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Soundproofing Floors

How to Soundproof a Floor

How to Soundproof a Floor

As much as we all appreciate the soothing sounds of a washing machine rumbling on the floor and footsteps so loud they have to be on purpose, soundproofing the floor is the best way to remove these unwanted noises from your life. Loud noises — whether airborne or from impact — can be tough to ignore in your home or workplace, causing stress, lack of sleep, inefficient work or… all of the above. If those footsteps or rumblings from the floor above are driving you crazy, the foundation of the room is the place to start. And by foundation… we’re still talking about the floor. So let’s start with a little background and run through the basics of floor soundproofing. Then we can dive into the specifics of how to soundproof a floor.

As much as we all appreciate the soothing sounds of a washing machine rumbling on the floor and footsteps so loud they have to be on purpose, soundproofing the floor is the best way to remove these unwanted noises from your life. Loud noises — whether airborne or from impact — can be tough to ignore in your home or workplace, causing stress, lack of sleep, inefficient work or… all of the above. If those footsteps or rumblings from the floor above are driving you crazy, the foundation of the room is the place to start. And by foundation… we’re still talking about the floor. So let’s start with a little background and run through the basics of floor soundproofing. Then we can dive into the specifics of how to soundproof a floor.

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Popular Products for Floor Soundproofing


UnderBlock™ Rubber Floor Underlayment

Overview of Floor Soundproofing

When you want to get rid of noise, understanding the basics of soundproofing is a good place to start. We can’t tell you how many times someone has wanted to use (or already used!) acoustic foam or acoustic panels on a ceiling to stop noise from the floor above. It will not work! Complete waste of time and money. Unfortunately, it’s a big misconception and results in a lot of cheap foam purchases. We need to block sound, not absorb it. While sound absorbing panels will improve the sound quality INSIDE of a space by reducing reverb and echo, they do NOTHING to prevent sounds from traveling BETWEEN two spaces.

Soundproofing materials, on the other hand, are designed to block and isolate sound to prevent it from traveling from one room to another. There are three keys to effective soundproofing: (1) density (2) limpness, and (3) airtight construction. To solve for all 3, you need the right materials and the know-how to install them effectively. Fortunately for you, you found this article to get you started on the noise solution path. Or you can stop reading now and give us a call. We’re here to talk through any project to get you set up for success.

3 keys to soundproofing floors
3 keys to soundproofing floors

There are two types of noise to consider when soundproofing. Airborne noises are exactly what they sound like, sound traveling through the air. Examples include your voice as you talk, car horns, ambulance sirens, music from your stereo, any sounds from your TV, dogs barking, cats yowling, your mother-in-law calling… you get it. You are constantly bombarded with airborne noises. The key to stopping airborne noises is to block the sound energy with high STC rating materials installed as airtight as possible.

A Sound Transmission Class - or STC rating - is a number value assigned to how much airborne sound a material or partition is able to stop. The rating system isn’t perfect, but it’s a good basis for comparison between materials. When evaluating STC ratings, a rule of thumb is +3 STC points is barely noticeable, +5 STC points will be obvious, and +10 STC will be half as loud. Remember!! Eliminating sound leaks (gaps) is extremely important too. And the higher the STC rating of your floor, the more devastating a gap leaking sound will be.

Now onto the main focus for most floor soundproofing projects: Impact noises. Unlike airborne sounds, impact sounds are caused by physical collisions, like slamming doors, loud footsteps, machinery, jumping, moving furniture, etc, that result in vibrations traveling through a structure. Eventually, the vibrational energy exits the structure and is heard by your ears as noise. Another quick rule of thumb: if two objects make physical contact, you have impact noise.

Isolating and prevent impact energy from entering a building’s structure is the key to soundproofing a floor. Once in the structure, vibrations can travel a great distance, transferring sound energy to the floor below. We measure a floor-ceiling structure’s effectiveness at stopping this energy with another metric, Impact Isolation Class (IIC). A structure’s IIC rating is the lab-tested effectiveness of how it isolates impact sounds and prevents transmission of vibrations. Similar to STC, the higher the rating, the better. And the good news is, many of your options for improving the IIC rating will improve the STC rating at the same time – solving two problems at once.

soundproofing floors for airborne and impact noise

Whether you have concrete slab or wood joist construction, there are two consistent principles that should be applied to see significant results. The first principle is to always construct a proper two-sided barrier with airspace in between. Open-joist construction is the bane of floor soundproofing. Having that two-sided barrier with airspace creates a “double wall” that substantially improves noise blocking performance. That airspace should be filled with sound absorbing batt material (+5 IIC, +3 STC) and closed in with 5/8” drywall hung from our RSIC clips (+8 IIC, +10 STC). The second principle is to use a rubber flooring underlayment. UnderBlock rubber underlayment is incredible bang for your buck and can be used with most any flooring finishes or assemblies (20 or more iIC, 10 or more STC). When using UnderBlock, the floor-ceiling assembly will have an FIIC and STC over 50. Basically guaranteed good soundproofing assuming you don’t horribly botch the install. For questions on your specific situation, just give us a call and we’ll evaluate your plans.

