Concrete, GFRC, Copper, Corten, Steel and Stone Compared

The material of a fire feature decides how it looks on day one, how it looks in year five, and how much of your weekend it asks for. Cast concrete and GFRC hold their color and shape and suit almost any setting. Carbon steel and copper change over time, and that change is the point. Stainless steel stays bright with cleaning. Natural stone is heavy, unique and very calm. Here is how each one behaves outdoors, drawn from what the makers themselves publish.

Concrete and GFRC: the backbone of the collection

Most of the fire tables and bowls we sell are cast concrete, and most of those are GFRC, short for glass fiber reinforced concrete. The precast industry's guide specification describes GFRC as a portland cement and silica sand mix reinforced with alkali resistant glass fibers, sprayed or laid into molds starting with a thin mist coat. American Fyre Designs describes the result in plain terms: its GFRC gets its strength from alkali resistant glass fiber and acrylic polymer blended into the concrete. AFD also notes that its finished shells are typically half an inch to three quarters of an inch thick and weigh a fraction of what traditional precast concrete would.

So GFRC is not the opposite of precast concrete. It is a thinner, fiber reinforced way of casting it. Slick Rock Concrete, for example, calls its bowls GFRC made from a high performance concrete blend in its technical data, and calls them precast in its care guide. Prism Hardscapes lists its fire and water bowls as GFRC.

Lighter does not mean light. Prism lists its Embarcadero 60 fire table at 350 pounds. The AFD Legend Long is 320 pounds. At the small end, Slick Rock's 22 inch bowls are about 50 pounds. Plan delivery and placement with the weight on each product page in mind.

How color and texture work in concrete

Color is built into the mix, stained on the surface, or both. Slick Rock uses integral color followed by a water based, semi transparent stain, then a sealer. Every maker we carry warns that handmade concrete varies. AFD says its finishes are subject to slight texture and color variation. Slick Rock says no exact match is guaranteed between pieces or to printed charts. Elementi puts a figure on it: color and texture variation up to 15 percent, and small surface holes from casting, are a normal trait of cast concrete. Our guide to choosing a concrete finish color lists the named colors by brand.

Living with concrete

Concrete asks for little, but it asks for the right things. Slick Rock says chemical cleaners should never be used on its concrete, and rules out pressure washers and other mechanical cleaning. AFD recommends a mild soap and water wash. Resealing schedules differ by maker and even by manual, so follow the care guide for your specific model. Slick Rock also cautions against rubberized, plastic or other nonbreathable coverings, which can cause the sealer and stain to delaminate. Fine hairline cracks are part of the material: Slick Rock describes small non-structural cracks as common and inherent in precast concrete, and Fire by Design's warranty excludes stress cracks and surface crazing.

Porcelain tops: the look of marble without the upkeep

Elementi's Plus line pairs a metal frame with a marble porcelain top. It is not natural marble, and that is the appeal: a polished stone look in black or white. The Carrara and Bianco are the white versions, and the Varna and Sofia the black. They suit modern and coastal schemes where cast concrete would feel too heavy.

Carbon steel: art that changes with every fire

Fire Pit Art builds its wood-burning pits by hand from quarter inch mild carbon steel. The pieces arrive with a dusty, rust colored iron oxide patina. After the first fire, Fire Pit Art says, the patina starts to mature and darkens toward a deep mahogany. Gas fires mature it more slowly than wood fires.

That living finish comes with a few rules from the maker. Do not tarp the pit while it matures, because the tarp stops the oxidation that needs air. Keep wet leaves and debris off it. Never set a wood-burning fire pit on a wood surface. Fire Pit Art warrants its carbon steel pits for 10 years, but offers no warranty on the iron oxide patina itself, and excludes discoloration or damage to a patio or deck. In our experience, the practical answer is to place a steel pit on gravel, stone or a surface you are happy to see weather along with it. See how the finish develops in our guide to how steel fire pits patina.

Stainless steel: bright, structural and low drama

Stainless steel keeps its metallic look rather than rusting to a patina. Fire Pit Art makes its Bella Vita in quarter inch 304 stainless steel and its warranty page covers stainless pits for 100 years for structural integrity. The Bella Vita pages word that guarantee differently, so check the paperwork that ships with your pit. Stainless still needs attention, though. Fire Pit Art notes that stainless steel requires periodic cleaning to keep its finish, and Elementi recommends cleaning stainless surfaces at least every two weeks in salt air. Elementi, for example, builds its burner rings and pans from 304 stainless steel.

Weathering steel (corten): a rusted look that protects itself

Weathering steel, often sold under the name corten, is a low alloy steel with small amounts of chromium, copper and nickel. Steel construction references explain that it forms a protective rust patina through repeated wetting and drying, usually reaching a dark brown within two to five years. Two cautions matter for outdoor rooms. Early rust runoff can stain pavers and paths, and architects plan drainage around it. And the protective patina struggles where the steel stays wet or where salt spray keeps the surface damp, so the same references caution against it where salt spray reaches the steel.

Copper: from penny bright to blue green

Copper starts warm and metallic. Its famous blue green patina takes years to form. The Copper Development Association says natural blue green patina may take five to seven years in coastal or industrial air, longer in rural areas, and may never develop in some climates. Fire Pit Art's cleaning advice for steel and copper pits is hot soapy water, a soft cloth, a rinse, and drying immediately.

