Cast Iron vs Steel Fire Pit: Which Suits Your Garden?

Choose cast iron if you want a fire pit that stays outside all year, holds its warmth after the flames drop and develops a rustic patina. Choose steel if you want something lighter that heats up quickly and is easy to move, and you are happy to store it indoors in winter. That is the core of it, according to Ideal Home’s fire pit buying guide: cast iron is heavier but more durable, slower to heat but better at holding heat, and better able to cope with harsh weather.

The rest of this guide helps you turn that into a decision for your own patio: how each metal behaves on a cold November evening, what upkeep to expect, where to put the fire pit and which UK rules apply.

TL;DR

• Cast iron: heavier, slower to warm up, holds heat for longer and is better suited to staying outdoors through the seasons.
• Steel: lighter and quicker to heat, easier to carry about, and best stored indoors when not in use to prolong its life.
• Rust: a cast iron fire bowl is designed to rust gently outside, forming an attractive patina, so a little surface colour is normal.
• Safety: keep the fire pit steady, away from decking, trees and structures, and have water, sand or a hose to hand.
• Smoke: check whether you live in a smoke control area and burn suitable fuel.

Table of Contents

• The difference between cast iron and steel at a glance
• Heat: quick glow or slow, steady warmth
• Durability and rust: what to expect outdoors
• Weight and where it will sit
• Fire pit or chiminea?
• Can cast iron withstand fire?
• Where to put it and how to use it safely
• How to choose: five questions
• Our view
• Find your fire pit or chiminea
• FAQ
• Sources

The difference between cast iron and steel at a glance

Both are iron-based metals, but they are made differently and that shows in how a fire pit feels and performs. Cast iron is poured into a mould, which gives it thick, dense walls. Steel is usually formed from sheet or plate, so it is thinner and lighter for the same size.

In practice, that gives you this comparison:

The weight, heat-up, heat-retention and storage points come from the Ideal Home guide. They match the general pattern you will see across fire pit guides: heavy metal with high thermal mass warms slowly and keeps the warmth, while thinner metal responds quickly and cools quickly too.

Heat: quick glow or slow, steady warmth

This is the difference you will notice first.

A steel fire pit responds fast. Light the fire and the bowl warms within a short time, which suits a spontaneous half hour after work or a quick get-together. The flip side is that when the flames die down, the warmth goes with them.

Cast iron needs longer to absorb the heat. Once it has, the metal keeps radiating warmth after the flames have dropped, so the second hour of an evening feels more comfortable than the first. If you tend to sit out for long dinners or let the fire burn down while you chat, that steady output is the better fit.

A practical way to choose: think about how long you usually sit outside. Under an hour, steel’s quick start is a real advantage. Two hours or more, cast iron’s staying power is worth the wait.

Size matters as much as metal. A bowl that is too small for your seating area will feel underpowered whatever it is made of. Our fire pit size guide explains how to measure your space before you choose.

Durability and rust: what to expect outdoors

Any iron-based fire pit will meet moisture, and how it copes is where the two materials really part ways.

Cast iron is the tougher choice for a pit that lives outdoors. Ideal Home’s Amy Lockwood notes that a cast iron fire bowl is designed to rust if left outside all year, forming an attractive patina, and that it is easy to brush out once the embers have cooled. So surface rust is part of its look rather than a fault. Many owners like the aged, rustic finish it develops.

Steel is lighter, but it does best when it is looked after. The same guide says steel needs storing indoors to prolong its lifespan. If you have a shed or garage with space, that is simple enough. If you would rather leave your fire pit on the patio all year, that is a point in cast iron’s favour.

Whichever you choose, a few habits keep any metal fire pit in good shape:

1. Let it cool fully before you clear it out, then brush the ash out. Damp ash sitting in the bowl holds moisture against the metal.
2. Keep rain out where you can, with a lid or a cover, or by moving a lighter pit under cover.
3. Check the base and legs now and then for surface rust that is flaking rather than staining, and brush it back.
4. Store lighter steel pits indoors over winter if you can.

Weight and where it will sit

Weight cuts both ways. A heavy cast iron fire pit feels stable and is not going to be knocked over by a child or a gust of wind. Once placed, though, it is a job to relocate, so it suits a settled spot on a patio or paved area.

A lighter steel pit is the opposite. James Bentley of Charles Bentley says a compact metal pit is great for smaller patios or gardens and light enough to move around, as quoted in the same Ideal Home guide. That flexibility is handy if you want to bring it to the front of the garden in summer and tuck it away against the house in winter.

One safety point follows from this. Whichever you choose, it must stand steady. The fire safety advice from Mawddach and West Wales Fire and Rescue Service is to make sure your pit is steady to minimise the risk of toppling, and to avoid siting it on decking or near trees and structures. If your only flat spot is a deck, read our guide to placing a fire pit on decking first.

Fire pit or chiminea?

If you are weighing up cast iron, you may also be weighing up a chiminea, which is typically made from cast iron, clay or steel. The difference is in how the heat travels. James Bentley’s view in the Ideal Home guide is that chimineas tend to direct warmth forwards, so they suit smaller gatherings, while fire pits spread heat more evenly and can often accommodate a bigger group.

