A floor drain is too important as it will drain out all the excessive water accumulating around. But in order to decide its size you must know what quantity of water will be drained. There are different specifications that come along and you can find them through the state codes. You can even prefer the local codes as there are more or less same. Firstly you have GPM requirements which are the main factor while deciding.
Followed by it is the piping system which depends upon the flow of water. The length and size of the pipe have also to be estimated before going for floor drain. A vital concern is the grate’s area whose specification should be ideal or there might be blockage also. So a valve it fitted for backwater so that you have fewer problems due to over drain. But ensue that the quality of pipes is good or you will have to replace it again and that will be costly.