Soundproofing the floors

Audio Systems
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The background is that, while we have brick walls throughout the house, the sound insulation between the floors is pretty awful. Given that my wife’s study and the children’s bedroom is above my listening room, this has been somewhat problematic!

My intention is to try and fix this and @Ermos was asking how as he had a similar issue. As I don’t have all the answers, I thought I’d open this as a new topic for everyone to contribute to or gain some knowledge from.

My understanding so far is that we will need to have some kind of sound insulation material between the joists as well as needing to create a floating floor (likely with a layer of fibreglass, however I believe rubber can also be used, but is more likely to fail).

I think at this point, I’m going to need to get some experts in to advise, but wondered whether anyone else has done this or has any knowledge on this topic?

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We have ceramic tiles in our bathroom, over floorboards. The bathroom is above the kitchen. All bathroom sounds (flushing and, yes, those ones) were clearly audible in the kitchen and, depending on the company and the sound, this was either inconvenient, humorous or rather embarrassing.
As part of a wider refurb/extension project, we needed to soundproof a downpipe which had been outside the house but would now be inside (even worse!). So I asked one of the guys to place some of the same highly effective bitumen sound-deadening material they’d wrapped around the downpipe under the loo: he lifted the toilet, seated it on the material and refixed it through tiles to floorboards. A sonic transformation. I think the same material is used under car bonnets (US: hoods) for the same purpose. Heavy, slim, and remarkably effective. Hope this gives you some food for thought.

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My son is a gamer and on weekends would stay up late talking into his headset, bothering his sister in the next room. We bought some “soundproofing” tiles from Amazon and put those on the wall. They helped, but not entirely.

You could try something like this on the ceiling as an inexpensive experiment. However, I doubt it would do much good, especially with bass.

There’s always headphones! Many of us use those for the reasons you need. It’s a different experience and some don’t like it, but I do, and you can get really fantastic headphone gear. Like dCS!

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The floor joists may be the most difficult part to deal with! Looking forward to hear how you get along. Great thread.

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I don’t pretend to be an expert but I think you need to decide what you mean by “soundproofing”.

If you are looking for a way to reduce the noise of, say, people walking across the floor upstairs this could require a different approach to that of silencing loud music across a wide bandwidth especially where low frequency tones are concerned. I do know from experience how devastating the latter can be. I have adjacent neighbours and when I tried a subwoofer some years ago I found the transmission of low sound through my own place was significant and capable of disturbing others. I decided to forget that bottom octave.

Dealing with the long wavelengths of low frequencies is not that amenable to added insulation but requires decoupling. One of the few examples I can recall that dealt with such transmission successfully was the approach of Air studios when they were situated at Oxford Circus and had to float the entire studio from rubber girders. Yes, true soundproofing in a multi occupancy stricture can require this sort of heroic approach.

Also I think that you are in the UK (?) and the construction of typical homes is very different to, say, the USA where stud walls are used as opposed to the UK where rick or breeze block are common. So some approaches may not be applicable for all locations.

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@jandersonhill It really depends hugely how serious you are about abating the noise. Is the ceiling in your listening room made of drywall? Are you willing to pull that down. Its really messy and dependent on the size of the area can add up. Ideally you would remove the ceiling of the space above your listening room and fill the cavity between the above floor joists with something like owens corning 703 acoustic insulation and 4” thick minimum. If it already has batt insulation leave it and add the 703. The joists will be at least 6-8” deep. Maybe deeper. You would likely encounter electrical and maybe even plumbing. Also most acoustic insulation comes in 2x4 sheets so they would likely need cutting to fit the likely 16” joist spacing. To further insulate and sound proof you could add a surface skin of mass loaded vinyl which comes in 4’ wide rolls. To top this off, replace the original drywall with “quietrock” drywall which is pretty effective in reducing transmission of sound. Probably goes without saying but thicker is better. It depends how far down that rabbit hole you want to go. There is acoustic caulking for every crack. There are special seals for penetrations like outlets and lighting and sound can travel around the surface you are doing. This can be complex but if you do any of the above it will make big changes. The cheapest start would be adding a surface layer of drywall to the existing ceiling. Just adding the mass density could dampen the sound transmission significantly. Another concern is shared hvac ducting. If younopen the ceiling you may look at insulated ducting if it is shared up and down. Its an easy way for sound to travel. Good luck

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Agreed! I have a Mjölnir amp and Stax SR-X9000 headphones to help bridge the gap, but it’s definitely not the same experience.

They are damned good, though, showing up weaknesses in my previous speakers!

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I think the best panels do make a difference, but ideally you need to cover the entire cavity behind the wall to make this truly effective. The problem with the bass from speakers is, I suspect, whatever we use needs to be pretty thick and dense to block the sound.

I could go up two floors and it was like living above a disco!

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Hysterical!

:joy:

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I half-feel like I’m opening Pandora’s box. It’s going to need the whole of that floor raising, which might create problems with one or two bathrooms. I’m expecting the fibre-glass to sit on the joists, although, some kind of rubber compound would probably require less depth.

