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Sound proofing under floor between joists - need to assess options within a short time frame

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Sound proofing under floor between joists - need to assess options within a short time frame

Postby adamotyril » Tue Feb 25, 2020 11:53 pm

Hi,

I'm just asking about options for installing soundproofing measures - specifically what material to put between joists under a floor, but above a plasterboard ceiling of the room below...please note some unusual time and practical constraints that i define below.

here are the relevent facts -

1. This is NOT a complete solution, but something I have an opportunity to do within literally a small two week time window that is about to appear while the room above is unoccupied and the floor will be coming up then being relaid.

This is happening for other reasons (refurb upstairs) so please understand - I probably don't have an opportunity for a 'perfect' solution, and I do have a constraining TIME LIMIT to act.

But I CAN pay for and install a layer (at my own expense in labour and materials) within approx ten day time bracket shortly to appear

2. The FULL(er) solution (within my current constraints) will involve installing a false ceiling in the room below (my room, where i play music)...This can be done more slowly and I will have more time and longer design window in which to do this.

3. However, as the floor is coming up in the room ABOVE ME (according to a building and occupation schedule not fully within my control) .. I DO have an option to pay for and install a layer of material down between the joists, which will be open to access when the floor comes up.

ALSO - (once the floor is down again) I can pay for high density acoustic matting to installed on TOP of the chipboard floor that will then be put in , and below (final , top layer) vinyl flooring that will be installed in the room above me.

I might also take the opportunity to install neoprene strips on TOP of the joists just before the new chip board floor goes down (then the acoustic matting can go on top of that, then the final vinyl flooring that the upstairs people will put in, sadly carpet not an option as the final layer)

So we are looking at a fairly fast intervention that i have an opportunity to fit around the building schedule that is happening on the floor above me...!!


SO.....what i would really appreciate at this point, is a quick assessment of realistic options of what i could lay down between the joists. ideally within a work period of about five days (room size aprox 8m x 5m, victorian building, prob approx five hardwood joists spanning the floor).

My assumption is a layer of acoustic grade rockwool slabs, as closely fitted as possible, at the bottom of the cavity space, placed directly on the plasterboard that forms the ceiling below (please note, I can't completely fill the space as some ventilation of joists is considered necessary to avoid things like dry rot etc).

However, there could be some other option i haven't thought about
Polystyrene balls (by the zillion) could be one idea...these are attractive because you can just pour them in... .but i think these are not suitable for sound proofing and are used as a quick *heat* insulation fix. They are lightweight, not dense, which appears to be a feature of all or most acoustic soundproofing material.

Sand (!) could conceivably be poured into the space...denser, but very heavy ! the ceiling below would not have been designed to take that weight! quicker in labour (just pour)...but could be hazardous, weighty and ill advised.

Final point - yes, someone might suggest i do the job more slowly FROM BELOW , by removing my own ceiling,...but i'm inclined to lay something now from above BECAUSE
1. now presents as a time window to do something

2.it's probably more easy to fit it downward from above than somehow reach in to spaces as i fit panels from below.

3 and finally, I actually have A LOT of headroom above me (when i'm in the room below), so there's plenty of physical space there that i can install a complete false ceiling in later. More layers and spaced materials can be put in like that in future. However, my opportunity to work on the space from above (with me working IN that room) and layering down into the space between the joists is limited.

Thanks if you can help.

Dense, acoustic grade rockwool layer is what i'm expecting as a recommendation, but if you have any other ideas, especially if it's light on labour (pouring something in)
or some other thing that i haven't thought of...then that could be of interest

with regards A
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby Sam Spoons » Wed Feb 26, 2020 12:22 am

Much less sophisticated but when I first built my 'studio' I filled the voids between the joists above with fibreglass insulation (I knew no better at the time) then used a double layer of plasterboard as the ceiling. It's effect as sound insulation is fairly minimal (though I couldn't do a before and after comparison). I suspect just filling the voids will make little difference and your additional ceiling idea may be the most cost effective. If you were trying to reduce transmission from the floor above into the music room the isolating the floor and adding mass would most likely yield better results.

But I'm no expert and rely on their being nobody moving around in the room above if I'm recording anything acoustic/critical.
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby adamotyril » Wed Feb 26, 2020 1:07 am

Yes,

my main investment and expectation of good result will be based on a false ceiling.
incorporating a complete air gap

However, I think an intervention on the floor above (while i can) will make a certain percentage of difference.

I'm basically going with this video i've seen -
https://www.youtube.com/watch?v=mN6sOSN-KVA

Here, filling the void is cited as reducing resonance within that space, which does sound like common sense. Essentially, each cavity is a teeny bit like a guitar body.... a top and a bottom layer...but also a contained area of air that obviously carries sound waves

re: what you are calling 'isolation', i'm regarding neoprene strips as a quick way to introduce a bit of that, between joist and chipboard floor. Also, that is a quick and easy thing i can do without much labour or material cost...just long strips along the top of the joists.

regarding floor layers above the chipboard floor, I prob won't be using this specific brand of mat

but re: this *kind of* acoustic mat, i have absolute definite personal recommendation from a friend that has fitted this stuff in his flat that really makes a difference to cutting down foot impact sound that goes beyond his flat to other places

pricey per meter. But dense , and also with a bit of compressability in response to impact
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby Sam Spoons » Wed Feb 26, 2020 1:22 am

Yes if you are trying to cut down noise from above then mass and isolation is going to help. I'm not sure if it will make much difference to noise transmission from below.