Natural stone: one of a kind and very heavy

Waterstone Fire Tables cuts its tops from gneiss, a metamorphic granite, taken from glacial boulders hand selected in Minnesota. Each slab has its own color banding, so the table you buy is the only one like it. Stone is also the heaviest option: Waterstone lists its tables from 150 pounds to 550 for a large table, and its fire rocks, where the boulder itself is the base, generally between 1,000 and 3,000 pounds. Waterstone says its design sends the heat up rather than into the stone. The maker publishes no sealing or care schedule, so ask our team before applying any product to the stone. Browse the slabs in our stone collection.

The materials side by side

Choosing by setting

Near the ocean, concrete and stone are the calmer choices, since salt air shortens the patience of most metals and Fire Pit Art excludes saltwater environments from its warranty. On a wood deck, a gas fire table in concrete or porcelain is the usual answer, and wood-burning steel pits should not sit on wood at all. In freezing climates, follow your manual closely. Elementi's manual, for example, recommends storing its tables indoors in winter because extreme cold can crack the top, while its FAQ says a covered table can stay outside, so go by the paperwork for your model. Around a pool, confirm with the manufacturer's documents which items are suited to a pool deck before you choose.

For style, the material usually decides half the look before you pick a color. Our guide to five design styles shows how each material fits a modern, organic, Old World, desert or coastal scheme.

These pieces show each material at its best.

Common questions

Is GFRC the same as concrete?

GFRC is concrete, cast in a particular way. It is a cement and sand mix reinforced with alkali resistant glass fibers and usually polymers, sprayed or laid into molds in thin layers. American Fyre Designs says its finished GFRC is typically half an inch to three quarters of an inch thick and a fraction of the weight of traditional precast concrete. That thin, reinforced shell is why large GFRC tables can be moved and shipped at all.

Will a steel fire pit stain my patio?

It may. Carbon steel pits carry a rust patina, and rusty water may mark pale stone or concrete, especially early on. Fire Pit Art's warranty excludes discoloration or damage to a patio or deck surface. We suggest placing a steel pit on gravel, dark stone or another surface you are comfortable seeing weather, and never setting a wood-burning pit on a wood deck, which Fire Pit Art prohibits.

Do concrete fire tables crack?

Fine hairline cracks can appear in any cast concrete and are usually cosmetic. Slick Rock describes small non-structural cracks as common and inherent in precast concrete, and Fire by Design's warranty excludes stress cracks and surface crazing. Good drainage, a breathable cover and following your model's sealing and winter guidance all help. Structural defects are a warranty matter, so check the paperwork that ships with your unit.

Which fire feature material is best near the ocean?

Cast concrete and natural stone are the calmest choices near salt water. Metals need more care there: Elementi recommends cleaning stainless steel at least every two weeks in salt air, steel references say salt spray works against the weathering steel patina, and Fire Pit Art excludes saltwater environments from its warranty. Choose a light or softly colored concrete finish if you want the coastal look.

Sources

1. Precast/Prestressed Concrete Institute, Guide Specification for Glass Fiber Reinforced Concrete, Sections 2.3 and 2.9
2. American Fyre Designs, GFRC
3. American Fyre Designs, 2026 Product Catalog, page 4
4. American Fyre Designs, Available Finishes and Textures
5. American Fyre Designs, Fire Bowl Installation and Owner's Manual L-H2-064, cleaning, page 42
6. American Fyre Designs, Fire Tables Installation and Owner's Manual L-H2-058, Table 1
7. Slick Rock Concrete, Tech Data
8. Slick Rock Concrete, Proper Care and Maintenance
9. Slick Rock Concrete, Resources, product weight table
10. Slick Rock Concrete, RidgeLine Square 22 drawing, material and finish notes
11. Prism Hardscapes, Embarcadero 60 Installation, Operation and Maintenance Manual, page 3
12. Prism Hardscapes, Fire and Water Bowls Instructions
13. Fire by Design, Limited Warranty
14. Elementi, Warranty and Return Policy
15. Elementi, Carrara OFP121BW product page, materials
16. Elementi, Manhattan OFG103NG Owner's Manual, care and winter storage, page 15
17. Fire Pit Art, The Patina Process
18. Fire Pit Art, The Rings of Warmth: Saturn, patina on gas and wood pits
19. Fire Pit Art, Warranty
20. Fire Pit Art, Delivery Method, wood surface warning
21. Fire Pit Art, The Ageless Beauty of a Natural Patina Steel Fire Pit
22. Fire Pit Art, How To Properly Clean Any Cast Iron, Steel, Brick, or Copper Fire Pits
23. Fire Pit Art, Bella Vita 34
24. SteelConstruction.info, Weathering steel
25. New Steel Construction (BCSA and SCI), Atmospheric corrosivity classifications for weathering steel
26. Metal Architecture, Weathering Steels Offer Distinct Elements of Design
27. Copper Development Association, How to Apply Statuary and Patina Finishes (A1081), page 5
28. Waterstone Fire Tables, FAQ
29. Waterstone Fire Tables, home page