Harvia Sauna Heater Stones (Small 5 - 10cm) 20kg – Non-Gaseous Explosion Safe

Harvia Olivine Diabase Sauna Stones 5–10 cm – 20 kg

Best For: Anyone fitting or maintaining an outdoor sauna with an electric or wood-burning heater. The go-to stone for first-time buyers and experienced bathers alike — trusted by Harvia and used in saunas worldwide.

Harvia Olivine Diabase sauna stones are the most widely used sauna stone in the world, and for good reason. Mined in western Finland from dense, sub-volcanic rock, these traditional dark grey stones absorb heat rapidly, hold it for longer, and release it evenly — producing the consistent, satisfying steam that defines a genuine Finnish sauna. The angular, split-face surface gives water more contact area, generating full, smooth löyly with every pour. Each 20 kg box contains stones sized 5–10 cm, the recommended size for electric heaters and for the top layer of wood-burning heaters.

Key Features:

• Stone type: Olivine diabase — traditional Finnish sauna stone
• Size: 5–10 cm (recommended for electric heaters)
• Box weight: 20 kg
• Colour: Dark grey
• Split-face surface for maximum heat release and steam generation
• Easy to stack with good air circulation between stones
• Excellent heat storage capacity, durability and thermal conductivity
• Safe and free from harmful chemicals
• Mined in Finland
• Compatible with all Harvia electric and wood-burning heaters

How To Use Rinse stones before loading to remove dust. Stack loosely in the heater basket so stones support each other without resting their full weight on the heating elements. Ensure good gaps for airflow throughout. After loading, heat the sauna and throw a few ladles of water over the stones to disperse any natural stone scent on the first session. Inspect stones annually and replace any that are cracked or crumbling.

The Result Dense, even heat with rich, smooth steam every session. Olivine diabase maintains stable performance over years of regular use, making it the most reliable and cost-effective stone choice for any outdoor sauna.