If that is the choice you are facing, our chiminea vs fire pit guide walks you through it in three questions. You can also compare the cast iron options in our chimeneas and heating range.

Can cast iron withstand fire?

Yes. Cast iron is a dense metal that takes high temperatures well, and fire bowls made from it are built for open fires. That is why a cast iron fire bowl can sit outside, take repeated fires and simply weather over the years, as described above.

The sensible precautions are the same as for any fire pit:

• Buy a pit designed for burning, with a bowl or firebasket, rather than adapting another item.
• Build up the fire gradually rather than piling on fuel straight away.
• Do not throw cold water onto a hot metal bowl. Use water, sand or a hose to put out the fire in the way your fire pit’s instructions recommend, and let the metal cool before handling it.
• Check the pit regularly for any hairline cracks or damage and follow the maker’s instructions.

Where to put it and how to use it safely

The material matters less than where and how you light it. UK fire services give consistent guidance. The Mawddach and West Wales fire service advice says to:

• make sure the fire pit is steady,
• avoid decking, trees and structures,
• check the weather and wind direction before lighting,
• keep a bucket of water, sand or a garden hose within reach.

The same page says never to use petrol or similar chemicals to start a fire, to use kiln-dried wood to reduce sparks and smoke, and never to burn painted, coated or pressure-treated wood, plastic, rubber or general waste, because these can release toxic chemicals.

Our fire pit safety guide covers recommended distances from the house and fences. If your garden includes a pool area, this piece on poolside fire pit setups is useful for planning the layout of a fire feature beside water.

Smoke control areas

Many UK towns and cities are smoke control areas. Government guidance says you can still use outdoor barbecues, chimineas, fireplaces and pizza ovens there, and garden bonfires are allowed subject to the bonfire rules, but releasing smoke from a chimney in such an area can attract a penalty of up to £300 in England, as set out on GOV.UK.

Defra’s practical guide to smoke control areas (January 2024) gives the fine as between £175 and £300, and adds that you must not buy an unauthorised fuel for use in a smoke control area unless it is for an exempt appliance, with a fine of up to £1,000. Your local council can tell you whether your address is covered. For what to burn, see our fire pit fuel guide, and for ways to cut smoke see our explainer on smokeless fire pits.

How to choose: five questions

Run through these and the answer usually becomes clear.

1. Will it stay outside all year? If yes, cast iron is the better fit. If you can store it in a shed, steel is fine.
2. How long do you sit out? Short evenings suit steel’s quick warm-up. Long ones suit cast iron’s heat retention.
3. Will you move it? Regular moving points to a lighter steel pit. A fixed spot suits cast iron.
4. How many people? Larger groups benefit from an open fire pit that spreads heat evenly. Smaller groups can be well served by a chiminea.
5. What look do you want? Cast iron brings a rustic, weathered character. Steel gives a lighter, more contemporary feel.

Our view

Most people ask us which metal is “better”, and the honest answer is that it depends on the evening you imagine. If you picture a long dinner with the fire glowing down and a pit that sits on the patio from spring to winter, cast iron gives you that weight, that steadiness and that slow, reassuring warmth.

If you picture a quick fire after work, something you can carry to a different corner of the garden, steel is a lovely, practical choice and warms up fast.

Whichever you pick, give it a firm, level, non-combustible spot, keep water or sand nearby and brush it out once it has cooled. Those few habits matter more than the metal. We would rather you choose the one you will enjoy using every week.

Peter

Find your fire pit or chiminea

If cast iron appeals, our chimeneas and heating range includes cast iron designs such as the Gardeco Toledo Cast Iron Chimenea in large black and the large bronze version. Orders over £70 come with free delivery, next-day delivery options are available, and you can return items within 14 days.

If you are building a whole outdoor space, you can browse outdoor dining and garden furniture to go with it.

FAQ

Is cast iron or steel better for a fire pit?

Neither wins on every count. Cast iron is heavier and more durable, heats more slowly and holds heat longer, so it suits a pit left outdoors. Steel heats quickly and is lighter, but is best stored indoors to prolong its life.

Will a cast iron fire pit rust?

If it is left outside all year, yes, on the surface. A cast iron fire bowl is designed to rust gently and form a patina, and the ash is easy to brush out once the embers have cooled.

Can I put a fire pit on decking?

Fire services advise avoiding decking, as well as trees and structures, when siting a fire pit. If decking is all you have, follow the precautions in our decking fire pit guide before lighting anything.

Can I use a fire pit in a smoke control area?

Government guidance says outdoor barbecues, chimineas and fireplaces can be used in a smoke control area, and garden bonfires are allowed subject to bonfire rules. Use suitable fuel and check with your local council for your address.

Sources

• Best fire pits, Ideal Home
• Firepit Safety Advice, Mawddach and West Wales Fire and Rescue Service
• Smoke control areas: the rules, GOV.UK
• Smoke Control Areas: a practical guide, Defra, January 2024

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• Fire Pit Types for UK Gardens: Five Fuels and Where Each Works
• 3 Questions That Settle Chiminea vs Fire Pit for UK Gardens
• Measure First: 24 to 36 inches Fire Pits That Actually Warm UK Gardens
• 3 Metre Rule: Fire Pit Safety and Smart Buying for UK Gardens