[Bill]

I know the code says to never branch off of a 1/2" line. In other words here in VA it says (I think it still says) that all fixtures shall be fed from a 1/2" line teed into no line smaller than 3/4". In other words, NO 1/2" TEES. I dont run into problems say like when I installed a shower in a 1/2 bath that had a sink and toilet and just teed into the 1/2" lines for the sink to feed the shower. Cant see where someone will come in and run the sink and take the pressure from the shower! Only had one inspector that did not allow it and had to go back to a 3/4 line. Geeze! Give me a break!

 

[Ron]

Max fixture units for 1/2" here I think is 6.5 that in mind since my first hosebib = 2.5 and each one after that is 1 fixture unit, then I can legally attach 3 more hosebibs on the one 1/2" line, sizing here depends on the fixture units, we can connect a toilet and a shower on a single 1/2" branch and be code legal.

 

[Bill]

Thats cool. here like I said they prefer to attach the fixture directly to the main line. The only time I had to be concerned with fixture unit value was when we done a 3,000 SF addition to a house. Thats right, 3,000! This thing had 19 fixture units! The total fixture units for the entire house was I think 38. This does not count hose bibs! Just toilets, sinks, washer machines, tubs, showers, laundry tubs water heaters and such

 

[threaderman]

The general rule is you cannot pull more than three 1/2" lines from a 3/4" supply,this all depending on the system being sized properly to begin with.

 

[GrumpyPlumber]

We use a completely difference sizing system for water than drainage (f.U.'s).
You can click my link and look up the three relevant charts under factor values.
First, we add up all the factor values for each fixtures, then we use a second chart for demand factors, for either residential, multi residentiall, commercial, industrial...etc. and finally a size chart for the main.
(these all become second nature before very long...so it's not often we reference the book)

A 1/2" main will hold up to a factor value of 4.

On fixtures:
3/8" line is a factor of 1 (lav feeds & toilet)
1/2" is a factor of 2 (shower valve & KS faucet)
3/4" is 6 (Roman tub fillers, Urinal flushometers)
and 1" is 12. (not many fixtures have a greater than 1" feed...closet flushometer is about it.)

We then look up the demand factor for whatever the building is, a standard residence is .5 - in other words you multiply the total added factor values by 1/2 (.5)

A standard 3 piece bath is a total factor of 7 with hot & cold included...then you multiply that by .5 and you come up with 3.5, just enough for a 1/2" line.

We use 1/2" tee's in this situation, in fact most baths are fed with 1/2" line unless they're on the way to other fixtures and the demand calls for 3/4".

 

[I'mYourTourGuide]

In Ky, you can't supply no more than 3 fixtures from a half inch water line. Also, you're supposed to run 3/4" into the first fixture supply branch.