Need help with supply lines to bathroom

[redgreen]

First, thanks for a great site. I have been doing lots of reading these past few months and decided to tackle adding a main floor bathroom (sink, toilet and shower). I have almost completed all the D/W/V portion and will be starting the supply lines but I am a bit confused regarding sizing.

This bathroom is directly below an existing upstairs bath and was wondering if I could tee off the 1/2" lines that supply the upstairs bath or do I need to run separate lines? The existing cold line tees off a 3/4" supply and the hot tees off a 1/2" line that is 6 feet from the water heater. Let me know if there is any other information that I need to provide.

Thanks.

[Terry]

Normally I would use at most, two fixtures on 1/2" pipe.
After that you need to go to 3/4"

http://www.terrylove.com/watersize.htm

[redgreen]

Thanks Terry. I could tee off of the 3/4 " cold pipe in the basement but I only have 1/2" coming off my water heater supplying the whole house. Is there any difference in pressure if I take the hot from the pipe going to the upstairs bath or at the supply from the water heater? I wouldn't think so.