Pick the correct size of sauna. First you should consider how many people will use the sauna at the same time? Will this be only for you, or for a large group? Heating unoccupied space is an unnecessary expense. Ceiling heights should never be bigger than 7 as this is wasted air space.
Do you prefer an outdoor or indoor sauna? If you are looking at an outdoor sauna then pay careful attention to the quality. It should have a good roof and be made of thick material. Choose a heater that is larger than an indoor sauna so that it can overcome the outdoor weather conditions.
When it comes to the door, think about what you want before you buy. A glass panel will make the room feel less confining, but you will sacrifice privacy. Will you want that privacy? An insulated door is a good idea for an outdoor unit, but not needed for a sauna in the house.
Infrared saunas are becoming popular, but I suggest before you buy you try it out as many sauna enthusiasts do not consider this a proper sauna. If you want high humidity and higher temperatures then a Finnish style sauna heater should be chosen. Companies like ModernSpa also make hybrid or combo rooms that have both types of heaters in them.
The type of wood is important as it will ultimately determine the life of your home sauna. Cedar has always been considered the best but comes with a higher price. Saunas made from cedar last a long time, and don't heat up like other woods. Avoid woods with knots. That is dangerous.
All sauna rooms need to breath, circulating the air is important. A sauna should draw in fresh air and vent out the heated air. This vented air is hot and can be humid so you need to have an exhaust system that goes to the outside of your house. So you need install a exhaust fan to get rid of the heated air.
Sauna rooms come in two forms. One is a material kit that is framed into and existing room. The other is a modular sauna that comes with pre-assembled walls. These are stand-alone sauna rooms that assemble quickly but have less flexibility since the dimensions are fixed.
Look at quality as the number one factor. Go with the cedar. Investing in a quality sauna room will mean your sauna will last 25 or more years and will add to the value of your home. Most important point is that investing a high quality sauna room means safe spa enjoyment.