Seven feet. That's how tall you want your ceiling height in a traditional sauna. The ceiling height is one of the most important details that is commonly overlooked. Many people want their sauna to have tall ceilings to achieve a certain look for the facility, however this is a mistake.
Hot air rises. That means all the work your heater is doing to get your room to tempurature is going to waste if your sauna's ceiling is too tall. In a standard sauna there are two benches, upper and lower. The upper bench is where most of the heat is. The lower bench is for if you need to cool down a little, or for children who want to be in a sauna. If your ceiling is taller then seven feet the best heat is rising past where you can feel it.
This is one of the most common reasons why your sauna isn't heating up. If you are running into this problem start by measuring your ceiling height.