Why did my pizza stone crack?

Thermal shock: the main cause

Stone expands as it heats. If the top surface is at 450°C and the underside is much cooler, or one corner sits right next to the flame while the opposite corner is still cold, the stone is pulled in two directions. When that stress gets too high, it cracks. This is thermal shock, and it is behind most cracked stones.

Portable gas and wood ovens are harder on stones than a kitchen oven because they heat fast and the flame sits close to the back edge. A cold stone that goes straight onto full flame has a big temperature gap between the back and the front. Starting on a lower flame for the first few minutes and then turning up gives the whole slab time to warm more evenly.

Moisture trapped in the stone

Cordierite is porous. If a stone has been washed with water, left out in the rain or stored in a damp shed, water soaks in. Heat it quickly and that water turns to steam inside the stone, which can split it. This is a common reason for a crack on the first bake of the spring.

Never soak a pizza stone or put it in the dishwasher. Scrape it dry and brush it instead. If it does get wet, let it dry fully at room temperature for a day or two, then heat it slowly. Our guide on how to clean a pizza stone covers safe cleaning, and storing a pizza oven in winter explains how to keep the stone dry between seasons.

Cold, wet or heavy food on a hot stone

Dough straight from the fridge, frozen pizza, or a pool of water or sauce on a very hot stone cools one spot fast. The rest of the stone stays hot, and the stress can crack it. Very heavily loaded pizzas and liquid spills do the same.

Let dough balls come up to room temperature before stretching, keep wet toppings away from the edge, and never pour water or oil onto a hot stone. If you cook frozen pizza, use a lower temperature or a tray, as the maker allows. Do not cool a hot stone with water or move it outside into cold air while it is hot.

• Heat slowly from cold, especially after storage.
• Keep the stone dry, never soak it.
• Bring dough to room temperature first.
• Wipe up spills only once the stone is cool.
• Let the stone cool inside the oven.

Is a cracked stone still safe to use?

Many cooks carry on with a stone that has a single hairline crack. Once the crack has happened, the stress that caused it has been released, and a stone that still sits flat, does not wobble and has no loose fragments often bakes much as before. Keep the halves pushed tightly together so the peel cannot catch on the gap.

Replace it if it has broken into several pieces, if the pieces rock or sit at different heights, if chunks are flaking off, or if the crack keeps widening. An uneven floor makes launching and turning harder, and loose fragments can fall into a burner area. Makers generally sell replacement stones for their own ovens, so check the manual or the maker's site for the right part and size rather than buying a generic one that may not fit.

Note:Always let the stone cool fully inside the oven before handling it. A stone can stay hot enough to burn for a long time after the flame is off. Use heat-proof gloves.

Stone, steel or a better oven

If you mainly bake in a kitchen oven, a steel will not crack and conducts heat quickly, though it is heavy. Our pizza stone vs pizza steel article explains the trade off. For outdoor ovens, the stone is part of the design, so stick with the maker's replacement.

If cracking keeps happening, look at how your oven heats. Ovens with a burner across the back and side, or a thicker stone, tend to heat the floor more evenly. Our best gas pizza oven and best outdoor pizza oven guides list current options, and you can browse more advice in peels and stones.

See the best gas pizza ovens →

Frequently asked questions

Why did my pizza stone crack in the oven? Usually thermal shock: a damp stone heated fast, cold food on a hot stone, or one edge much hotter than the rest. Heat slowly and keep the stone dry.

Can I still use a cracked pizza stone? Often yes, if it has a clean crack, sits flat and does not move. Replace it if pieces rock, flake or the crack keeps growing.

Where do I get a replacement stone for an Ooni or Gozney Roccbox? Check the maker's website or manual for the correct replacement part. Sizes and thickness differ between models, so a generic stone may not fit or heat the same way.

Should I wash a pizza stone with water? No. Scrape and brush it when cool. Water soaks in and can cause a crack the next time the stone is heated.