TBH I'd advise consulting an acoustic specialist* as I suspect you re about to spend a substantial amount of money and this stuff is not easy.

* Somebody with studio design not just domestic experience.
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby James Perrett » Wed Feb 26, 2020 2:20 am

Like Sam, I'd also suggest contacting an acoustic specialist but, in my opinion, having done a similar sort of thing in my last studio, I don't think the sort of thing that you are proposing is going to be particularly cost effective if you have the option of a false ceiling below. The main reason for treating the floor above would be in cases where the noise from footfall is a problem which isn't the case here.

Save your money (and time) for the more effective false ceiling treatment (though I'm happy for Max to come along and say I'm talking rubbish).
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby adamotyril » Wed Feb 26, 2020 12:28 pm

Thanks for all your contributions guys.

I'm very happy to hear this, because events and schedules are beginning to take over,
and it looks like the only intervention i'm going to be able to do FROM ABOVE is the 15mm acoustic mat, that will go under the vinyl floor

I'm still optimistic and happy, as i have 18inches of spare ceiling height to play with underneath (and i could STILL add something like an acoustic booth even under that

Thanks for the responses !

A
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby ManFromGlass » Wed Feb 26, 2020 2:16 pm

A friend was building a personal studio in a place with wood everywhere and no insulation. He brought in an expert who had built many top notch studios who said my friend would be wasting his money. My friend installed 24" of roxul in the ceiling and I believe really dense expensive rubber somewhere. But he could only work from his ceiling downwards.
I’m in the same building and the hardest thing to dampen is high heel shoes. I only have 12" of roxul and it helps but not enough. His ceiling insulation was very successful. You can’t hear people stomping around in the cafe above him, which is constant.
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby James Perrett » Wed Feb 26, 2020 3:04 pm

ManFromGlass wrote:I’m in the same building and the hardest thing to dampen is high heel shoes.

Yes, that's why you're not allowed to use laminate flooring in many flats in the UK as it is difficult to stop the impact noise being transmitted into the flat below. As you've discovered, mineral wool and fibreglass don't do much to stop sound transmission - mass is the best way to do that.
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby adamotyril » Wed Feb 26, 2020 5:49 pm

Hi - all this is very interesting.

Footfall and a kitchen floor, on some kind of kitchen floor surface, is what I WILL have to put up with...but i'll have acoustic mat up there, which will do a bit.

However, my scope for sorting below if very good in terms of the high ceiling space that i have that can come downwards....18 inches that can be filled in some way or other (though that space will have to accomodate ventilation fans

I don't see why i cant have some big density...then an air gap... then another false ceiling.

But then, even below that, i could still build room-within-room type structure

I'm not ever expecting total perfection that would go with a professional studio

I want to contain my own sound so i can play acoustically at any time, and reduce intrusive sound as much as is credibly possible give that it's a kitchen up there

I can decree 'no shoes most or all of the time', as i will be the ultimate master of the space above, though i won't be there most of the time
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby James Perrett » Wed Feb 26, 2020 10:28 pm

Build a decent room within a room down below and you shouldn't have any issues with noise from upstairs. In my case we had 12ft ceilings so there was a 4ft gap between the top of the studio structure and the original ceiling (which ended up as a place to store gear). 18" should be plenty wide enough for sound attenuation and ventilation but it is probably best to run the ducting before you put up the plasterboard so that you aren't crawling around in a small space.
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby ManFromGlass » Thu Feb 27, 2020 3:11 pm

I used to be beside a flamenco dance studio. They had a sprung wood floor that must have been attached to the original timber vertical supports. Even a small class sent vibrations through multiple floors and walls. I was amazed at the power of a few people stamping in mostly unison.
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Re: Sound proofing under floor between joists - need to assess options within a short time frame

Postby Studio Support Gnome » Fri Feb 28, 2020 12:42 am

Insulation between joists helps by eliminating resonance between floor and ceiling layers.

it's useful.... but of no use at all against impact noise

Mounting a new ceiling below on resilient channel in addition to your top layer approach is the most likely method to produce useful results , which will be improved upon by means of the aforementioned insulation.

60kg/m3 rock wool is easiest to fit, as it can be accurately cut to fit the void width, and supported/restrained by simply whacking a few 100mm screws in , 3-4 above to keep a void between top of insulation and the base of the floor layer, and 4 below to support , also clear of the bottom of the joists, this ensures ventilation top and bottom of the joists. and offers most effective absorption position.

Resilient channel mounted across the joists, and then double layer of acoustic plasterboard (12.5m layer then 15mm layer , mounted on resilient channel with Green Glue damping compound between the layers of plasterboard.

Keep the ceiling edges "just" clear of the walls, you can either use an EPDM/neoprene edge tape, such as Knauf resilient isolation tape.... around the edge of the ceiling, or more prosaically, some Everbuild AC50 sealant.... The tape method requires it be in place before the ceiling goes up, the sealant needs to be applied to each layer as it goes up.

this keeps any flanking noise travelling down the walls , from making it's way in to the ceiling layer . and helps it be airtight.

Mass loaded vinyl can also be used in such assemblies, but green glue is much quicker to apply, and easier , and if paying work force, it's cheaper per square meter due to the saving in application time, the material cost is similar per Sq Metre

I could say a lot more.... but.... I get paid for doing ghat sort of shit....
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