AHJ and manufacturer) |
|---|---|---|
| To house and combustibles | Siding, fence, shed from radiant heat | Wood often 10 to 25 ft; listed gas sometimes 36 in |
| Overhead | Pergola, eave, branches, fabric | No open flame under cover; gas often 7 to 10 ft min |
| On a deck | The wood or composite surface below | Non-combustible base plus manufacturer approval, or no |
| Property line | Code setback and the neighbor | Per local fire code and HOA |
| Seating | The people from radiant heat | Comfort distance, not a code number |
Can you put a fire pit under a pergola or a tree?
For an open wood-burning fire, the answer is no, and it is one of the firmest calls in this guide. Open flame throws sparks and a column of hot gas straight up, and a pergola, a roof overhang, an eave, fabric shade, or a low tree branch sits right in that column. The sky has to be open over an open fire. Treat overhanging branches as combustible even when they look green, because the heat dries them out over a season and then a spark finds them.
Gas under cover is a different question with a different answer. A contained gas flame makes no embers, so a listed gas feature can sometimes go under a structure if the manufacturer allows it, and that always comes with a minimum overhead clearance and the venting requirements that follow from putting a gas burner in a partly enclosed space. Vendors commonly cite overhead clearances in the range of 7 to 10 ft to combustible cover for gas units, but the listing for the specific feature is what governs, not a blog number.
The practical rule is short. No open fire under anything. Gas under cover only if the manufacturer's instructions say so, at the clearance and the venting they specify, confirmed with the AHJ. When the customer wants fire under the new pavilion, that is a gas feature with a listed clearance, not a wood pit you talked yourself into.
Can you put a fire pit on a wood deck?
Not without protection, and often not at all, because a fire pit drives serious heat straight down into a surface that cannot take it. A burning pit can reach around 800 degrees F, and it can transfer roughly 200 to 400 degrees F of radiant heat into whatever sits under it. Wood, composite, and vinyl decking absorb that and scorch, char, or ignite. Add the embers a wood fire spits and an unprotected wood deck is a bad bet.
If a deck is the only option, the fix is a non-combustible base under the feature plus the manufacturer's explicit approval for deck use. That usually means a heat shield or a fire-rated mat built to take 1000 degrees F or more, or a base of concrete pavers or stone, with the protection extending well past the footprint of the fire, commonly on the order of 24 in on all sides. Many manufactured gas pits with legs and a heat barrier are listed for decks; most open wood pits are not. The unit's listing decides, not the mat alone.
Gas changes the math but does not erase it. A listed gas pit on legs runs cooler underneath and makes no embers, so deck installs are more common on the gas side, still only when the listing allows it and the base is right. For the deck structure itself, the framing, and the surface protection details, defer to the deck and the manufacturer. Hedge every distance here to the manufacturer's instructions, the fire code, and the AHJ, and when none of them clearly bless a fire on that deck, the answer is no.
The wood-burning fire pit and fireplace
Wood-burning is the simple fire and the complicated structure. A fire pit is a non-combustible ring or bowl, often a masonry block ring with a steel or refractory liner, holding an open wood fire. A wood-burning outdoor fireplace adds the firebox, the throat, the smoke shelf, and the chimney, and those parts exist to do one job: pull the smoke up and away instead of into the faces of the people in front of it.
Draft is what people underbuild. A fireplace that will not draw spills smoke out the front, and the cause is usually a flue sized wrong or a chimney too short to develop the pull. The flue cross-section is keyed to the size of the fireplace opening, with masonry-fireplace rules commonly putting the flue area near 1/10 to 1/12 of the opening area depending on flue shape, and the chimney has to be tall enough to draft. Get the opening-to-flue ratio wrong and no amount of dry wood fixes the smoke.
