Drain Pipe Soundproofing: 5 Noise Reduction Tips for Noisy Drain Pipes


Noisy drain pipes can be really annoying. Many bathrooms are equipped with plastic drain pipes which aren’t very thick. Anything pouring through them will be heard and the sound even gets amplified as it swooshes down the pipes. Luckily, there are a few ways you can fix noisy drain pipes in a short period of time.

Solutions for noisy drain pipes:

1. Use cast iron pipes instead of plastic pipes

Cast iron pipes are more expensive and they’re tougher to handle than plastic ones. This is why so many plumbers prefer using plastic piping.

Whether it’s PVC or ABS, plastic piping is an easier solution for them that requires less time and effort. But the end result is not as pleasant. Simply, cast iron pipes are tougher, thicker and much quieter.

If you’re willing to go through the effort of replacing the plastic pipes with cast iron ones, you’ll see a big difference immediately. Even better, if you’re currently in the process of installing piping, go with this option if you’re concerned about the noise.

2. Pick a less disruptive location for the pipes

Regardless of the type of material your pipes are made of, swooshing sounds will still be heard. It’s just that the intensity and volume of the sound will be different.

So where the pipes are routed is still important. For example, it’s better that the pipes go through a closet wall than the living room or bedroom. This is common sense but it’s often not taken into consideration.

3. Mix the drain pipe materials

There’s no need to use the same material for all the pipes. Use cast iron pipes in more critical places in terms of noise.

For example those that go beside a living room wall or a bedroom wall. And use plastic material for pipes that are less important in terms of noise.

This is a good compromise to make, both in terms of your money and the plumber’s effort.

4. Insulate noisy pipes with soundproofing material

Pipe insulation is the most popular solution on this list. If the pipes are already in place, not many of us are willing to replace anything. It’s too much time and effort that could be spent on more fun activities. Like throwing a frisbee to an overly excited beagle.

So instead of a difficult and pricey installation process, you can insulate the current pipes by coating them with thick soundproofing material.

I recommend using sound absorbing foam that is designed for insulating pipes. This foam is typically self-adhesive so it sticks easily on any smooth surface. And it provides both sound and thermal insulation.

This dense pipe insulation mat from Arrowzoom (link to Amazon), is a great choice for covering noisy pipes. It has all the necessary features: provides sound and thermal insulation, it’s self adhesive, easy to cut to size with a knife, and it can effectively prevent pipe bursts if adhered properly.

If one layer doesn’t provide the noise reduction you were hoping for, wrap it in another layer. The thicker the insulation is, the better.

If you have any leftovers after insulating the pipes, you can use it for other soundproofing projects in a vehicle or around the home. It can come in handy in any place that requires a stronger sound barrier.

A good alternative to this method is spray-on insulating foam. As the name implies, this canned foam is sprayed on the surface. It hardens and becomes really dense, thus providing excellent insulation.

This type of insulation can come in handy for hard-to-reach piping and uneven surfaces.

The key factor here is density. Some spray-on foams are not dense enough. You get a bubbly substance that doesn’t do much insulating. So the quality of the product is quite important to making this work. You should also apply it liberally across the surface. The thicker it is, the better sound protection it’ll provide.

One spray-on-foam that I’ve used in the past is Loctite’s Titefoam. I used it on wheel wells in my car. It’s pretty dense and I think it would work great for pipes. But you do have to spray a lot to make it thick. So get the larger can instead of the smaller ones that will only get the job half-done.

5. Double the drywall

If the noisy pipes are inside the wall and too hard to reach with any soundproofing material, doubling the drywall is another good solution. But it’s more expensive, especially if you hire professionals. So for pipes that can be reached, I’d stick to the foam options mentioned above.

Final Word: Soundproofing plumbing pipes

Not all pipes are equally noisy, and the location plays a huge role in how much the sound will bother you. Installing cast iron pipes instead of cheaper plastic ones, changing their route and insulating them with soundproofing material are all viable options.

Peter Bone

Soundproof expert and a staunch opponent of noise. This website is a free source of information on how to 'keep it down a notch'. I update the content regularly to keep up with advancements in the soundproofing industry.

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