Sauna Rocks: Everything You Need to Know

Stepping into a sauna is like stepping into another world - a world of heat, steam, and relaxation. An essential part of the sauna experience is the pile of hot rocks, known as the sauna rocks or Kiuas, that help create the dry Finnish sauna atmosphere.

But what exactly are sauna rocks? What type of rock should you use, and why does it matter? Getting the right rocks is imperative for safety and getting the most out of your sauna session.

In this guide to sauna rocks, we will cover everything you need to know, including:

  • What are sauna rocks, and why are they important
  • Types of sauna rocks to use
  • Sauna rock alternatives
  • How to use and maintain your rocks properly
  • Sauna rock safety tips
  • Common mistakes to avoid

Whether you're designing a new sauna or maintaining an existing one, this guide will provide all the essential rock knowledge you need for a safe and soothing sweat. 


sauna rocks

What are Sauna Rocks?

Sauna rocks are specially selected stones placed in a sauna heater, where they absorb and store heat from the heating elements, whether it's an electric sauna heater or a wood-burning sauna stove. These rocks are not just any ordinary stones; they are chosen for their ability to withstand the extreme temperatures and rapid temperature changes found in saunas.

Why Use Sauna Rocks?

The primary purpose of sauna rocks is to retain heat and create steam when water is poured over them. This steam increases the room's humidity, making more heat feel more intense. The high heat capacity of the rocks ensures they stay hot for longer periods, providing a consistent sauna experience. Sauna rocks also contribute to good ventilation within the sauna room, helping to circulate the hot air and steam evenly.


sauna rocks

Aromatherapy and Sauna Rocks

Aromatherapy in the sauna, especially when combined with sauna rocks, can turn a regular sauna session into an even more soothing and therapeutic experience. When you add essential oils to sauna rocks, the heat helps to spread the lovely scents throughout the room, making the air smell wonderful and bringing various potential sauna health benefits.

How to Use Aromatherapy with Sauna Rocks

  • Choosing Oils: Pick essential oils based on the mood or health benefit you're aiming for. For relaxation, lavender or chamomile are great choices. For a refreshing and invigorating effect, try eucalyptus, peppermint, or citrus oils.
  • Application: Instead of putting essential oils directly on the hot rocks, which can cause them to burn off too quickly or damage the rocks, mix a few drops of your chosen oil with water in a sauna bucket. Then, gently ladle this scented water onto the rocks. This method helps release the essential oil scents slowly and safely.
  • Intensity: Start with just a few drops of essential oil. The heat will intensify the fragrance, and a little goes a long way. You can always add more if you prefer a stronger aroma.

Potential Benefits of Aromatherapy in the Sauna

  • Relaxation: Certain scents like lavender can help calm the mind and reduce stress, making your sauna session an even more relaxing escape.
  • Respiratory Relief: Eucalyptus and peppermint can potentially help clear nasal passages and improve breathing, which is especially beneficial in the warm, steamy environment of a sauna.
  • Mood Enhancement: Citrus and floral scents can potentially lift your spirits and improve your mood, making your sauna time a more uplifting experience.

Incorporating aromatherapy into your sauna sessions with more rocks can enhance the potential physical and emotional benefits of your sauna experience, creating a spa-like atmosphere right in your own home.


sauna rocks

What Size Sauna Rocks Are Best?

The size of the sauna rocks plays a significant role in the efficiency of your sauna. Rocks with a good shape and size create more surface area, allowing for better heat retention and distribution. Generally, rocks ranging from 2 to 6 inches in diameter are considered ideal as they provide a balance between thermal mass and surface area, facilitating efficient heat storage and steam production.

Types of Sauna Rocks

sauna rocks

Igneous Rocks

Igneous rocks, like basalt and granite, are the most common types of sauna rocks due to their durability and ability to withstand high temperatures without cracking. These rocks have a high thermal mass, making them perfect for retaining heat.


Granite is a popular choice for sauna rocks because of its smooth surface and resistance to thermal shock. This type of rock retains heat well and doesn't crack or break easily, making it a durable option for sauna heaters.


Basalt rocks, with their fine-grained texture and high density, are excellent at holding heat. They heat up quickly and release steam evenly when water is poured over them, creating a gentle and relaxing sauna experience.


sauna rocks

How Much Water Should I Pour on the Sauna Rocks?

