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Soundproofing A Furnace Closet
Soundproofing A Furnace Closet
Winter weather has come, and you have turned the furnace on to heat up the house. There is nothing like snuggling up in a warm bed on a winter night and dozing off. But a loud and annoying sound coming from your furnace closet is just grating in the background, keeping you up all night and disturbing your peaceful sleep! In this article, we will help you determine what kind of noise you are dealing with and walk you through some ways to soundproof your furnace closet. Let’s dive in!
Winter weather has come, and you have turned the furnace on to heat up the house. There is nothing like snuggling up in a warm bed on a winter night and dozing off. But a loud and annoying sound coming from your furnace closet is just grating in the background, keeping you up all night and disturbing your peaceful sleep! In this article, we will help you determine what kind of noise you are dealing with and walk you through some ways to soundproof your furnace closet. Let’s dive in!
Furnace Closet Noises: Impact vs Airborne Noise
There are two types of noise you are likely dealing with when it comes to your furnace closet: impact and airborne noise. In order to address your soundproofing needs in the most effective way possible, you need to understand the difference between the two.
Impact Noise in a furnace closet
This type of noise occurs when one object makes contact with another. The vibrational energy of the two objects colliding travel through the structure before being released as sound. An example of impact noise is if the furnace is physically moving or rattling when it is running. The vibrations from this movement will likely travel through the floor or wall and can be heard from another room.
Airborne Noise in a furnace or hvac closet
If you can hear a noise but there is no physical vibration or movement, then you are dealing with airborne noise. Sounds like the motor of the furnace motor running, people talking, or dogs barking are all examples of airborne noise.
Soundproofing the Furnace Room Door
The entryways in a room, such as the doors and windows, are the most important areas to address when soundproofing, as they are the weakest points where sound is most likely to escape. Since a furnace closet doesn’t have any windows, the door is the main weak point to focus on.
The method for soundproofing a door will differ depending on if you have a hollow core door or a solid core door. So, the first thing you will want to do is determine what kind of door you have.
Hollow Core Door
Hollow core doors are cheaper and much more lightweight than solid core doors. Because of how little density hollow core doors have, they are not very effective at blocking sound. Check out our article on soundproofing hollow doors for more information.
If you have a hollow core door, your only real option is to replace the door.
Replace the Door
The best way to soundproof a hollow core door is to replace the door entirely with a solid core door. If there is airborne noise coming from your furnace closet, a hollow core door is not going to do much at all to stop those sound waves from traveling to another room in your house. Just the act of replacing the hollow, lightweight door with a solid core one will increase your STC rating by 5-10 points! From there, the next step is to install one of our Sound Lock Door Seal Kits.
Solid Core Door
If you already have a solid core door, you are on the right track. A solid core door is a dense enough barrier to be effective blocking most residential sounds, but noise is still able to escape through the cracks around the perimeter of the door. That leads us to the next step, which is to seal up around that perimeter with one of our adjustable door seal kits.
Sound Lock Door Seal Kit
Our Sound Lock Door Seal Kit is the perfect product to use to block the sound coming from your furnace. This kit seals around the entire perimeter of the door and even has a drop-down seal that closes off the bottom gap when the door is closed. By addressing these gaps with a seal kit, you will see a huge improvement in your noise reduction.
How to Soundproof Furnace Closet Walls
The walls are the next area to focus on. When looking to soundproof the walls of your furnace closet, you have two options.
Adding Absorption to the Interior of the Closet
In most soundproofing scenarios, adding absorptive materials to a room will have little impact on noise reduction. But a furnace closet is an exception to this general rule. Think of a furnace closet as a box surrounding the furnace. The walls of the box are reflective, meaning any sound waves that the furnace creates are going to bounce off the adjacent walls, and some of that sound is going to escape the closet. After you sealed up the entryway with a solid core door and a Sound Lock Door Seal Kit, you’ve sealed up the box. Now adding absorptive materials can be effective!
Lining the walls of the closet with acoustical panels or will help to absorb some of these pinballing sound waves and prevent them from bouncing around the closet as much. Some noise will still inevitably escape the closet, but sound absorption is a great way to decrease the noise level inside the closet
We recommend using CelluZorbe to line the walls of your furnace closet. It is great at absorbing sound and is a very cost effective product. CelluZorbe is composed of mostly recycled materials (cellulose fibers) that are highly absorptive and safe to touch (unlike fiberglass). Go for as close to 100 percent coverage of the walls as possible, and you will further reduce the sound escaping from your furnace closet by an additional 5-7 decibels beyond what you achieved by sealing up the doorway.
Adding Density to the Walls
The other way to improve your walls is to seal them and add density to them. If there are any open gaps, they must be sealed up (likely with acoustical sealant). To add density, we recommend installing a second layer of ⅝” thick drywall on top of the existing wall using Green Glue. While this is an effective method, it depends on the closet as to whether this is a realistic option. Sometimes there is simply not enough space to work comfortably in the small closet.
Even after adding the density to the walls, the surfaces will still be reflective, so you can reduce the noise by reducing the amount of sound reverberating inside the closet with CelluZorbe.. Just line the interior walls of the closet.
How to Soundproof the Floor in a Furnace Closet
If your furnace is vibrating against the floor (or walls) of your furnace closet, the vibrational energy can transmit through the structure and be heard outside. The best fix for this structural noise is to decouple the furnace from the floor or walls.
The best way to stop impact noise coming from your furnace closet is to isolate the furnace using rubber. We recommend placing your furnace directly on some rubber isolation pads or on a rubber isolation mat. Anywhere you feel vibrations (even ducts) is transmitting structural noise and needs to be isolated with rubber.
These rubber pads or rubber mat will decouple the furnace from the ground, absorbing all of the vibrations the furnace is making, dissipating them, and preventing them from traveling on through the floor. Check out our article on soundproofing a floor for more information on the topic.
Now You're a soundproofing pro!
Now that you know how to soundproof your furnace closet, you can finally enjoy your warm snuggly home in peace! You may be wanting to soundproof a similar room next, like a soundproof laundry room. If that's the case we got you covered.
Any questions about an upcoming soundproofing project or soundproofing materials? Reach out to the soundproof experts at Second Skin for help. No matter what the project is, we have the expertise to soundproof it!