How to Soundproof a Boiler Room In 5 Simple Steps (Full Guide)


Noisy boilers are a problem that is as old as the first boiler. But suffering from this horrible racket is no longer necessary. With just a few simple upgrades, you can soundproof your boiler room so that the noise doesn’t spread to its surroundings.

The areas to focus on are:

  • walls
  • doors
  • ceiling (optional
  • windows (optional)

Ideally, you would soundproof the entire boiler room, including all the walls, doors and windows, if there are any.

But usually that’s unnecessary and it would be a waste of time, money and energy. Which parts of the boiler room you should soundproof depends on the location of the boiler room.

You should definitely soundproof all the walls in the boiler room that separate it directly from other rooms.

Here’s a small visual demonstration:

The red area is the one that has to be dealt with in order to stop the noise from going into the hallway and other rooms in the house. If there is a room above the boiler room, the ceiling would also be a critical area.

So you see what I mean.  If you’re okay with the noise escaping from one side of the boiler room because it doesn’t bother you in that direction anyway, than it’s not completely necessary to soundproof that side.

How is boiler noise different from other types of noise?

Not all soundproofing materials and solutions are the same.

Some materials like soundproof foam panels are great for reducing echo and eliminating airborne noise. But they’re not very successful when it comes to blocking structure-borne noise.

The main difference is that structure-borne (also known as impact noise) is low frequency, vibration noise, while airborne noise is higher frequency, like music, barking dogs, people talking etc.

Loud impact noise is produced by boilers and technical machinery in general. It can easily pass through the wall joists as well as foam panels and other materials that are typically used to absorb airborne noise.

So for boiler room soundproofing, we need to use materials that are specifically designed to block lower frequencies.

 

How to soundproof a boiler room wall

For blocking structure-borne noise, it’s best do add adequate soundproofing material inside the wall, instead of just on the outside.

The best sort of material to use inside the wall are mineral wool batts. Mineral wool is especially effective for blocking low frequency noise, which is exactly what we need here.

When working with mineral wool, it’s important to use gloves, glasses and a mask. Otherwise it can cause irritation to the skin, eyes and sinuses. Always wear protection!

Here is an excellent video tutorial that shows you how to install mineral wool inside the walls properly:

You should cover as much of the area as possible for the best results. In addition to the batts, for insulating the smaller areas like those around electrical outlets or pipes, applying an acoustic sealant like green glue (link to Amazon) is the most convenient way to do it.

How to soundproof a boiler room ceiling

Soundproofing the ceiling is the same as any other wall, except for being a bit less convenient.

It’s the same low frequency sound that needs to be dealt with, so inserting mineral wool batts between the joists is the preferred method once more.

Again, I’d like to remind you that you don’t have to soundproof your ceiling unless the boiler room is above (unlikely) or under another room in which the noise bothers you.

With that being said, this video shows you how to do it:

Installing resilient channels (link to Amazon) as shown in the video is definitely a great addition that you can use on other walls as well. The air pocket that it creates between the drywall and the batts is guaranteed to improve impact noise absorption.

Although resilient channels are optional, you’re not reconstructing your walls every day. So you might as well aim for perfect results while you’re at it.

What if you can’t reconstruct the wall?

If you can’t place the batts inside the wall, you can install them on the outside of the wall. This can work pretty well and it has an additional benefit of reducing echo inside the boiler room.

But I don’t recommend using regular soundproof foam panels to do this job. You still need to use material that can absorb impact noise. So the panels needs to have either mineral wool, fiberglass or mass loaded vinyl in some quantity to absorb this type of noise.

There are two options you can choose from:

1. Buy professional fiberglass panels (these are the best-buy option, currently available on Amazon)

2. Make your own mineral wool panels

The first option is self explanatory. Measure how many panels you need to cover the wall. Order the panels and when they arrive easily install them on the wall using Command Strips.

Alternatively, you can use a simple adhesive. But Command Strips are superior because they don’t damage the wall and you can move the panels around. Or you can eventually remove them from the wall and use them for something else.