Then we have to consider the downlights which might not take well to being so well to being insulated!

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No real issues with noise from people walking across the floor, this is ‘purely’ to resolve the issue of silencing music, which is far more troublesome. I believe insulation between the joists will cut a lot of the noise, but (as you suggest) they’d still be transmission from the ceiling to the joists to the floor above.

If we go through the effort of doing this, I won’t be allowed to do it a second time!

Agreed, my understanding is we’ll need to do both to be able to reduce the whole spectrum of sounds. Either that, or the family will have to get used to living above the Berlin Philharmonic :wink:

Good point. Nowadays, many houses are built in the UK with plasterboard walls, ours is (internally) plasterboard over breeze block, which means we don’t get much noise through the walls, only between the floors.

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As above, do a search on something like “bitumen sound proofing” and you will get a mix of building and automotive products. It’s dense stuff so slim and heavy; I used the same to tame some solid wood speaker cabs and the end result sounded as good as the MDF equivalents. Works across all frequencies.

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Thanks Jeremy for taking this up!

We are in a fairly large loft of 10 x 16 metres and it is nearly 5 metres high.

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Walls and ceiling have been isolated, now we need to do the floor. Our neighbours under us are very sensitive to all kinds of noise (except their own :wink: ) so we have to take action, otherwise I can only use my headphones.

We have had 2 consultants over, and their reports are at the least contradictory. My audio dealer suggested smaller loudspeakers, of the ultra expensive kind, but no guarantees to the neighbours, of course.

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Bitumen sounds like it’s worth looking at :smiley:

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I have some experience in sound transmission through structures and in fact also in my own house. I assume you are concerned with upward transmission from a lower floor to the study and bedroom above.

There are two ways in which sound will transfer from one level to another. there is the more obvious in the form of airborne sound. That requires the upper and lower spaces to be as well sealed as possible but also requires mass in the floor/ceiling. Just filling joists with glass or rock wool will not be sufficient. One way to introduce mass is to support high density boards (such a high density and thick plasterboard between the joists, several layers is better than one, some I know (not me!) have even used sand contained in plastic bags but it is heavy and may be too extreme. There is then no harm in packing the void with something like mineral wool (which is denser than glass fibre). If possible add a second layer of plasterboard to the ceiling below and hang on resilient hangers. Then add a floating floor in the rooms above and try to make sure you don’t have downlighters penetrating the ceiling. You need to check that your existing floor joists will take the additional weight without problems, though.

The second means of transmission is structure borne sound. I assume your ground floor walls extend continuously to the upper floor and so unfortunately you have a ready made route for structure borne sound which will be hard to resolve. You could try to minimise this by adding a floating floor to the ground floor, making sure the floor is not connected to the walls, in order to reduce low frequency vibration from your speakers. Alternatively (or even additionally) use a method of isolating your loudspeakers from the floor.

I recently finished a house refurbishment in which I wanted a listening room and cinema which is located above a living room. I was concerned about sound transmission in reverse to your situation, ie from above the room below. the existing floor was badly constructed and it was possible to make it bounce by just walking across it!! Not very promising for sound transmission. I went to the extent of having the entire floor removed, additional steelwork added to stiffen the floor, adding mass between the joists, a double layer ceiling and floating floor above with water based underfloor heating. The loudspeakers are placed on Wellfloats.

This method has reduced sound transmission but not eliminated it. Another problem I had was with two Perlisten 15 inch sub bass units, these are not part of the two channel audio system, just the cinema system. On certain film soundtracks the house was being subjected to very low frequency vibrations, not unlike an earthquake and I began to fear structural damage to the house. I should hasten to add that this was at even moderate listening levels. The solution was to have my dealer recalibrated the sub bass units so the bass rolls off below 20Hz instead of 16Hz. That has made a huge difference.

So has all this worked? To an extent, yes, but I am limited by the fact I have rather large hole in the floor for a spiral staircase. However, I believe it is better than if I had done nothing, but it is not perfect and I don’t believe it ever can be in a domestic situation. So, if you are realistic in your expectations I think you can improve things but you will probably not easily find a cure for complete “soundproofing”.

By the way I am not an acoustic engineer and so others more qualified than me may have better ideas, this is just an account of what I have done.

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Prior to hacking the wooden floor, I think I’ll start with 2 sets of 4 of these under the 2 main speakers:

And then something like this:

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The GAIAs are very, very good!

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Thanks Jeremy, but will they also decouple the speakers from the floor? Enough to significantly mitigate noise travelling down through the floor? At least at moderate listening levels?

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I’ll chip in and mention that I use Isoacoustic pucks from the professional range. Same kind of thing but without the metal finish and much cheaper. I don’t know if this helps as circumstances vary but my downstairs neighbour says that she cannot hear me at all. That’s from a pair of ATC ASL 50s.

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I doubt it would hurt, but I can’t answer conclusively as my man cave is on the ground floor with nothing beneath me. I think there could still be some transmission of bass frequencies, but I would imagine it would help with the higher frequencies

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