Modifications to Basic Construction IIC Improvement STC Improvement
WOOD JOIST
SECOND SKIN RSIC CLIPS SUSPENDING 5/8" DRYWALL
+8
+10
FLOATED FLOOR
+8
+10
ADD SOUND ABSORBING MATERIAL IN AIRSPACE
+7
+3
SECOND SKIN UNDERBLOCK RUBBER UNDERLAYMENT
+20
+10
CONCRETE SLAB
SECOND SKIN RSIC CLIPS SUSPENDING 5/8" DRYWALL
+8
+10
FLOATED FLOOR
+15
+10
ADD SOUND ABSORBING MATERIAL IN AIRSPACE
+5
+3
SECOND SKIN UNDERBLOCK RUBBER UNDERLAYMENT
+20
+10

Keys to a Soundproof Floor

Wherever you have multiple story buildings, you have the potential for noise issues between the floors. Let’s avoid all those awkward “keep it down” conversations between tenants and lock that slumber party dance-off upstairs in the bonus room. You won’t even know what to do with all of that uninterrupted relaxation.

After years of solving sound issues, most floor soundproofing issues break down into two big categories. For your convenience, we’ve waited until the bottom of the article to summarize them (that’s now!). Teaching you the basics was important! That’s why this next part will make so much sense.

Furniture, equiptment, or machinery is impacting the floor

In your home, it could be an exercise bike, a drum set, or a washer/dryer. In a building, it could be stages, risers, pumps, or motors. The result is the same. Energy is traveling through the object’s structure and into the floor. The result is creaks, groans, rumbles, and rattles as the two objects contact each other.

The solution is simple: decouple the two objects, which is a fancy way of saying making sure they can’t smack into each other anymore. In some home applications, a good carpet is all you need. Any carpet will help, but a thicker carpet is going to do more to prevent that impact noise from transferring downwards. Another option is OverKill Pro closed cell foam, which we frequently use behind plastic panels in vehicles or to cushion vibrating pipes. It’s a great option for targeted applications under equipment or an appliance that's vibrating. If you need even more durability for bigger equipment, a 100% rubber vibration isolation pad will fix your issues. Put them under exercise equipment, appliances, a stage, or even heavy machinery to decouple vibrating structures from the floor.

All 3 of these solutions are great, because they’re super easy to DIY. No expertise and minimal effort required. Just be sure the two hard surfaces from contacting each other, and problem solved.

Underblock FIIC Rating

Footsteps or airborne noise is traveling through the floor

If the pitter patter of little feet or the clonk clunk of big ones is the concern, you’ve got a bit more work to do. It’s always easiest to plan ahead and do things right the first time, but sometimes the game must be played with the cards you’re dealt. And right now footsteps from upstairs are ruining your poker face.

The first step is to double and triple check where the noise is coming from. Is it through the floor/ceiling? Or is it coming through a vent? Maybe down the stairs? A good first step in any project is to be certain the root of the problem is fixed.

To soundproof a floor is actually super simple. UnderBlock rubber floor underlayment will fix both the impact noise (footsteps) and the airborne noise (the TV, people’s voices). Those two birds are lined up just waiting for your stone. If the new floor isn’t down yet, congratulations! You’ve pre-solved your problem. If, like many of us, the noise becomes an issue after the floor install is completed, it’s time to decide whether the problem needs to be fixed.

Most people choose to pull up the current floor, install UnderBlock, and then reinstall flooring back on top. If you don’t want to rip up the current floor, you can install UnderBlock directly on top of the current floor and then lay new floor on top of that. Up to you.

In 90%+ of situations, the 3/8” thick UnderBlock is going to be plenty of soundproofing. Some people want or need the ½” thick UnderBlock, but that’s overkill in most situations. To start the install, roll UnderBlock out on the subfloor (adhesive not required). The factory seams should butt right up next to each other. Run UnderBlock right up to the wall, making any needed cuts with a utility knife. Fill any gaps with acoustic caulk. Once UnderBlock is 100% covering the floor, install the flooring. For questions about your specific floor, feel free to give us a call but here’s a quick summary.

Type of Floor UnderBlock Installation Recommendations
FLOATING FLOOR
Floating floors do not require additional adhesive. They just lay on top of UnderBlock.
GLUE DOWN FLOOR
Use manufacturer's recommended adhesive for rubber surfaces.
NAIL DOWN FLOOR
Glue subfloor to the top of UnderBlock. Nails should not penetrate all the way through to the UnderBlock or a flanking path will be created.

To hit on one last thing before we wrap up… let’s assume you don’t have access to the floor above you (happens often in apartments or condos). UnderBlock won’t be an option, so take a look at some of the ceiling soundproofing options at your disposal. Between Green Glue and RSIC clips, we can still handle the problem from the ceiling side below if needed.

UnderBlock Rubber Underlayment for Better IIC and STC

UnderBlock rubber underlayment stops impact noise and airborne noise through floor-ceiling assemblies. Install it under just about any type of flooring for best-in-class noise reduction. This superhero is ready to save you from footfall noise with the best IIC and STC ratings you can achieve between floors.

  • Choose between 3/8" thick and 1/2" 100% rubber underlayment
  • Useable with floating floors, nail down floors, and glue down floors
  • Guaranteed 50+ IIC with a consultation from a Second Skin expert

Soundproofing Floors: Final Thoughts

No matter the approach you take, soundproofing your space can improve your sleep, focus and overall quality of life. It’s hard to put a value on peace and quiet, and it’s not always available to everyone. But the good news is that with a little floor soundproofing: at least one annoyance can be removed.  

Addressing a noise issue starts with research and detective work. Figure out how sound is getting into the space. Always determine the sources and paths of sound causing the unwanted noise before starting any project. Sound leaks can come through a variety of sources, so a room soundproofing project will also need to address soundproofing a wall and soundproofing a door in addition to the floor/ceiling.

When starting new construction impact noise needs to be considered. A soundproof floor and resiliently suspended ceiling gives you the opportunity to create a very effective noise barrier. If you’ve got questions, give us a call and we’ll be happy to talk you through your project. We know that if the job is done right, you’ll be floored.

Have questions about your project?

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