"Mortise and tenon" is the soul of architecture. The column size of tenon-mortise structure residence should be designed in the following aspects:

1, architectural requirements: architectural design requirements determine the number and general shape of columns in the structure;

2. Selection of wood: the types of wood, including horizontal and plain, correspond to different design values;

3. Building load: combination of dead load and live load (wind load and earthquake action should be considered);

etc

So you can't simply say what the size is, because it is strictly calculated. See Code for Design of Timber Structures for details.