Floor Soundproofing

Floor Soundproofing deep dive

All you need to know when soundproofing a floor

The information below is to help you understand how floor soundproofing works and to answer any questions you may have. The soundproofing market gen is very difficult for our customers to understand as there are multiple ways of displaying sound reduction. These could be airborne figures (Rw or D’nT,w) or they could be impact figures (Lnw and L’nT.w). Finally, you can also display a sound reduction as a ΔLw, this is a reduction figure used with impact sound reduction rather than a performance rating figure.

How do I reduce airborne sound going through my floor?

You can reduce airborne sound by adding mass to the floor. Ideally, you want to separate this from the existing structure to make the additional mass perform as highly as possible. This can be done with isolation strips, foam matting or rubber matting. The aim is to use a low-density material that won’t transfer the vibrations through to the higher-density more ridged materials.

How can I stop sound coming up through my floor?

There are several methods you can use to stop sound from coming up through your floor, including:

1. Install soundproofing matting or underlayment: One option is to install soundproofing matting or underlayment between the floorboards and the subfloor. This can help to reduce noise transmission by adding mass to the floor and absorbing sound waves.
2. Install a moisture barrier: If you’re concerned about moisture or dampness in your floor, you may want to consider installing a moisture barrier. This can be done by laying down a sheet of plastic or a moisture-proof membrane over the floor.
3. Add insulation: If you have an unfinished basement or crawlspace under your floor, you may be able to reduce noise transmission by adding insulation to the underside of the floor. This can help to absorb sound and reduce the transmission of noise through the structure of the building.
4. Install a perimeter flanking band: A perimeter flanking band is a type of soundproofing material that is used to reduce noise transmission around the edges of a room or floor. It is typically installed along the perimeter of a room, between the floor and the wall, and is designed to block or absorb sound that might otherwise travel through gaps or openings in the floor or walls.
5. Install a floating floor: A floating floor is a type of floor that is not attached to the subfloor or underlying structure. Instead, it is supported by a layer of foam or other sound-absorbing material, which helps to isolate the floor from the underlying structure and reduce noise transmission.

There are several options for reducing noise transmission through a floor, including adding mass or insulation to the floor, sealing gaps or cracks between the floorboards, and installing soundproofing materials such as matting or underlayment. You can also consider installing a moisture barrier to protect against dampness or installing a perimeter flanking band to block sound around the edges of the room. For more significant noise reduction, you may need to consider installing a floating floor or adding additional mass or isolation layers to the floor. It’s important to note that the most effective solution will depend on the specific characteristics of your floor and the level of noise reduction you need to achieve.

How can I reduce impact sound for footsteps going down through my floor?

To reduce impact sound from travelling into your structure you need to use a foam or rubber product. The ideal situation is to have a material that will deflect/compress but not bottom out. This reduces the energy of the footstep from transferring into the structure. A closed-cell foam is far better than an open-cell foam as the little air pockets trapped in the foam will not compress as easily. Rubber products will last longer in most cases but also won’t reduce as much sound as they will not compress as much. You are trying to find the balancing point between compression and lifetime, which is where the MLV and closed-cell multi-layer mats come into their own. They offer impact reduction from the closed cell foam. They also have the MLV layer on top which helps give the foam a longer life as well as adding decoupled mass for airborne sound reduction.

What is the performance of my current floor?

A Victorian ceiling will typically have a layer of lathe and plaster on the ceiling and possibly will have been over boarded with fire line plasterboard. Between the joists, they often have very little and have old, unsealed floorboards on the floor. This should perform around 35 dB.

In a newer build property, you are likely to have a single skin of standard plasterboard, minimal between the joists and an 18mm T&G chipboard on the floor which will have a better seal. This again should perform around 35dB.

