How to Soundproof Your Boiler Room

You don’t need to have a home sound studio to want to quiet down the noise coming from your boiler room. Loud boilers are precisely as old as boilers themselves. Their loud, low, clangs are enough to disturb your favorite movie, interrupt conversations and carry over onto your gaming streams.

While loud boilers (especially boilers so loud that they wake you up!) may need servicing, functional boilers can also be major sound producers.

So, one of the first things you’ll want to do in any home with a boiler is to soundproof the boiler room. But since the sounds from your boiler will be different from the sounds in most other rooms within your home, you’ll need to use slightly different soundproofing techniques to address the problem.

How are Boiler Sounds Different?

---

If you suffer from thin walls and easy noise transfer in your home, you’re probably experiencing mainly high-frequency noise. This can be the noise from a TV or speaker system, conversations and the general movements in each room.

On the other hand, that’s not the type of noise that boilers tend to produce. Boilers produce deeper, low-frequency noises, which not only travel farther but can be transferred by (and travel through) your home’s structure. Not only are these noises louder, and likely to be heard throughout a wider area, but they’re also harder to block.

Curtains, foam acoustic blockers and other soundproofing tools that work for the other rooms in your house simply won’t touch the sound produced by your boiler. You’ll need products that are specifically designed for low-frequency noise—more on that in a moment!  

What Areas Should You Focus On?

---

Ideally, you’d soundproof all the walls in your boiler room, all of the doors and windows, and possibly even your floor and ceiling. But we don’t always live in an ideal world, and it may not be financially or structurally possible to address all those areas.

So, instead of soundproofing the entire room, you should start by focusing on the walls and door. If you have windows in your boiler room, your neighbors will probably appreciate you soundproofing those as well.

If you’re really on a budget, focus on the main wall between your boiler room and the rest of the house, along with the door.

This is because soundproofing is directional, so soundproofing the most direct routes between your boiler room and other areas of your house will make the most impact on the sound. However, that also means that sound will continue to travel through other walls, the ceiling and the floor, depending on the placement of your boiler room.

Think carefully about which wall will make the most difference in regard to sound transfer. Focus on that wall (and the door) to start. If you can afford to, go back and work on the other walls later.

How to Soundproof Your Boiler Room Walls

---

Since it’ll be emitting low-frequency structural noises, your best option for soundproofing your boiler room is internal wall soundproofing. Mineral wool batts are actually one of the best options for deadening structural noise. They’re designed to go inside the walls, so installation isn’t too difficult.

Soundproofing Steps

For maximum effectiveness, you’ll need to put up drywall over the mineral wool batts. New drywall installation is often the most difficult part of this process.

The mineral wool should be installed between the inner joists in the wall. One way that this method works is by helping to absorb and disperse the sound vibration so it can’t be passed along. The batts will be most effective if they’re installed with as few gaps as possible between them and the joists.

Important note: Mineral wool batts are somewhat irritating to work with. You’ll need to wear gloves, goggles and a breathing mask. Ideally, you should also wear long sleeves and other protective clothing. While the irritation levels commonly associated with the batts are low, you should try to avoid direct exposure as much as possible.

This method also works for soundproofing your boiler room ceiling, but relatively few houses are built in a way that makes soundproofing that ceiling necessary. The required angles will also make soundproofing the ceiling much more technically challenging.

Are Resilient Channels Necessary?

---

Resilient channels are additional pieces of equipment that will allow you to install drywall with a gap between it and the mineral wool batts and joists. These gaps, unlike gaps between the joists and the mineral wool, are hugely beneficial.

Do you need them? Probably not. Do you want them? Yeah, you should install these if you can. They’ll increase the effectiveness of your other soundproofing techniques significantly.

These work by reducing sound transfer from your drywall into the structure of your home. Since it’s the structure of your home that carries and produces the sound in other rooms and spaces, reducing initial sound transfer is one of the better interventions you might choose to make use of.

How to Soundproof Your Boiler Room Door

---

Your door is another place where a lot of sound will be transferred between your boiler room and the rest of your home. But you can’t open up your door and soundproof the interior!

Not only is the door itself a problem, so are all the gaps surrounding your door.

Here are the four essential steps for soundproofing your boiler room door:

1. Install a standard door sweep along the interior bottom of your door.
2. Use adhesive weather insulation strips along the gaps on the sides of your door (follow the directions on the package).
3. Optional: Install a fiberglass blanket, homemade mineral wool batts, or dense cork or foam on the inside of your boiler room door.
4. Maintain and replace the weatherproofing and other components as soon as they begin showing signs of wear.

We recommend dealing with the gaps first, since some doors are heavy enough to do a lot of sound-reduction on their own. Install a well-fitted door sweep on the bottom to deal with that gap without making it more difficult to open or close.

The gaps along the sides can be dealt with through the use of self-adhesive weather strips. Make sure you replace these strips when they begin to wear out, since their sound-reduction properties will degrade quickly as new gaps form. Fortunately, since your boiler room isn’t likely to see much use, the weather strips should last for a long time.

If sealing those gaps doesn’t do the job, it’s time to take a look at the door itself. A fiberglass blanket is a good option for reducing low-frequency noise without adding too much weight. The blanket can be installed with command strips or similar damage-free adhesive.

Another alternative would be creating your own mineral wool batts to install directly on the door. If you do so, remember to use protective equipment while you’re working with the mineral wool, and to seal it before installation.

Final Thoughts and Additional Tips

---

While it’s unlikely that you’ll need to soundproof the ceiling or floor of your boiler room, you can use Mass Loaded Vinyl sheets to get some additional soundproofing at a relatively low cost and level of effort.

We also recommend Green Glue for small spaces and the areas around outlets that are otherwise difficult to soundproof. While the glue won’t make a huge difference, it’s an important finishing touch for a true soundproofing job.

While all of this may seem a little daunting at first, soundproofing your boiler room is possible. Your home will be a quieter place when you’re done, and your eardrums and family will thank you!

Image 1: Amanda Slater; Image 2: Knauf Insulation; Image 3: NY State IPM Program at Cornell University