Pipe expansion problem

[Zaaphod]

I am building a new house, and I'm encountering a strange problem I did not expect to have.. It's a 2 story house with a 4" PVC drain / stack vent that runs vertically from the crawlspace all the way up through both first floor, second floor and through the roof. The first floor does not drain directly into this, but the one bathroom and washing machine do drain into it. The problem I seem to have is that this pipe seems to expand and get longer when warm or hot water is running into it.. cold water does not cause the problem, but hot water draining from the washing machine or warm water from the shower both cause this pipe to expand. I don't think it's very much, but the problem I have is that the holes in the framing and in the floors / ceilings, are all very tight and as the pipe expands, it is basically trying to lift the second floor of the house off the first floor, eventually something has to give, and the pipe creaks very loudly as it reluctantly slides though the extremely tight holes. after the pipe cools off, the same thing happens again, but now it's trying to pull the second floor down, which it also can't do, to it reluctantly slides through the tight holes creaking very loudly as it contracts... I had no idea pvc would expand in its length so much that I would have to allow it free movement through the framing. I'm trying to formulate a plan to fix this issue, but I wanted to get some input about it.. what is normally done to allow for this expansion and contraction?? I made the holes tight on purpose to have a way to support the weight of the pipe. removing this pipe would be a MASSIVE undertaking, so I'm trying to figure out how to fix it while the pipe is in place. It would be difficult to enlarge the holes just a slight amount without damaging the pipe, but I thought perhaps I could cut an extremely large opening around the pipe.. but then how do I support it's weight? I also thought perhaps I could just cut the pipe itself maybe in 2 places, and somehow install a rubber coupling... then the rubber might allow one end to do the expanding and contracting. Has anyone else ever even heard of this?? any suggestions on how to fix it? I'm wondering if it's better to maybe leave one tight hole near the bottom for support and allow all the expansion to go vertical... but would this affect the seal where it penetrates the roof?

Any help or advice would be greatly appreciated!

 

[hj]

quote; I had no idea pvc would expand in its length so much that I would have to allow it free movement through the framing

Then you have NEVER worked with plastic piping. WE know that tight holes, even with copper pipes, WILL create noises if the holes are too small, or even not aligned properly. Your holes are NOT supporting the pipes, so big openings, if you can do it without damaging the pipe, is about your only solution. The pipe will still be expanding and trying to lift the second floor, but at least you will not hear it happening.

 

[Sponsor]

 

[Zaaphod]

I have worked with PVC before, but not any real long lengths, and most of it was pipe buried in the ground for sprinkler systems..
I didn't mean the holes provided support because they are so tight, but because I have a fitting and a coupler that won't fit through the hole holding up the weight of the pipe.. so if I cut that out, then really nothing will be holding up the pipe, I would like to know the proper way to hold the pipe up while still allowing movement... one concern I have is that if I allow movement at the bottom of the pipe, it will change my drain pitch.. so would it seems logical that I would want have the lower point supported somehow and allow all the expansion to be above that so I don't change the drain pitch.

 

[DonL]

What you may be able to do on the tight holes, is use a Dry Graphite lubricant.

As for lifting the floors, support at the bottom and letting the top expand makes the best sense to me.

I feel your pain. Good Luck on your project.


Welcome to Terry's Forums.

 

[Zaaphod]

Just a quick update on this for anyone else who may have had this kind of issue. I got a bit lucky with it, and solved the problem on my first try. I thought I would start by working on the easiest to fix areas first. My first choice was where the pipe went through a wall header, I decided this header was not needed in any way whatsoever because first of all, it was not load bearing, and second of all, it was between the second floor joists and not providing any help to holding the wall in place either. So I got my sawsall and cut the header on either side of the pipe, and then managed to split the wood with a chisel. Once I removed this, not only did the problem go away completely, but I also found the source of the problem. The hole in the header was actually slightly oversize, BUT there was a Wye directly under the header... What had happened is when the fitting was glued to the pipe, the excess glue got pushed up into the gap and hardened, and created kind of a rubber/plastic (not very slippery) gasket around the pipe. With this removed everything is as it should be! I just thought I would pass along the results.