pipe sizing for 4 story

[P-tank]

i just moved into an old 4 story 2 family in brooklyn, ny. there's a boiler on the 3rd floor to service top 2 floors (duplex appartment), and each floor has a full bath. i think i should re-do much of the piping in the house and here are my thoughts on pipe sizes:

1" copper from street through cellar feeding 2 risers
3/4" riser for top duplex (1/2" going to boiler for hot water and then to baths)
3/4" riser for lower duplex (lower duplex has it's own HW heater)
1/2" going to each bathroom

as you might be able to ascertain by my lack of lingo i am an amateur but i have sweated lots of copper and installed baseboard heat throughout top 2 floors. also have done various plumbing fixes.

i am working on picking up a NY plumbing code book but any help on sizing would be appreciated.

[Terry]

I think you should be looking at larger pipe sizing for the incoming main line.
Here is a chart for sizing water (http://www.terrylove.com/watersize.htm)by the UPC code, not the same as New York but helpful.

Most plumbers only put two fixtures on a 1/2" line at most.
That would mean you could go 1/2" for hot in one bath, but that the cold would need a 3/4" line.

[P-tank]

ok, great, thanks for input here...