wrote:
Building a new house and my upstairs bathroom is directly over the
dining room. I'm a little concerned about the noise of a flushing
toilet (and a draining pipe) invading the quiet of the dining room. I
am assumming that most of the noise of a draining pipe comes from when
the water changes from horizontal to vertical (between floors) and
splashes at the bottom. (Is this true?) The toilet is near the wall
separating the dining room and kitchen. I could bring it down this
wall, or I could divert the toilet waste parallel to this wall and
bring the water down the wall separating the panty and the dining room.
This pantry wall is ideal because the presence of a built-in china
cabinet will certainly reduce the amount of noise coming from the pipe.
However to get to this wall I have to cut through six or seven 2x
10"s on 16" center (the pipe would be running perpendicular to the
floor joists). Cutting 4" holes on 2 x 10's just doesn't sound like a
good idea.

Also, am I fooling myself? Is running the horizontal pipe in the
ceiling for an extra 8' to get to the pantry wall a good idea versus
going directly to the closest wall and dropping it there? I am
looking for suggestions.

Here are the ones that I have heard:
1. Replace waste pipe with cast iron - cast iron is quieter - don't
like that idea - really like the ease of PVC - do not like the weight
of cast iron. However, if I do put in cast iron, how much? From the
closet bend to the crawl space?
2. I have also been told that I could add steel plates to the 2x10's
and stiffen up the joists which would allow me to drill the holes with
confidence.

Are there any other good ways to insulate and negate the sound? All
comments appreciated.

Thanks.......rwm


You're right to be concerned about the noise.

One resource:

http://www.soundproofing.org%20suppo...es/prices.html

I hear that this material is *very* effective with PVC.

I, too, vote for cast iron, all the way down.

Besides the rush of water being audible with PVC, there
is a follow-on of a tortuous "drip...drip...drip"
as the pipe completely empties. In a quiet room this
can be disconcerting, to say the least.

Whichever DWV material you choose, see if the 3" size
will be permitted (there's no sound reason not to use it).
This could result in greatly reduced weakening of beams.

Also do some research on the noise generated by toilets
available today. Not just the flush, but the refill as well.

Jim