The amount of water you pour on the sauna rocks can significantly affect the sauna's humidity and temperature. A little water goes a long way in creating steam. Start by pouring room temperature water gradually, using a sauna bucket, and observe how the steam affects the sauna's climate. Adding more water increases the humidity and heat sensation, but be cautious not to overdo it, as too much steam can make the air uncomfortably hot and damp.

Pouring cold water on the hot rocks can create an exhilarating experience, as it produces a burst of steam that raises the temperature momentarily. However, it's essential to do this sparingly to avoid damaging the rocks or creating excessive steam that could make the sauna experience less comfortable.

Sauna Rock Alternatives

While traditional igneous rocks like granite and basalt are the go-to choices for sauna rocks, there are alternatives for those looking to experiment or adapt to specific needs.


sauna rocks

Ceramic Stones

Ceramic stones are a modern alternative, designed to withstand high temperatures and rapid heating cycles. They are known for their smooth surface and uniform shape, which can provide a consistent and controlled heating experience. Ceramic stones also tend to have a lower thermal mass compared to traditional sauna rocks, which means they heat up and cool down more quickly, making them suitable for saunas that aren't used as frequently.

Artificial Heat-Resistant Stones

There are specially engineered, heat-resistant stones made from materials that can mimic the heat retention and distribution properties of natural igneous rocks. These stones are often used in electric sauna heaters and can be a good option for those who prefer a more uniform look or have specific aesthetic preferences for their sauna room.

Glass Rocks

Glass rocks, often used for decorative purposes in gas fireplaces, have found their way into some contemporary saunas. While they don't retain heat as well as traditional sauna stones, glass rocks can withstand the sauna's high temperatures and provide an interesting visual element. They are best used in conjunction with a traditional heater to ensure the sauna reaches the desired temperatures.

Lava Stones

Lava stones, while still a type of igneous rock, offer a different aesthetic and physical texture compared to granite or basalt. They have a porous surface, which can help to create a more intense steam when water is poured over them. Lava stones can be a great choice for those looking to add a natural, rugged look to their sauna.

When considering alternatives to traditional sauna rocks, it's imperative to account for their heat capacity, durability, and impact on the sauna's humidity and temperature. Always ensure that the alternative materials are safe to use in high-heat environments and won't release any harmful substances when heated.


Related To: How to Control the Temperature of a Sauna


sauna rocks

How To Use And Maintain Your Sauna Rocks Properly

Proper use and maintenance of your sauna rocks are important for ensuring a safe, enjoyable, and long-lasting sauna experience. Here are some guidelines to help you care for your sauna rocks:

Using Your Sauna Rocks

  1. Layering: When placing rocks in your sauna heater, ensure they're layered loosely to allow air to circulate. This ensures efficient heating and allows the rocks to retain heat more effectively.
  2. Heating Up: Allow your sauna rocks to heat up gradually with the sauna. This reduces the risk of thermal shock, which can cause rocks to crack or break.
  3. Water Pouring: Pour water gently over the rocks to create steam. Use a wooden ladle and sauna bucket for traditional saunas, and ensure the amount of water is moderate to avoid cooling the rocks too quickly or creating excessive steam.

sauna rocks

Maintaining Your Sauna Rocks

  1. Cleaning: Regularly inspect and clean your sauna rocks. Remove them from the heater once they're cool and wash them to remove any accumulated dirt or debris. This is important for preventing unpleasant odors and ensuring the rocks can efficiently absorb and radiate heat.
  2. Rotation: Periodically rotate your sauna rocks to ensure even wear and exposure to heat. This helps in prolonging their lifespan and maintaining their heat retention capabilities.
  3. Replacement: Over time, sauna rocks can degrade, losing their ability to retain heat effectively. Inspect your rocks periodically for signs of wear, such as crumbling or cracking. It's recommended to replace your sauna rocks every few years, or more frequently if you use your sauna often.
  4. Avoid Chemicals: Never use harsh chemicals or detergents to clean your sauna rocks, as they can release harmful fumes when heated. Stick to plain water, and if necessary, a mild, natural cleaning solution.

