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Robert Lamoureux: Pipes that shake, rattle and roll

Your Home Improvements

Posted: August 13, 2010 9:19 p.m.
Updated: August 14, 2010 4:55 a.m.

Hi Robert,
How can I fix rattling and noisy pipes? The pipes only make the noise when the cold water is turned on. Thanks,

Hi Dan,
You’ve got a loose pipe. The only way to fix it is to try to pinpoint where the problem is and start opening up some drywall. You’ll have to use a plumbing strap to secure the copper line to the wall. The noise is caused because the pipe is close to a 2” by 4”. When you turn the water on, the pressure through the pipe is causing a vibration and the rattle. 

While you’re at it, check the pressure. Make sure the PRV is not too high. Sometimes high pressure will cause the same problem. If the pressure is set too high a sudden surge of water will rattle the pipes. Code on PRV says 80 lbs. My rule of thumb is 70 lbs., which will give you plenty of volume and plenty of water. Set it lower to save water. Personally, to not waste water, I keep my home pressure set at 60 lbs., which is fine for dishwashers, showers, garden hoses — whatever you need. Also, the lower the setting, the less chance you have of blowing out water lines because of high pressure. 

Mr. Lamoureux,
I had a leaking showerhead and called a handyman to fix it. He replaced the cartridge, but now hot water comes out of the cold side and cold water out of the hot side. He said he was going to come back, but didn’t. How can it be repaired? Thank you,
Jeri C.

Hi Jeri,
The cartridge was put in backward. What you need to do is shut down the valve and pull the cartridge out and reset. Basically it’s just a stem, with holes on top called ports that were reversed.

Hi Robert,
I had a leak in my bedroom. It started out as a little stain but continued until the ceiling started to drip. We are retired and on a fixed income, so I was not looking forward to paying for a plumber. I’ve been reading your column for more than a year now and feel I can do this myself. I feel like a contractor. So, I turned off the water, opened up the wet drywall, and pulled out all of the wet insulation. I have two 3/4” galvanized pipes running up there. I didn’t see where it was leaking so I turned the water back on very slowly so I could find the leak. But now there is no leak. This is very strange because the ceiling was dripping, now nothing. I don’t want to repair the ceiling then have it start leaking again, but I don’t know what to replace. Any tips would be greatly appreciated,
Henry T.

Hi Henry,
It sounds like when you turned the water back on, it flushed some sediments through the pipe and sealed the leak, temporarily, from the inside. I would not trust this to hold too much longer and would not replace the ceiling until I knew the repair had been made. 

The area directly above the damage to your ceiling can be an indication of where the leak is located, but not always because water will travel.  Are the pipes level? Could it be leaking further up the line and running down? If you’re not sure, replace everything that might be leaking to be safe.   

If you replace the galvanized with copper, remember to transition with a brass nipple because if you connect copper directly to galvanized it will corrode. This is known as galvanic corrosion. One of the pipes becomes the anode, the positive side, and the other acts as the cathode, the negative side.

 When you connect two different metal pipes to each other the pipes create a positive difference and exchange ions, creating a small electric current. The water flowing inside the pipe is the electrolyte — since basically all water is slightly acidic, so what you’ve done is made a battery. 

You can also use dielectric couplings, connected to the galvanized, with the copper in between. The dielectric coupling has plastic in the middle which acts as a shield so the two dissimilar metals don’t talk to each other. You would thread one onto the galvanized side, and sweat the copper to the other side. 

Hi Robert,
I enjoy your column. I’ve got a question for you. I bought an old house to tear down and rebuild and left one of the walls standing so it would be a remodel instead of new construction. It is on a raised foundation, but since we’re in earthquake country, would it be better to pour a concrete slab? Thank you,
Gary B.

Hi Gary,
It all depends on where the epicenter of an earthquake is located. During the aftermath of the 1994 Northridge quake, one of the things that infuriated me was the contractors who drove around and claimed to be “Earthquake Experts.” There is no such thing. For example, one of our properties had one building with no damage, while the other was destroyed. Every engineer I spoke to said they didn’t understand how it all works. They said they couldn’t predict what stresses buildings will undergo during an earthquake — and these were licensed, schooled, bright guys. 

So, to answer your question about which foundation would be best, we really don’t know. 

If you do decide to level it and pour a slab, be sure to run your plumbing — your water supply side — through the walls and ceilings. 

Today’s standards call for all plumbing to run above grade — through the walls, between the floors and ceilings. Old school was to run rose tube through the slab, in the middle of the concrete, and then bring it up — which is a nightmare. 

We have designed a custom, full-color The Signal/Your Home Improvements T-shirt we will give you if we answer your question.

Robert Lamoureux has 25 years experience as a general contractor, with separate licenses in electrical and plumbing contacting. He owns IMS Construction Inc. in Valencia. His opinions are his own, and not necessarily those of The Signal. Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor, after that contractor has made a thorough visual inspection. Send your questions to


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