Sparks are the second wood-burning hazard, and the answer is a spark screen or a spark arrestor. A fire pit needs a screen over the top to stop embers from popping out toward people, the deck, or the dry grass. A chimney needs an arrestor at the top, sized with enough open area to avoid choking the draft, commonly several times the flue outlet area. And then there are the days you simply cannot light it. Local burn bans shut down open wood fires on high-fire-danger or air-quality days, and that is the AHJ's call, not yours. No deck, no overhead, a screen on the fire, and more clearance than a gas feature would need. Confirm the specifics against the fire code, NFPA 211 for the chimney, and the local burn rules.
The gas fire feature
A gas fire feature trades the wood for a burner, and the appeal is real: it lights with a key or a button, it makes no sparks or smoke, it adjusts with a valve, and it goes dead out when you close the gas. It runs on natural gas off a house line or on propane from a tank, and that fuel choice drives the burner setup, the orifice, and the venting, which the propane and LP-gas system install guide covers from the supply side.
The feature itself is a few parts that all have to be right. A rated burner sized to the heat output you want, set up for the fuel it burns. A pan that holds the burner and the media and drains water instead of holding it. Rated fire glass or lava rock over the burner, never regular stone. An ignition, from a match-lit valve up to an electronic system with flame sensing. And a shutoff, a key valve you can reach without putting your hand over the flame.
The thing pros respect about gas is that it is unforgiving in a quiet way. A wood fire that is built wrong looks wrong. A gas feature that is built wrong, the wrong orifice, the wrong media, an unvented box, looks perfect right up until it does not. So the gas side gets the burner, the media, the ventilation, and the gas line each done to the manufacturer and the fuel gas code, and proven, before anyone calls it finished.
The burner and the pan
The burner is the heart of a gas feature, and it has to match the fuel. Natural gas and propane do not carry the same energy or burn the same way. Roughly, a cubic foot of natural gas gives about 1,000 BTU while the same volume of propane gives about 2,500 BTU, so the two need different orifice sizing to deliver the right flame, and a burner or orifice set for one fuel run on the other burns wrong. Too rich and you get soot and a lazy yellow flame; too lean and you get lifting and poor combustion.
Propane brings an extra part most people miss: the air mixer. Propane needs more combustion air than natural gas, so a propane fire feature uses an air mixer, a venturi that pulls in ambient air as the gas speeds through a narrowed throat, to get a clean burn. Natural gas generally does not need one. Install a propane burner without the right air mixer or orifice and the flame sooner blackens the media and the surrounds with soot.
The pan holds the burner and the media and it has to drain. Rain and snow get into an outdoor pan, and water that sits around the burner corrodes it and, worse, soaks into porous media so it can flash to steam later. A proper pan has weep holes or a drain so water leaves. Size the burner to the BTU you want, match the orifice and the air mixer to natural gas or propane, and let the pan shed water. Confirm the burner, the orifice, and the BTU rating against the manufacturer and the fuel gas code for the fuel you are actually feeding it.
Why does fire pit rock explode?
Because regular stone traps water, and trapped water turns to steam under the fire. Water expands roughly 1,700 times its volume when it flashes to steam, and a closed pocket of moisture inside a rock has nowhere to send that pressure, so the rock cracks and throws shrapnel. River rock is the worst offender: it is rounded because it sat in water, so it is saturated, and its tight surface holds the steam in instead of letting it breathe out. Pea gravel and ordinary landscape stone do the same thing.
This is the single most important safety rule on the gas-media side, and it is simple. Use only rated fire glass or rated lava rock, and nothing else. Tempered fire glass is manufactured to take the temperature swing without shattering. Lava rock is vesicular, meaning it formed in heat and is full of tiny open pores, so any moisture vents out through the holes instead of building pressure. Both are sold dry and rated for fire features for exactly this reason.
Two field habits go with the rule. First, never substitute decorative rock from the yard or the landscape pile to save a few dollars, because the customer is sitting two feet from it. Second, keep even rated media reasonably dry and let it warm gradually, since lava rock can still hold some water after a heavy rain. Hedge the media spec to the manufacturer's listed media for the burner, but never hedge the core rule: rated fire glass or lava rock only, regular stone never.
