Rock Solid Results: Must-Know Tips for Choosing for Sauna Stones
10/17/2025
By Mike Lawson
When building or upgrading your sauna, it’s easy to focus on the room layout, the wood species, or which heater looks and functions best. But there’s one important detail that’s often overlooked: sauna rocks.
When it comes to saunas, not all rocks are the same. The type of rocks you use in your heater can have a big impact on how it performs, the quality of your steam, and even the safety of your setup. Here are five key things to know when choosing sauna rocks - and how to get the most out of them.
1. Choose Stones That Can Handle the Heat
Sauna rocks have to endure intense, repeated heating and cooling cycles without breaking down. Your best choice? Dense volcanic rocks like peridotite or diabase. These stones are specifically selected to withstand high temperatures and hold heat efficiently.
Avoid using river rocks or soft, porous stones - they can crack, crumble, or even damage your heater over time. Always choose sauna-specific rocks that are built for the job.
2. Mix Up the Sizes
The placement of your sauna rocks affects how well your heater performs. A mix of sizes is ideal:
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Larger stones go at the bottom to provide a stable base.
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Smaller stones fill in some of the gaps to improve airflow. Remember – a heater does need some air gaps to function properly!
This helps distribute heat evenly and creates smoother, more satisfying steam. A properly stacked heater makes a noticeable difference in your sauna session.
3. Only Use Clean, Sauna-Specific Stones
Not all rocks are safe to use in a sauna. Decorative stones or ones you pick up from your backyard may contain chemicals, moisture, or contaminants that can release harmful fumes when heated.
Always use rocks sold specifically for saunas, and make sure they’re from a trustworthy manufacturer. They’re not only safer, but they’ll last longer and perform better. If you're unsure where to find them, your sauna dealer can help you choose the best rocks for your setup.
4. Know How Much You Need
You might be wondering: How many rocks do I actually need? The answer depends on your sauna’s size and your heater’s specifications. Most home saunas use anywhere from 50 to 100 pounds of rock.
Check your heater’s manual or ask your dealer to help calculate the right amount. Using too few or too many stones can reduce heating efficiency and steam output.
5. Replace Worn-Out Stones Regularly
Even heavy-duty sauna rocks don’t last forever! Over time, they break down from repeated heating and cooling. That’s why it’s important to inspect them regularly for cracks, crumbling, or signs of mold.
In general, rocks should be replaced every 2 to 5 years, depending on how often you use your sauna. Refreshing your stones ensures optimal heat transfer, improves steam quality, and protects your heater from unnecessary strain.
The Takeaway:
Sauna rocks may seem like a small detail, but they’re a big part of what makes a sauna feel amazing. Choosing the right ones - and maintaining them over time - can make all the difference in heat, steam, and overall comfort.
If you’re ever unsure about what stones to use, how to stack them, or how many you need, your local sauna expert is there to help. They don’t just sell rooms – they specialize in helping you get the most out of your sauna, down to the smallest pebble!