The dB scale explained

The human ear perceives every 10dB as a halving of the sound. This means a 50dB reduction is twice the reduction of 40 dB. Other useful markers are:

• 1dB is the smallest difference you can hear
• 3dB is a noticeable difference
• 6dB is considered a significant difference
• 10dB is a halving of the sound

When we say a halving of the sound, most people think, ‘I will still hear half of the sound’. This isn’t quite true. If you reduce the sound below the background sound level, the sound will then be audible. I will explain more below.

How much do I need to improve my floor?

Let’s give an example. In this example, we will take the Victorian floor/ceiling build-up stated above performing at 35dB.

If you neighbour below has their tv on at 90dB this means you would hear 55dB of this sound.

Background sound level is what you usually perceive as silence and is commonly around 40 dB. (your fridge will run at around 38dB) This means if you manage to achieve 50dB on your floor you will no longer hear the TV from downstairs in this example.

So, we have a target of 50dB and we know the current performance is 35 dB. Achieving this improvement is a big stretch but not impossible! We can talk you through a range of options to suit you if you want to improve your floor.

Mass law

Mass law is one of the key aspects of soundproofing. It dictates that if you double the mass of a ‘partition’ then you reduce the sound by 5dB. This is shown with products like Tecsound and MLV. The 5kg membranes will have a performance figure of 25dB and the 10kg equivalents will perform at 30dB (Tecsound is 26 and 31dB but still has a 5dB difference)

From here, it gets significantly more complicated; many other factors come into play such as material, density, thickness, resonant frequency, de-coupling, dampening, flanking, etc.

This shows that adding mass is important, but it is far more efficient to add ‘de-coupled mass’ as this will transfer even fewer sound vibrations.

To do this you can use pimpled isolation strips for the floor joists and float a heavy floating floor on top of these for maximum sound reduction. Further to this, you have vibration-dampening membranes and MLV options available but we will tailor a solution to fit your needs depending on the floor height available and the final floor finish.

Sound absorption in a cavity

You always need to use sound absorption material within a cavity. This is the same with all soundproofing. If the cavity is left open then it can cause cavity resonance.

Cavity resonance is when the sound is stuck in a space surrounded by hard surfaces which allows the sound to bounce around and resonate like an acoustic guitar or a drum. This allows the sound to also travel freely around the space and amplify. The bigger the cavity is, the worse the baser frequencies can amplify. Think of the difference between a violin and a double bass.

Higher-density materials are typically better at absorbing the base frequencies, which is where you usually get the sound issue. Also, the thicker the absorption is, the more base frequencies will be absorbed. This is due to the wavelength of the base frequencies.

Do I need to remove the floorboards to soundproof a floor?

It is generally not necessary to remove the floorboards in order to soundproof a floor. There are a number of methods that can be used to soundproof a floor without removing the floorboards, such as:

1. Installing soundproofing matting or underlayment: One option is to install soundproofing matting or underlayment between the floorboards and the subfloor. This can help to reduce noise transmission by adding mass to the floor and absorbing sound waves.
2. Sealing the floorboards: Another option is to seal the floorboards with sound-absorbing material, such as wax, polyurethane, or shellac. This can help to reduce noise transmission by filling in any gaps or cracks between the floorboards.
3. Adding insulation: If you have an unfinished basement or crawlspace under your floor, you may be able to reduce noise transmission by adding insulation to the underside of the floor. This can help to absorb sound and reduce the transmission of noise through the structure of the building.
4. Installing a moisture barrier: If you’re concerned about moisture or dampness in your floor, you may want to consider installing a moisture barrier. This can be done by laying down a sheet of plastic or a moisture-proof membrane over the floor.

It’s important to note that these methods may not be effective at completely eliminating noise transmission through a floor. If you need to reduce noise transmission significantly, you may need to use a combination of these methods or consider more extensive measures, such as installing additional mass or isolation layers on the floor.

How to seal existing floorboards when soundproofing a floor?

