Cutting Joists For Plumbing

[mcelhane]

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

[Joseph Meehan]

I think you are looking at this the wrong way. Use cast iron pipe and it will be quiet and last almost forever.

[Speedy Jim]

You're right to be concerned about the noise.

One resource:

[e-mail]/sales/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

[PipeDown]

Yikes, at $12 per foot for 4" cast iron looks more attractive, just a little harder to install.

[calhoun]

Lets get real here. You were actually considering cutting almost 1/2 way though 6-7 joists just to avoid some sound. You will have a lot bigger problems if you do that. Not only will you lose much of the structure you also will have a horizontal run susceptible to blockage. Just dump it down the wall. Fill the cavity, around the pipe, with foam if the sound is going to bother you that much.

[Edwin Pawlowski]

It is not a good idea so don't do it.

Let's be realistic. You are building a house that costs 100's of thousands of dollars, you are converned about the plumbing noise, yet you are not willing to put in an extra hour or two of work to solve the problem? Stop being a lazy and cheap SOB and do the job right. You have to live with your decision for the next how many years?

Even the one where I called you a lazy and cheap SOB?

[EXT]

The house should be designed from the ground up to allow a chase for the drain lines. If you wanted the line to run where it will cross a bunch of joists, the joists should have been built to accommodate this run. To change it and cut the strength out of half of the joist in a room is inviting serious problems. Build it as it was designed. Have a truck mounted foam sprayer come in and encapsulate the run in foam, it will help muffle some of the sound. I am sure you will find other areas to foam up while he is there.

[Bubba]

DONT cut through all those joists. Sound insulation, installed PROPERLY, works very effectively. And remember, when cutting a joist do NOT cut the bottom or top of the joist. Cut out the center only. You loose hardly any strength when cutting out the center of the joist. If you cut out the bottom or top of the joist you almost destroy that joist entirely. Bubba

[tbasc]

I'm so glad to see this comment in print. A little forethought would have avoided the problem. TB