What is the difference between Horizontal and Vertical Tongue & Groove?
These days, most traditional saunas are installed with horizontal Tongue & Groove as a standard. This method is the easiest way to install cedar boards, and provides a better moisture seal versus vertical T&G. Horizontal boards are installed with the tongue facing up, meaning that water would have to fight gravity to get behind the board. Vertical T&G can have moisture seep through the seams. There can be a cost component as well, as Vertical T&G will require all boards to be 7’ or longer. Consider the shipping cost when using material that is longer than 84” in length.
Is strapping Required behind the T&G Boards?
Strapping the walls is a popular option to create an air gap behind the T&G boards. This is recommended for outdoor saunas, on an exterior facing wall, or anywhere that moisture could be a concern. When installing horizontal T&G, the boards will be nailed into the studs. For vertical installation, there will often be nowhere to nail the board into. Horizontal strapping is required to attach the vertical boards to the wall. However, strapping can be skipped if horizontal T&G is used, and the sauna is indoors.
What about the ceiling? Which direction should it run?
Most sauna kits will include T&G panels in the short direction. There are two reasons for this. First is a visual preference for sauna bathers. When the boards run in the long direction, it could make the room appear longer. Second is a cost preference. Cedar T&G boards are at a premium, and longer boards cost more per foot. In order to keep the cost of the kit down, boards are provided in the short direction by default. It is cheaper to run the ceiling joists in the long direction. However, if your joists run the other way, you can strap the ceiling as per the above paragraph, to run the T&G in the direction you choose.
