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PostPosted: Sun Feb 28, 2021 5:07 pm 
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Location: Brighton, England
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Hi there

I hope I have filled out my profile correctly. Hoping to get some advice on a build I am yet to start but I have my design up to a reasonable level, sketchup screenshots attached.

I am a producer, though not professional. I do not play drums but do make a racket with my guitar, various synths and mics. My neighbours do not give a monkeys, the house is fully detached and they have parties all te time anyway. That said, new neighbours may be less understanding. My main concern is the bleed of noise into the room above, which is a bedroom. As such my overall attenuation target is going to be what I can achieve with the ceiling, most of the rest of my measures are to prevent flanking routes for noise to reach the room above.

My room is 4.6m (L) x 2.6m (W) x 2.7m (H)

The long walls are both brick cavity with no fill, as is the section over the garage door. The rear wall is concrete render though I am uncertain of the composition behind.

You will notice a strange void under the floor in my diagrams, this is an old inspection pit that will be filled with concrete before screeding the floor, then laying my DPM and tanking that to the DPC and laying celotex on top. On top of the Celotex will be an engineered wood floor. I wonder if there is any practical use for a void underneath a studio space before I go ahead and fill it. I can't imaging it would be anything other than trouble.

My outer stud in the old garage doorway will be built off of a new concrete footing and the screed will lap up to this. The inner stud will be built on top of the screed. I will also be building a stud wall at the back of the room, again on the layer of screed, where my plug sockets can be surface mounted to noggins.

As the room is rather narrow I do not plan to stud the long walls but instead to use a resilient system. Reducto clips offer the smallest profile, I believe these are an evolution of the Isomax design. Unfortunately, doing this will prevent me from hanging new ceiling joists without suspending them from the brick walls, which would obviously be pointless. As such I am limited to a resilient channel system for the ceiling too. I am less worried about losing height here so will probably go with genie clips in this position. Essentially, the resilient system on the walls and the internal stud on the back wall are only being installed to prevent flanking noise reaching the room above. The rear wall is a kitchen and the internal side wall is a hallway.

There is an unfortunately placed window on one side wall which I plan to replace with double glazing and then make a plug that will stay there indefinitely (keeping the window will be a plus when I eventually move out.

I plan to replace the garage door with a double 4"x2" stud wall from the floor up to a new window that will span the width of the garage door. This double glazed window will sit on the outer skin, cavity bridged with rubber and secondary (sliding) glazing placed on the inner skin. I would like to integrate my ventilation baffle in the stud wall if anyone has any guidance on that. I don't need help with basic designs just wondered about the logic of containing the assembly within the stud work.

So, my questions:

1) I have been trying to find an appropriate equation to ascertain the bleed of sound through a window of given size. I plan to put a very large window in the garage doorway and I wonder how the quality of the window, thickness of glass etc compares to just reducing the size of the opening. Light and the feel of the space are very important to me creatively so I would prefer to up my glazing spec than decrease the size of the window.

2) Should my resilient clips, reducto clips in this instance, screwed directly to the brickwork provide adequate isolation such that the transmission to the room above is primarily through the ceiling? I know this is a "how long's a piece of string" question but I wonder if my plan makes sense in principle.

3) I do not have room for a door to open out of the room into the hallway and have come up with a plan to have two doors that BOTH open into the studio space. Ie. the outer door is smaller, in a smaller frame. I did consider cutting a fire door in half and making a bifold door in the outer frame but making that airtight would obviously be a total nightmare.

4) I noticed that the guys over at genie clip offer an alternative clip installation pattern to support up to 3 layers of soundboard which feels like a good idea but this pushes me from 34 to 52 clips and to my mind that is just going to make the spring stiffer so to speak. I wonder whether this would hinder rather than help.

5) Green goo. The suppliers in the UK seem to regard green goo as snake oil. They recommend instead to use tech sound. I know it works in a very different way but it seems across the pond the techsound is seen as the snake oil and the green goo is the sh!t. Just wondered if anyone anywhere had done a direct comparison (not holding my breath on that one).

6) Is there much point trying to fill my existing brick cavity with insulation? This would be an expensive solution but one with no impact on the size of the room. There are potential issues with doing this in an older property but I wondered if rockwool or similar would have any impact in my situation.

7) The stud walls I am putting up front and back will be lined with 60kg rockwool, some have said that the cheapo fluffy stuff is actually better and that just melted my brain. Really not sure who believe any more. Any recommended products?

8) As I am using such a slim resilient channel system I can only fit 25mm insulation behind the channels. It is my understanding that at this width the only thing this insulation will do is prevent the soundboard resonating. If I was to mount my clips on 2"x2" batten I could squeeze 70mm of rockwool in there. Is this something I should consider or will the gain be negligible (the loss of space certainly isn't negligible).

I think that's it for now. Thanks in advance. If I have posted in the wrong place or the wrong way do please redirect me, I'm new here.