Why does an enclosed gas fire feature need venting?
Because gas can leak, and an enclosed cabinet with no vents lets it collect until an ignition source finds it. This is the number one safety item on the enclosure side of a gas feature, and it is non-negotiable: a gas burner sitting inside a masonry or metal enclosure has to be vented so any leaking gas escapes instead of pooling. With propane the danger is sharpest, because propane is heavier than air, so it sinks and pools at the low point of the box rather than rising and drifting off. An unvented propane enclosure is how a fire feature becomes an explosion.
Venting means openings low on the enclosure, on opposite sides, so gas can flow out and air can cross through. Common guidance is at least two vents on opposing sides placed low, near the bottom, with vendors often citing minimums on the order of 18 square inches per vent for a typical feature, sized up with the enclosure and the tank. Natural gas, being lighter than air, calls for venting placed higher, but the principle holds either way: a leak must have a path out of the box.
Do not improvise this. Vent area, vent placement, and whether a given enclosure is acceptable at all are set by the manufacturer's instructions for the burner and pan, by listings such as ANSI Z21.97 and CSA 2.41 for decorative gas appliances, and by the fuel gas code, NFPA 54, with the fire code and the AHJ over the top. The propane and LP-gas system install guide covers why heavier-than-air gas pools low in more depth. Build the vents in before the stone goes up, because you cannot add them later without tearing into the feature.
The gas line, the shutoff, and the leak test
A gas fire feature is only as safe as the line feeding it, and that line is licensed work in most places. The pipe has to be sized for the burner's demand, because a line too small starves the burner and a line shared with other appliances has to carry the whole load. Undersize it and the flame falls off when the furnace or the range comes on. The sizing comes off the gas tables for the fuel, the length of the run, and the total connected load.
Every gas feature needs an accessible manual shutoff, commonly a key valve, within reach and dedicated to the appliance. The fuel gas code generally wants a manual valve close to the appliance, often within about 6 ft, so anyone can kill the gas fast without reaching across the fire. Place the key so the user turns it without leaning over the flame.
Then you prove it. A new gas line gets pressure-tested and leak-checked before gas reaches the burner, and that test belongs in the record. This is licensed gas work tied to a permit in nearly every jurisdiction, performed by a qualified gas fitter, and inspected. The supply side, the tank, the regulators, and the propane sizing live in the propane and LP-gas system install guide. Size the pipe, set an accessible shutoff, test it tight, and pull the permit. Hedge the sizing, the shutoff placement, and the test to NFPA 54, the manufacturer, and the AHJ.
Propane vs natural gas: what gas does a fire feature use?
Both, and which one changes the setup more than people expect. Natural gas comes off the house line, lighter than air, carrying about 1,000 BTU per cubic foot, and it needs no tank and no air mixer at the burner. Propane, or LP, comes from a tank through a regulator, heavier than air, carrying about 2,500 BTU per cubic foot, and it needs an air mixer for clean combustion. The two are not interchangeable at the burner without changing the orifice and, for propane, adding the mixer.
The heavier-than-air fact is the safety divider. Natural gas that leaks rises and dissipates. Propane that leaks sinks and pools low, in the enclosure, in a pit, in any cavity below the burner, which is why propane drives lower enclosure vents and a tank set to its own setbacks. A leak that would drift away on natural gas can sit and wait on propane.
Pick the fuel by what the site has. A house with a natural-gas main usually feeds the feature off that line. A property with no main runs propane, which brings the tank, the regulator, and the LP-specific sizing and venting into scope. Either way the orifice, the air mixing, and the venting are matched to the fuel, never assumed. The propane side, including why it pools low and how the tank and two-stage regulators fit, is the subject of the propane and LP-gas system install guide.