There are a few steps you can follow to seal existing floorboards when soundproofing a floor:

1. Clean the floorboards: Start by removing any dirt, dust, or debris from the floorboards using a vacuum cleaner or broom.
2. Repair any damaged floorboards: If you have any damaged or loose floorboards, you’ll need to repair them before sealing the floor. You can use wood filler to fill in any gaps or cracks, and then sand the surface smoothly.
3. Install a moisture barrier: If you’re concerned about moisture or dampness in your floor, you may want to consider installing a moisture barrier. This can be done by laying down a sheet of plastic or a moisture-proof membrane over the floor.
4. Apply sealant: Once the floor is clean and dry, you can begin sealing the floorboards. There are a few different types of sealants you can use, such as polyurethane, wax, or shellac. Follow the manufacturer’s instructions for applying the sealant, and make sure to allow it to dry completely before walking on the floor.
5. Install soundproofing materials: After the sealant has dried, you can install soundproofing materials to further reduce noise transmission. Some options include soundproofing matting, soundproofing underlayment, or soundproofing paint. Follow the manufacturer’s instructions for installing these materials.

It’s important to note that sealing floorboards is just one step in the process of soundproofing a floor. Other methods, such as installing insulation or adding mass to the floor, may also be necessary to effectively reduce noise transmission.

What shall I replace my floorboards with?

If you have old floorboards commonly you will need to consider changing them for a tongue-and-grove floorboard for an airtight finish. Floorboards that are not airtight will allow sound to pass straight through. If you want to keep your old floorboards then you want to try and seal these up if possible as these will add 10kg/m2 once seal and can start working towards reducing the sound.

Chipboard vs cement fibre board?

Chipboard and cement fiberboard are both types of building materials that are used for various construction applications. Here are some key differences between the two:

• Composition: Chipboard is made from wood chips, shavings, and particles that are compressed and bonded together with a resin or glue. Cement fiberboard, on the other hand, is made from cement, sand, and cellulose fibres that are mixed together and then formed into sheets using a high-pressure process.
• Strength and durability: Cement fiberboard is generally stronger and more durable than chipboard. It is resistant to moisture, rot, and pests, and can withstand high levels of heat and cold. Chipboard, on the other hand, is not as resistant to moisture and can become soft or disintegrate when exposed to water.
• Uses: Chipboard is often used for flooring underlayment, wall sheathing, and as a base for laminate or vinyl flooring. Cement fiberboard is commonly used for flooring, wall cladding, and as a substrate for tiles or other finishes.
• Cost: Chipboard is generally less expensive than cement fiberboard.
• Weight: Chipboard is approx. 10kg/m2 at 18mm whereas cement fibre board is around 25kg/m2 at the same 18mm thickness

How do I stop my floor from squeaking?

Squeaky floors can be annoying and disruptive, but fortunately, there are a few steps you can take to stop them from squeaking. Here are a few options you can try:

1. Locate the squeaky area: The first step is to locate the area of the floor that is squeaking. This can be done by walking around the room and listening to the source of the noise. You may need to use a flashlight to help you see underneath the floor.
2. Determine the cause of the squeaking: Once you’ve located the squeaky area, you’ll need to determine the cause of the noise. Squeaky floors can be caused by loose floorboards, nails or screws that have come loose or other issues.
3. Repair the cause of the squeaking: Depending on the cause of the squeaking, you may need to repair or replace damaged floorboards, tighten loose nails or screws, or address any other underlying issues.
4. Add lubrication: If the cause of the squeaking can’t be repaired, you may be able to reduce the noise by lubricating the area. You can use a dry lubricant, such as talcum powder or graphite, to reduce friction between the floorboards.
5. Install soundproofing materials: If the squeaking persists despite your efforts to repair and lubricate the area, you may want to consider installing soundproofing materials to reduce the noise. Some options include soundproofing matting, soundproofing underlayment, or soundproofing paint.

What is the best soundproofing mineral wool for between my floor joists?

The best option for soundproofing mineral wool between joists is the 60kg/m3 mineral wool products. These absorb a good amount of the base frequencies coming through the floor. These are the mumbling sound you hear from the TV and talking which are the hardest type of sounds to reduce.

