ticking waste vent

[Marc M]

I went to my buddies house because he thought he heard water dripping in his attic when the faucet was running. Anyhow, I went into his attic and found that when hot was on at the sink/tub etc... it would (expand/contract?) the plastic pipe and it was rubbing against the roof sheathing. I pulled the vent away from the wood and it stopped, and then let it go, just to have it continue. Any of you ever experience this?
I have experienced this with plastic water supply lines, but not a waste vent.

[Nick Ostrowski]

It happens in my house. When I'm up in my 3rd floor office and the shower is going in the bathroom downstairs, I can hear the PVC vent pipe making the ticking sound you describe due to the heat from the hot water making the vent pipe expand. I heard this in a new construction house in a powder room. Running hot water at the sink made the vent stack expand.

[H.G. Watson, Sr.]

The expansion lengthwise of the plastic pipe, esp and the expected movement with temperature changes, which is more dramatic with PVC over ABS when warmed, the restriction of same is the cause of the ticking noise. More often than not a nail penetration is the culprit which restricts and impedes that expansion/movement, hence the ticking "dripping" noise, further amplified/transmitted via wood stud, plate, etc..

Usual suspects are long trim nails from DIY trim projects, which may even be at the drainage portion (wet vent) of same, where the presence of the nail and collections of unscoured gunk on the inside and the enclosure of plumbing wall may prevent detection vis a vis a leak, or long trim nail, picture hanging hook nail, or similar used through drywall above fixture flood height (vent only portion) for DIY mounting of something. The penetration or restriction may be anywhere as the entire will need to rise/move upward to accomodate the expansion lengthwise of the warmed portion (warmed and expanding lengthwise from flow of hot drainage below or lateral).

DIY replacement of a portion of DWV using a section ever so slightly too long, especially where a change in direction, not taking into account the expansion rate can also cause, but usually it is more of a slight knock sound, as opposed to the "tick noise" similar to a slower "drip"/"drop" sound which is usually that is usually a penetration in plastic DWV restricting movement lengthwise (expansion) when warmed.

In your buddy's case it seems you have already tracked down at least a portion of the problem, in that the penetration via the roof is not entirely vertical and that the opening is not large enough or centered, and that the system's vertical movement upwards when expanding lengthwise from exposure to warming temperatures below is being restricted at the opening, bending and building until poping against deck. Changes in direction without clearance and penetrations restricting are further areas to explore, in the meantime correction to the opening and boot, correct support without impingment assuring no penetrations from fasteners or restrictions/obstructions to normal movement from expansion and contraction lengthwise and at changes in direction.

[Dom D'Agostino]

In your buddy's case it seems you have already tracked down at least a portion of the problem, in that the penetration via the roof is not entirely vertical and that the opening is not large enough or centered, and that the system's vertical movement upwards when expanding lengthwise from exposure to warming temperatures below is being restricted at the opening, bending and building until poping against deck. Changes in direction without clearance and penetrations restricting are further areas to explore, in the meantime correction to the opening and boot, correct support without impingment assuring no penetrations from fasteners or restrictions/obstructions to normal movement from expansion and contraction lengthwise and at changes in direction.


Translation:

Widen the hole.

[Billy Stephens]

Translation:

Widen the hole.
.
Oh.;)
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