The structure: ring, masonry, footing, and chimney
The structure is what holds the fire and keeps the heat out of everything around it, and it is non-combustible from the fire out. A fire pit is a ring or a bowl, often masonry block faced over a steel or refractory liner that takes the direct heat so the decorative block does not spall. The liner is the part that earns its keep: bare block against repeated fire cracks and crumbles, while a liner takes the thermal beating.
An outdoor fireplace is a bigger build and it carries weight. The chimney and firebox need a real footing, sized and reinforced for the mass and set below frost where freeze-heave is a factor, because a fireplace that settles cracks and a cracked flue leaks smoke and heat. Guidance commonly puts the footing wider than the walls on each side and thick enough for the stack it carries, with the exact size set by the soil, the height, and the local code.
Above the firebox, the firebox lining, the throat, the smoke shelf, the flue, and the chimney cap all do real work, and the chimney gets the spark arrestor at the top. None of it is decorative. The fire-side surfaces are firebrick or refractory because ordinary masonry will not survive the heat. Build the non-combustible liner, set the footing for the load and the frost, and size the flue to the opening. Confirm the footing, the firebox, and the chimney against the IRC chimney and fireplace provisions, NFPA 211, and the AHJ.
The ignition
On a gas feature, the ignition is how you start the fire and, on the better systems, how the feature protects itself. The cheapest is match-lit: open the key valve and touch a long lighter to the burner. It is reliable and simple and it has no safety shutoff, so if the flame blows out the gas keeps flowing until someone closes the valve.
A spark ignition adds a battery-powered igniter at the burner so you push a button instead of reaching in with a flame. A flame-sensing system goes further, watching the flame and shutting the gas if it goes out, which closes the gap the match-lit setup leaves open. A full electronic ignition runs the valve through a control box, often with a thermopile or flame sensor, and supports features like a timer or a remote.
The safety logic is the part that matters more than the convenience. Any ignition above match-lit can include flame sensing that kills the gas on a flameout, and on a feature near seating that is worth the cost. Match-lit is fine where someone is always present and the valve is right there. Pick the ignition to the use and the budget, and let flame sensing decide the close calls. Match the ignition system to the burner and the fuel per the manufacturer.
Do you need a permit for an outdoor fire feature?
Usually yes, and on a gas feature almost always, because two separate code worlds touch a fire feature: the fuel gas side and the fire side. The gas line and the burner connection are licensed gas work that typically needs a permit and an inspection, performed by a qualified gas fitter, under the fuel gas code the jurisdiction has adopted. Skipping that permit is the kind of shortcut that voids insurance after an incident.
The fire side is the clearances, the construction, and whether open burning is even allowed. The fire code sets the distances to combustibles and the rules for open flame, local ordinances and burn bans govern when a wood fire can be lit at all, and an HOA can be stricter than any code on top of that. A wood-burning fireplace also pulls in the chimney provisions for the flue and the structure.
Run it legal from the start. Confirm whether the feature needs a gas permit, a building permit for the structure, or both, check the fire-code clearances and the local burn rules, and clear it with the HOA before the footing goes in. The adopted code edition, the local amendments, and the AHJ control all of it, so the only safe move is to ask the AHJ what the specific jurisdiction requires rather than assume it from another job.
The seating and how it gets used
Seating is where the clearance question meets comfort, and it gets designed by feel more than by table. People want to be close enough to feel the warmth and far enough that the radiant heat is pleasant rather than punishing, and that distance depends on the size of the fire and the output of the burner. A big fireplace pushes heat farther than a small bowl, so the seats sit back accordingly.
Wind and smoke set the layout as much as the heat. A wood-burning fire sends smoke downwind, so you place the seating and the feature with the prevailing wind in mind, and you accept that on a shifting evening someone will eat smoke no matter what. Gas sidesteps the smoke but still moves heat with the wind. Leave a path around the feature so people are not trapped between the fire and a wall when they want to move.
