If your sauna makes cracking, popping, or ticking sounds as it heats up, you can relax — this is completely normal. Here’s what’s actually happening.

Cracking and Ticking: Thermal Expansion

Wood expands slightly as it warms and contracts as it cools. Every time your sauna goes through a heat cycle, the hemlock panels, frame, and bench are all moving in small but real ways in response to the rising temperature. When adjacent pieces of wood shift against each other or against metal hardware, the result is a cracking or ticking sound.

This is the same phenomenon you hear in hardwood floors, wood-framed houses on cold nights, or furniture near a heating vent. It’s the material doing exactly what it’s supposed to do. The sounds tend to be most noticeable during the first heat cycle of the day and will quiet down once the sauna reaches a stable temperature.

Quiet Popping from the Walls: FIR Temperature Switches

You may also hear occasional soft popping or clicking sounds coming from inside the walls. This is the far infrared heater panels’ built-in thermal cutoff switches activating.

These switches are a safety feature. As the panels reach high temperatures, the switches momentarily interrupt the circuit to prevent overheating, then reset themselves once the temperature drops slightly. The cycle repeats at a low frequency throughout your session — the quiet pop you hear is the switch toggling. It’s a sign the safety systems are doing their job.

Note: If you hear sounds that are loud, sharp, or accompanied by a burning smell, smoke, or anything unusual — that is not normal. Unplug the sauna and contact Plunge Support before using it again.