My house has 3/4 inch hot and cold pex trunk with 1/2 pex t'd off of it to feed the sinks, showers, etc. It is a two story with two full baths on the second floor and the main has master bath with a separate shower and tub. I have 3 daughters and my wife in the house and many of the showers and tubs seem to be turned on at the same time. Which has effected water pressure. Yes, I can tell them not to take a bath at the same time...but some things are easier than others... I am in the process of finishing the basement and was thinking about running another 3/4 line to feed the downstairs finished bath and also feeding the master walk in shower (right above the lower bath and easy to re-pipe). The hot water heater has a 3/4inch going out and so does the water softener.
Will adding another 3/4 trunk line off of the 3/4 hot and cold water outlets improve any water pressure loss from the upper baths if they are on a separate trunk?