Capacity is the quiet design input. A feature sized for a couple feels lost in a crowd, and one sized for a party cooks the two people who use it most nights. Size the fire and the seating to how the customer actually lives in the yard, keep a clear walk-around, and respect that the seating distance is a real clearance even though no code calls it one.
The build sequence
The order of operations on a fire feature protects the parts you cannot easily reach later, and the gas and the venting are the parts you cannot reach later. Get them in before the stone closes them up.
The base and the structure go first: the footing or the prepared base, then the ring or the firebox and the enclosure, built non-combustible with the liner in place. On a gas feature the gas line and the burner and pan come next, set and connected while the enclosure is still open, with the enclosure vents formed in low and on opposing sides as the masonry goes up. Then the test, before anything covers the line: pressure-test and leak-check the gas, light and confirm the burner, and only then proceed. After the gas proves out, the rated media goes over the burner, fire glass or lava rock, never regular stone. The finish stone, the cap, the spark screen or arrestor, and the seating close it out.
The sequence exists so nothing important hides behind finished work. Bury an untested gas line under stone and you are tearing the feature apart to find the leak. Forget the vents and you are coring a finished enclosure. Build the structure, run and prove the gas, vent the box, set the rated media, then finish. Hold that order and the feature is safe before it is pretty.
Operating and shutting down safely
A fire feature is safe to build and still dangerous to use carelessly, and the operating rules are the ones the customer needs more than the crew. The first is the oldest: never leave a fire unattended. An open wood fire throws embers, and a gas flame that blows out on a match-lit unit keeps feeding gas until someone closes the valve.
Wind, kids, and pets are the three things that turn a calm night bad. Wind carries embers and shifts the flame, so a gusty night is a night to keep the fire small or skip it. Kids and pets do not read radiant heat the way adults do, and the surfaces around a fireplace stay hot long after the flame is down. Keep a clear zone and an adult watching.
Shutting down is its own step. A wood fire gets fully extinguished, not left to smolder, before everyone goes in, because a banked fire can find an ember hours later. A gas feature gets the key valve closed, and on a propane feature the tank valve too, so no gas can creep out of a burner that is not lit. Never unattended, smaller in wind, kids and pets clear, and the gas fully off when you leave it.
Maintenance
A fire feature that gets a little attention each season outlasts one that gets none, and the maintenance splits by fuel. On a gas feature, the burner ports clog with soot, spider webs, and debris, and a clogged burner burns uneven or lights with a thump, so the burner gets cleaned and the ports cleared on a schedule. The media gets checked and replaced as it breaks down, and a gas check confirms the connections are still tight.
Wood-burning features carry their own list. The spark screen and the arrestor catch soot and need cleaning, the firebox and the chimney accumulate creosote and ash that a wood-burning chimney needs swept, and the masonry gets inspected for cracks and spalling where the heat works on it hardest. A cracked liner or a fouled flue is a smoke and fire problem, not a cosmetic one.
Across both, a cover keeps water out of the pan, the burner, and the media between uses, which heads off the corrosion and the trapped-moisture problem that makes media dangerous. Clean the burner or sweep the chimney, check the media, confirm the gas connections, cover it when it is cold. Keep the gas and chimney service to the manufacturer's intervals and a qualified pro.
Field checklist
Want this checklist to run itself on every job — with photo proof and a signed record crews can hand the customer? That's FieldOS.
What to document
A fire feature is a fire and a gas appliance in someone's yard, so the record is what proves it was built right when an insurer, an inspector, or a future owner asks. The valuable records are the safety-critical ones: the clearances you held, the gas test that passed, the venting you built, the rated media you installed, and the permits you pulled. A photo of the open enclosure before the stone goes up, showing the vents and the tested line, is worth more than any verbal assurance later.