Having said that, home-made mineral wool panels would probably be even more effective. I’ve never made them myself, so I can’t give you any real tips in this regard. But this is the most detailed tutorial I could find:

However, make sure to use gloves, glasses and a mask when working with this material. This guy might be resistant to side effects, but that doesn’t mean you’ll be as lucky.

How to soundproof a boiler room door

To soundproof your doors from impact noise, you should use a low frequency blocker like before. But there are a few more tricks to take into consideration.

As I’ve mentioned in a previous article, hanging a fiberglass blanket (link to Amazon) from above the door is the simplest way to do it.

It doesn’t look very pretty, but you probably don’t invite guests to admire your boiler room anyway. Although you might want to after you’ve finished soundproofing the place just to brag about the results.

I’ve noticed that a few reviewers complained that the blanket has done very little (if anything) for their noise problem, while others claim that it works great.

Why isn’t everyone telling the same story?

The difference in opinion seems to be in the way the blanket was used. Some reviewers were using it mainly to block airborne noise. They also didn’t use a door sweep or any weatherstrip to seal the gaps between the door, the floor and the door frame either.

In that case, no wonder the blanket didn’t do much for their noise problem! The users that got great results with the blanket used it to block impact noise, which is the main purpose of this blanket and fiberglass material in general.

The best way to use the blanket is to hang it on the wall above the door with heavy duty hooks. This is ideal because it’s very easy to remove the blanket and hang it again when you need to.

When it’s hung, it should will cover the entire door, and also some of the area around the door frame as well.

Beef up the door with panels

Fiberglass panels or self-made mineral wool panels can serve as an alternative or an addition to the fiberglass blanket. You can install panels directly on the door using Command Strips.

By using the strips, you can easily place the panels on the door and remove them later if you want to use them for something else. This is a much better option than using an adhesive and gluing the panels directly on the door.

Seal any cracks and gaps in the door

You should definitely take care of any gaps and cracks in the door, regardless of whether you use the blankets and/or the panels.

Interior doors usually have a small gap between the door and the floor. To get rid of it, attach a standard door sweep to the door.

For the gaps between the door and the frame, apply self-adhesive weatherstrip to the door frame until there’s an airtight seal when the door is closed.

How to soundproof a boiler room window (optional)

I’ve written a comprehensive guide for window soundproofing already, with the top 5 methods covered in detail. So definitely check it out to see which of those option(s) suits you the best.

Specifically for boiler room windows, I recommend making your own window plugs. This requires a bit of handyman courage, but it’s not too difficult, and it provides the best results.

The other top option in this case is drywalling the window entirely. But if you want to keep the window, a plug will allow you to get rid of the noise when you want to and will keep the window functional as well.

To create a window plug you will need:

  1. a soundproof panel (or a self-made panel)
  2. a backing board 
  3. a handle

Here is an excerpt from the previously mentioned guide on how to make a window plug:

A window plug is only effective if it completely fills up the space within the window frame, so you need to measure everything correctly.

The window plug should occupy at least half the depth of your window seal; a 4 inch window sill, for instance, should be fitted with a plug that is no less than 2 inches thick. A little bit of air gap is necessary so the window plug doesn’t press against the pane.

To ensure that the plug covers every area along the width of the window sill, it should be designed to overlap on the window by no less than 1 inch, allowing the soundproof mat to fit securely into the window sill area.

Add a backing board made of very dense wood material to the plug. However, the chosen board should be relatively light, to aid easy removal. The backing board should exactly match the size of the window sill, meaning the mat sticks out by an inch all around.

You can choose to use an acoustic mat with an adhesive backing, or you could use contact cement to join the mat with the board.

Fitting handles (such as cupboard handles) into the window plug will make it easy to remove. Always keep in mind that these plugs will prevent light from coming in, so you want them to be easily removable.

Conclusion

Soundproofing a boiler room can be a bit challenging, because blocking impact noise is more demanding than dealing with airborne noise. The scope of the project largely depends on how many walls you need to soundproof as well.

The good thing is that all the necessary materials can be purchased online, through big retailers like Amazon who’ve for now been able to keep the prices lower than regular stores.

All in all, I hope this article has given you enough ideas on how to soundproof your boiler room, and that the result of your efforts will be a super-quiet environment.

 

Luka Baron

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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