On Tue, 25 Dec 2007 08:08:00 -0800 (PST), brent
wrote:

I am renovating my bathroom.I want to move my bathtub about 6 feet out
from the wall. My intention is to just tie the new drain into the old
line where it ties into the main stack draining down into the
basement. Is there a problem with this?I also want to build a seperate
walk in shower basically where the bathtub presently is.My intention
is to tie the shower drain into the new bathtub line before it ties
into the main stack.Is there a problem with this?This is the first
time I have attempted any plumbing and any advice would be
appreciated.
Brent

There are "points" for each fixture and after adding the points the
minimum size drain is determined. Your local plumbing codes may
require a separate vent for the shower drain unless these are very
close together. I found local plumbing codes at the local library in
the reference section.