A field tool such as FieldOS keeps the clearance measurements, the burner and media specs, the gas pressure-test result, the vent layout, the permit numbers, and the photos attached to the job, so the proof stays with the property instead of in a truck. The table below is the short list of what to capture and why it matters.
| Item | Requirement | Note |
|---|---|---|
| Clearances | Per manufacturer and fire code | House, combustibles, overhead, deck, property line |
| Overhead | Open sky over open flame | Gas under cover only if listed, with vents |
| Gas burner | Rated, correct orifice and air mixer | Matched to natural gas or propane |
| Media | Rated fire glass or lava rock only | Never river rock or regular stone |
| Enclosure venting | Low vents, opposing sides | Propane pools low, must escape |
| Gas line | Sized, shutoff, leak-tested | Licensed work, pressure test recorded |
| Permits | Gas and fire, plus HOA | AHJ controls; keep the numbers |
Common mistakes
- Setting the fire too close to the house, or under a pergola, an eave, or a tree, where heat and sparks reach combustibles.
- Putting a fire pit on a wood deck with no non-combustible base and no manufacturer approval.
- Using river rock, pea gravel, or regular stone that traps moisture, flashes to steam, and explodes.
- Leaving a gas burner in an enclosure with no low vents, so a propane leak pools and waits for ignition.
- Running the wrong orifice or skipping the air mixer for the fuel, so the burner soots or burns lean.
- Sizing the gas line too small or omitting an accessible key shutoff near the feature.
- Skipping the gas permit, the fire-code clearances, or the local burn rules and the HOA.
- Burying the gas line under finished stone before it is pressure-tested and proven tight.
Standards and references
The gas side answers to the fuel gas code. NFPA 54, the National Fuel Gas Code, also published as ANSI Z223.1, covers the piping, the sizing, the shutoff, and the connection for natural gas, and the propane supply side runs under NFPA 58, the LP-Gas Code, both in the propane and LP-gas system install guide. Listings such as ANSI Z21.97 and CSA 2.41 cover decorative gas appliances and inform the enclosure venting. The burner, the pan, the orifice, the air mixer, the rated media, and the clearances are set first by the manufacturer's instructions for the specific listed feature.
The fire side answers to the fire code and the chimney standards. The clearances to combustibles and the rules for open flame come from the adopted fire code, NFPA 1 in many jurisdictions, with local burn ordinances controlling when a wood fire can be lit. A wood-burning fireplace and its chimney fall under the chimney and fireplace provisions of the residential code and NFPA 211 for the flue sizing, the spark arrestor, and the structure. The patio and base are covered in the paver and hardscape installation guide.
Hold the clearances so fire and sparks stay off the house, the combustibles, and the overhead. Use only rated fire glass or lava rock, never regular stone that explodes. Run the gas to code and vent the enclosure so gas cannot pool. Those three are the spine of a safe fire feature. Every number in this guide is a starting point to verify, because the manufacturer listing, the fuel gas code, the fire code, the adopted code edition, the local amendments, the HOA, and the AHJ control the actual requirements, and the gas work belongs to a licensed gas pro.
Units and terms
Fire-feature work borrows terms from masonry, from the gas trade, and from the fire code, so the same part can be called different things across a spec sheet, a permit, and a manufacturer manual.
Heat output is in BTU, and the same volume of propane carries roughly two and a half times the BTU of natural gas, which is why the orifice differs. Clearance is given in feet and inches and is always to a reference, the house, the combustible, the overhead, so a clearance number with no reference is incomplete. Vent area is in square inches. Keep the fuel, the clearance reference, and the rated media named on every record.