Ensuring Good Ventilation

Good ventilation in your sauna is essential for maintaining air quality and ensuring the proper operation of your sauna heater and rocks. Make sure your sauna has an adequate ventilation system to allow fresh air in and exhaust stale air, along with any impurities released from the heated rocks.


sauna rocks

Sauna Rock and Sauna Heater Safety Tips

Ensuring safety while using sauna rocks is paramount to prevent accidents and injuries. Here are some essential safety tips to keep in mind:

Handling Hot Rocks

Never Touch Hot Rocks: Always use a ladle to pour water onto the rocks. Direct contact with hot sauna rocks can lead to severe burns.

Use Proper Tools: Employ a wooden ladle and bucket to pour water onto the rocks to minimize the risk of burns and to control the amount of water accurately.

Water Pouring

Gradual Pouring: Pour water slowly and in small amounts to avoid sudden bursts of steam that could cause burns or discomfort.

Avoid Overheating: Excessive water can cool the rocks too rapidly, leading to potential cracking or damage to the rocks and the heater.

Rock Placement

Stable Arrangement: Ensure the rocks are securely placed within the heater to prevent them from falling or shifting, which could cause injury or damage to the sauna.

Allow for Airflow: Arrange the rocks loosely enough to allow for proper airflow, which facilitates efficient heating and reduces the risk of overheating or fire hazards.


sauna rocks

Sauna Stones Maintenance and Inspection

Regular Checks: Periodically inspect your sauna rocks for signs of wear, such as cracks or crumbling. Damaged rocks should be replaced immediately to avoid the risk of them breaking apart and causing injury.

Cleaning Precautions: When cleaning sauna rocks, ensure they have cooled down completely to prevent thermal shock and potential injury.

General Sauna Safety

Ventilation: Maintain good ventilation within the sauna room to prevent excessive heat buildup and to ensure a supply of fresh air, enhancing the safety and comfort of your sauna experience.

Emergency Measures: Be aware of how to quickly turn off the sauna heater in case of an emergency and ensure that the sauna space has easy access in and out.


sauna rocks

Common Mistakes To Avoid

Ensuring a safe and enjoyable sauna experience involves being aware of and avoiding common mistakes related to sauna rock usage and sauna practices in general.

Here are some key points to consider:

Overcrowding the Heater

Too Many Rocks: Filling the heater with too many rocks can restrict airflow, leading to inefficient heating and potentially overheating the electric elements or wood in a sauna stove.

Using the Wrong Type of Rocks

Non-Igneous Rocks: Avoid using rocks that are not meant for high-heat environments, such as sedimentary rocks like sandstone, which can crack or explode when heated.

Improper Water Usage

Excessive Water: Pouring too much water at once can lead to a rapid temperature rise, creating uncomfortably hot steam that could burn the skin.

Cold Water: Using cold water can cause thermal shock to the rocks, reducing their lifespan and potentially causing them to crack.


sauna rocks

Neglecting Maintenance

Ignoring Wear and Tear: Not replacing worn or cracked rocks can lead to inefficient heating and even damage to the sauna heater.

Poor Ventilation: Failing to maintain good ventilation can lead to poor air quality and excessive humidity, detracting from the sauna experience and potentially damaging the sauna structure.

Lack of Safety Precautions

Leaving the Sauna Unattended: Never leave a sauna heater on without supervision, especially in wood-burning saunas, to prevent the risk of fire.

Skipping Pre-Use Checks: Always inspect the sauna and its components, including rocks and heaters, before use to ensure everything is in safe working order.

Overheating the Sauna Room

Too High Temperatures: Setting the sauna temperature too high can lead to health risks, including overheating and dehydration. Always keep the sauna at a comfortable temperature, and listen to your body to avoid staying in the sauna for too long.


sauna rocks

In Summary

Sauna rocks are an integral and often overlooked part of the sauna experience. As we've explored, not just any rocks will do. Getting the right type of sauna stones and caring for them properly can make a whole lot of difference.

By understanding sizing, placement, maintenance, and safety precautions for sauna rocks, you can enhance your sauna significantly. Pay special attention to ventilation, gradual water pouring, and replacing worn rocks.

The foundation of a quality sauna session lies in seemingly mundane details - the layout, the wood, and yes, the rocks. But when done right, these details add up to something truly magical - a haven for cleansing, detoxing, and quieting the mind. Sauna on!

Item is added to cart