How do I fit the mineral wool between floor joist?

To fit mineral wool between floor joists, you’ll need to follow these steps:

1. Measure the width of the floor joists: The first step is to measure the width of the floor joists. You’ll need to cut the mineral wool to fit between the joists, so it’s important to get an accurate measurement.
2. Cut the mineral wool to size: Once you have your measurements, you can cut the mineral wool to size using a sharp knife or scissors. Make sure to cut the mineral wool slightly smaller than the width of the joists, so it fits snugly between them.
3. Install the mineral wool: Next, you’ll need to install the mineral wool between the floor joists. You can do this by simply sliding the mineral wool into place between the joists. If the mineral wool is difficult to fit, you may need to use a hammer to gently tap it into place.
4. Secure the mineral wool: Once the mineral wool is in place, you’ll need to secure it to the joists. You can do this using staples, nails, or adhesive. Just be sure to use enough fasteners to hold the mineral wool securely in place.

It’s important to note that installing mineral wool between floor joists is just one step in the process of soundproofing a floor.

What do I do if I have uneven joists?

If you have uneven floor joists, you’ll need to level them out before installing any soundproofing materials. Here are a few steps you can follow to do this:

1. Identify the uneven joists: The first step is to identify which joists are uneven. You can do this by visual inspection or by using a level.
2. Determine the cause of the unevenness: Once you’ve identified the uneven joists, you’ll need to determine the cause of the unevenness. This could be due to poor construction, water damage, or other issues.
3. Repair the cause of the unevenness: Depending on the cause of the unevenness, you may need to repair the joists before you can level them out. This could involve replacing damaged joists, reinforcing weak joists, or repairing any underlying issues.
4. Level the joists: Once you’ve repaired the cause of the unevenness, you can level the joists. This can be done by adding shims or wedges between the joists and the floorboards. You may also need to sand down any high spots on the joists.

Should I use an isolation strip or a furring channel on the joists?

An isolation strip will allow you to float all of your high-mass materials on top of the joists maximising the efficiency of your soundproofing layers.

If you use channels to install the mass between the joists it allows you to increase the mass without increasing the floor height but these systems don’t always stay sealed for long as the joists expand and contract through seasons causing any plasterboard or similar products to become unsealed over time.

What is a perimeter flanking band?

A perimeter flanking band is a type of soundproofing material that is used to reduce noise transmission around the edges of a room or floor. It is typically installed along the perimeter of a room, between the floor and the wall, and is designed to block or absorb sound that might otherwise travel through gaps or openings in the floor or walls.

Perimeter flanking bands are typically made of rubber, neoprene, or other sound-absorbing materials, and are used in conjunction with other soundproofing methods to create a more effective noise barrier. They are often used in multi-family dwellings, such as apartments or condos, where noise can easily travel between units.

To install a perimeter flanking band, you’ll need to remove any baseboards or trim around the perimeter of the room, and then attach the flanking band to the floor using adhesive or fasteners. Once the flanking band is in place, you can reattach the baseboards or trim to cover it up.

It’s important to note that installing a perimeter flanking band is just one step in the process of soundproofing a room or floor.

Which is the best soundproof matting?

There is a range of options when it comes to soundproof matting. The basic principle is the thicker and heavier it is the better. Different things can change this such as foam density, MLV thickness, resonance frequency, etc. The 2 and 3-layer MLV and closed-cell foam products are very popular but technologies are constantly changing and you may need a different material if you are wanting to reduce a particular type of sound. You may also need a different top layer for different final floor finishes. Contact us to find out what will work best for you.

Should you use MLV or Tecsound on the floor?

You usually want to use MLV as the top layer before fitting your carpet or laminate as this is much harder to wear than Tecsound. Tecsound is a better option commonly for directly on top of floorboards as it is a vibration-dampening membrane and will absorb vibrations from the structure.