- Fire feature
- A fire pit or outdoor fireplace built into a yard, wood-burning or gas
- Fire pit / outdoor fireplace
- An open ring or bowl, versus a masonry firebox with a chimney that drafts smoke up
- Clearance to combustibles
- The distance from the fire and its heat to anything that can burn, horizontal and overhead
- Wood-burning vs gas
- Open wood fire with sparks and smoke, versus a controllable gas burner over rated media
- Rated fire media
- Fire glass or lava rock made for fire features; regular stone traps moisture and can explode
- Burner / pan / orifice
- The gas flame element, the tray that holds it and the media, and the metered gas opening sized to the fuel
- Air mixer
- A venturi that adds combustion air to propane for a clean burn; not needed for natural gas
- Enclosure ventilation
- Low opposing vents that let a gas leak escape instead of pooling in the cabinet
- LP vs natural gas
- Propane is heavier than air and pools low from a tank; natural gas is lighter and comes off a line
- Spark screen / arrestor
- A mesh over a fire pit or at a chimney top that stops embers from escaping
FAQ
How far should a fire pit be from the house?
Far enough that heat and sparks never reach a combustible. Open wood pits commonly sit on the order of 10 to 25 ft from the house, fences, and sheds, while a listed gas pit may allow as little as 36 in. The manufacturer listing, the fire code, and the AHJ set the real distance.
Can you put a fire pit on a wood deck?
Only with a rated non-combustible base and the manufacturer's approval, and often not at all. A pit can hit around 800 degrees F and drive 200 to 400 degrees F into the deck below. A listed gas pit on legs with a heat barrier is more likely allowed; most open wood pits are not.
Why does fire pit rock explode?
Regular stone traps moisture, and trapped water flashes to steam under the fire, expanding roughly 1,700 times with nowhere to go, so the rock cracks and throws shrapnel. River rock and pea gravel are the worst. Use only rated fire glass or vesicular lava rock, which vents steam instead of building pressure.
What gas does an outdoor fireplace use?
Either natural gas off a house line or propane from a tank. Natural gas is lighter than air and carries about 1,000 BTU per cubic foot; propane is heavier, pools low, carries about 2,500 BTU, and needs an air mixer. The orifice and venting are matched to the fuel, never assumed.
Can you put a gas fire pit under a covered patio or pergola?
Sometimes a listed gas feature can, because it makes no embers, at the overhead clearance and venting the manufacturer specifies, often in the 7 to 10 ft range to combustible cover. An open wood fire never goes under cover. Confirm the listing and clear it with the AHJ before building.
Does an enclosed gas fire pit need to be vented?
Yes. A gas burner in an enclosure must have low vents on opposing sides so a leak escapes instead of pooling. Propane is heavier than air and sinks, so an unvented cabinet can fill and explode. Vent area and placement follow the manufacturer, ANSI Z21.97, NFPA 54, and the AHJ.
Do you need a permit for an outdoor fire feature?
Usually, and almost always for gas. The gas line is licensed work needing a permit and inspection under the fuel gas code, and the fire side has clearance rules, burn ordinances, and HOA limits. Confirm whether you need a gas permit, a building permit, or both with your local AHJ first.
Do you need an air mixer for a propane fire pit?
Yes, generally. Propane needs more combustion air than natural gas, so a propane fire feature uses an air mixer, a venturi that pulls in ambient air, for a clean burn. Natural gas usually does not. Skip the mixer or use the wrong orifice and the flame soots and blackens the media and surrounds.
What size flue does an outdoor fireplace chimney need?
The flue is sized off the fireplace opening, with masonry guidance commonly putting the flue area near 1/10 to 1/12 of the opening depending on flue shape, plus enough chimney height to draft. Undersize it and smoke spills out the front. Confirm against NFPA 211, the residential code, and the AHJ.
How do you put out a gas versus a wood fire feature?
Close the key valve on a gas feature, and on propane shut the tank valve too, so no gas creeps from an unlit burner. A wood fire gets fully extinguished, never left to smolder, since a banked fire can find an ember hours later. Never leave either one unattended.
People also ask
Codes cited in this guide
This guide is written and reviewed against the published standards below. Always confirm the current adopted edition with the authority having jurisdiction.