Trained Eye

 
 
 

Water Hammer & Caulking in Tub

Question:

We moved into our 4-level split house last year, and performed numerous renovations as the house was quite run down, even though it's only 14 years old. However, we noticed a couple of problems within the house that we haven't been able to resolve.

Our 4-piece bathroom on the third level has a bathtub and shower. When we turn on the hot water tap, we notice that it vibrates and make a very loud thumping sound. If we turn the hot water tap full blast, the sound is not as pronounced. Also, we have re-caulked around the bathtub as we noticed the original caulking was cracked. However, after only a couple of months it separated once again. What would be the reasons for this and how can we fix it?

I read your article all the time and any suggestions that you may have would be greatly appreciated.

Answer:

The two inquiries you have are unrelated but are both plumbing-related issues and will be answered together. First we will deal with the noise from the plumbing pipes, which may be due to one of several causes. The banging noise is due to the change in pressure within the plumbing pipes, when your faucet is opened. There may be one of a few reasons why this is happening and we will explore some of these.

The noise you are hearing is often referred to as “Water Hammer”, but this may not be the actual occurrence. Water hammer is caused by quick changes in pressure and is often solved by adding small sections of extra supply piping, with sealed ends, to even the pressure within the pipes. This repair, although inexpensive, should be the repair of last resort if other solutions do not fix the problem.

In your case the problem may be due to poorly secured pipes. They may be rattling or banging against themselves or wooden framing within the wall cavities. When the faucet is opened and the pressure changes within the pipes, they may vibrate or move, often dramatically. If they are not proper secured to the wooden framing within the walls with proper clips or brackets, or if these have come loose over time, the pipes will bang continually. This may be the most difficult to repair, if the pipes are not visible. If any pipes leading to this bathroom are exposed, they should be checked and re-secured as well as possible.

The last possibility to explore is the tub faucet itself. Older faucets will not have a pressure-balanced system and may have old seals and washers that wear out over time. When the older units wear, they may not operate as designed, and allow the water to rush out through the valves too quickly, causing a rapid change in pressure and the corresponding noise. This can be checked by very slowly opening the faucet to see if the banging occurs. If this is the case, replacement of old faucet parts or updating the faucet is the solution. This may not be conclusive evidence of the problem, but older faucet parts are often inexpensive and easy to replace and should be the first place to start.

The deterioration to the tub caulking is not unusual, but may be a bit premature. First, you should ensure that you are using 100% silicone caulking, which is specifically designed for bathrooms and includes a fungicide. If not, the caulking itself may be the problem. If this is verified to be the proper caulking, there may be a simple answer and solution for your problem. The caulking may be initially adhering to the tub and wall, but will let go when the tub is filled with water. The weight of the water in many full bathtubs, especially fibreglass acrylic units, is enough to cause the tub to flex and drop slightly. This may not be visible to the untrained eye, but will often pull the newly installed caulking away from the wall, causing the separation you noted.

The solution to this common problem may be one of the simplest of all minor home maintenance issues. First, the old caulking should be removed and the area fully cleaned before re-caulking. Then the tub should be filled with water, almost to capacity, before re-application of the silicone. The tub should be left full of water until the caulking has cured, up to 24 hours depending on the caulking. Once the water has been drained, the caulking may bulge, slightly, but will not pull away from the wall as before.

 

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