Hi,

I came across this site while doing a quick search on "loud knocking sound coming from pipes" I have read Tom's responses and feel like I know what is occurring, but a little reassurance never hurts.

Here is the situation.

I live in a newly built home, 11 months to be exact, and recently me and the wife have noticed this loud knocking sound coming from the walls whenever hot water is run throughout the 2 story home. At first I thought it was from our water softener but that was later rejected by a home inspector who came out this past weekend. He said he has never seen anything like this in the 13 years on the job. He cleary indicated to me that it is not normal expansion/contraction that is occurring. Reading some of the responses on this board though it would appear that is the cause. The inspector noticed the knocking sound in the basement coming from the drain pipes and not the hot/cold water lines. Not sure if that is normal or not. It looks like there is a way to fix it by tearing up the drywall and tighting the pipe.

The builder does not warranty expansion/contraction so if it's determined this is the cause they will most likely tell me to live with it. How can I be certain though that it is expansion that is causing the noice? Will the noise ever stop? As stated in other posts, depending on where the water is being used, different parts of the home behind the walls will have the noise. Every time hot water is run we get that sound, I was under the impression that expansion occurs every once in a while not often, but hey, I could be wrong.

Thanks for any help in advance.

Jason

Hi Jaso9n,

It sure sounds like your pipes are expanding and contracting due to the temperature differential between the pipe and the ambient temperature in the enclosed wall space. As a rule this will go away once the weather warms up. I take it you've read my posts on this but in case you haven't I'll say it again.
Knocking, popping, creaking and crackling pipes are a common complaint, especially in colder weather. I can tell you what's happening and take the mystery out of it but you're not going to like the repair. When a draw is made on a hot water line the line expands against a pipe strap next to a stud and when you drain hot water from your tub or shower it goes into a chase that is a little cooler then room temperature. The heat expands the pipe causing it to rub against the stud to which it is pipe strapped. This is the sound you hear. As it cools it contracts and the noise is heard again. To repair it you must tear open the walls and locate the pipe strap that's causing the problem and shim it tight. Most people when they learn what causes it just elect to live with it. Regards, Tom

Understood Tom for sure and thanks for the reply. In fact I copied your reply from another post, which seems to be almost verbatim as to the one above, into notepad so I can reference it with the builder. My only main question was can this knocking, expansion, etc. occur in drain pipes? The inspector made me feel as if it was not common in a drain pipe as opposed to the hot/cold pipe.

Since the house is still under warranty, I guess the builder would have no other choice but to tear up the walls. It's just a tough concept to fathom that every year when it's cold we'll have to deal with this unless it gets fixed. Is it normal for this to occur within such a short time frame, I mean we've only been in the house for 11 months.

Thanks.

Jason

It was "verbatim" Jason. I have a data base that I copy and past from.
You ask, " My only main question was can this knocking, expansion, etc. occur in drain pipes? The inspector made me feel as if it was not common in a drain pipe as opposed to the hot/cold pipe."
Sometimes inspectors can be a little dense. What do you think happens to a drain pipe that's located in a chilly chase inside a wall when you drain a tub full of hot water? That's right, sports fans, it expands. Now what happens to the same drain pipe when it starts to cool down? BINGO! It contracts.
Noise doesn't just stop with water pipes, drainage's affected also.

" Is it normal for this to occur within such a short time frame, I mean we've only been in the house for 11 months."
Time has nothing to do with it. If conditions are right it can happen the day after you move in. Your builder/contractor's going to fight this. It means opening up the walls. But wait! Once the walls are opened up the temperature inside the chase will become the same as room temperature so how do you tell which pipe strap needs to be shimed? Correct again! You can't. So that means every pipe strap will have to be shimmed to be sure that, when you replace the dry wall and paint, it doesn't happen again. It means a lot of lot of work, a lot of dust and dirt, and a lot of hassle for both you and the contractor. Think this out very carefully before you start tearing up your walls. You're going to hafta balance the hassle as per against the aggravation before you decide. Good luck in whatever you decide. Tom