Bests, Jim


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PostPosted: Sun Feb 28, 2021 10:17 pm 
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Location: Hastings, East Sussex, United Kingdom
Hello & howdo' Jim?
Good to hear from another sea-sider (I'm building a garage studio along the coast in Hastings) - nice sketchup work BTW. I'm not familiar with resilient isolation systems, but I'll try to answer your questions as best I can.
Quote:
I would like to integrate my ventilation baffle in the stud wall

I think the difficulty with this would be maintaining a sufficiently large CSA (cross sectional area) inside your baffle boxes to allow reasonable airflow and prevent noise (due to turbulence). Silencers / baffle boxes tend to be pretty massive and although I don't know what you have planned, it doesn't seem to me that two of them would fit in that space. However, I think you could probably utilise that inspection pit for your silencers.
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I have been trying to find an appropriate equation to ascertain the bleed of sound through a window of given size.
Have you seen Greg's transmission loss calculator -it's easy to use and will give you a theoretical figure for T/L of walls of varying construction. https://johnlsayers.com/phpBB2/viewtopic.php?f=1&t=21770
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Should my resilient clips . . . provide adequate isolation

Sorry, I'm not in a position to say - I would encourage you measure how loud the sound level in the bedroom is in all likely conditions, so you have a T/L figure to aim at.
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I . . . have come up with a plan to have two doors

I think in your circs you might find it's more practical to build one really massive, triple sealed door. Remember, you're going to have to wheel flight cases, mixing desks etc into the room, so the more clearance you have, the better.
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3 layers of soundboard . . . feels like a good idea

All being equal - the more mass you have in your walls / ceiling, the more isolation you will achieve.
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across the pond the techsound is seen as the snake oil and the green goo is the sh!t

I'm using green glue (combined with OSB & cement fibre board) in my build based on the experience of contributors to this forum and elsewhere who have achieved good results with it in the real world. The problem with MLV is that it's a very expensive way to buy mass.
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Is there much point trying to fill my existing brick cavity with insulation?

Short answer is "I'm not sure" - Hopefully someone will chime in here. I don't see what harm it could do, but I don't have experience of working with cavity walls.
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The stud walls I am putting up front and back will be lined with 60kg rockwool, some have said that the cheapo fluffy stuff is actually better
The purpose of rock or fibre wool in this instance is to provide damping so it doesn't need to be really dense. Imagine putting an acoustic guitar, strings facing up, in front of a speaker playing loud music. The guitar will resonate sympathetically at it's fundamental frequency and related harmonics. To damp those resonances, you only need the lightest of touches or materials - you don't need need to use a bag of sand! The same goes for any physical structure.
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If I was to mount my clips on 2"x2" batten I could squeeze 70mm of rockwool in there. Is this something I should consider or will the gain be negligible (the loss of space certainly isn't negligible).
With the limited space available, this is a tricky call but again, you could probably use Greg's T/L calculator to help you decide.
I enjoyed reading about your project Jim & I'm looking forward to seeing it progress - good luck & ATB. John

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PostPosted: Mon Mar 01, 2021 5:23 am 
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excellent observations by John on a number of matters.

yes - fill in the cavities with insulation.

i'm not sure if i read your intro correctly - the inspection pits are still hollow? or filled? if they're hollow, fill them. dirt+rocks, then slab.

on the silencers - the inter-room silencers can be roughly the same size (area of flow) as the ducts, however, plan on adding room plenums on the supply and returns to be much larger to reduce the air speed. if you're planning on recording acoustic instruments you'll want the air flow as slow as possible to eliminate air movement across the mics. you can't hear it but the mics can... i'd put those up on the ceiling. make them as soffits front and back.

on the isolation. iso clips w/ hat channel then 2x or 3x 5/8" type x drywall. green glue if going with the 2x layers. fill with R11 pink insulation (it will compress but won't be as dense as semi-rigid would). on the ceiling - you can use spring type isolators. on the concrete render wall - you might frame that out instead of iso-clip/hat channel if you have the room. the air gap may be beneficial.

just note: residential construction is always problematic for achieving isolation. the structural transfers will almost always become the main source of noise when your other efforts are completed.

on the glass - at the end of the day - density/mass is what matters - so if you go with 3x drywall on your walls and ceiling, then you should match the density/mass of the window glass to mirror that. the main thing which will set it apart is damping - the glass should be laminated and the air cavities insulated all around to ensure the air gap resonances are absorbed.

i.e. your glass panes are part of each layer of M-A-M. e.g. (you will find the correct values in the TL calculator but here) if you need to match the windows to the 3x walls - you'd want something like 3x 1/4" glass + laminate on the inside and probably similar or slightly different (this staggers the resonant freq of the panes) like 3x 7/32" glass + laminate. solid frames.

however, if you just want to acquire commercial windows, then Pella, Martin, Andersen, etc are all reputable (and there are more) which make products which will "suffice". possibly $$$.

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PostPosted: Sun Mar 07, 2021 6:43 am 
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Joined: Wed Feb 24, 2021 9:21 pm
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Location: Brighton, England
Hey guys,

Thanks so much for the replies. sorry I have been slow to respond. I experienced some problems when excavating to find a footing for the new wall. The existing slab collapsed back as far as the pit, which still hasn't been filled. Building control want me to support the new wall on concrete lintels integrated with the brickwork but those things are 100kg a pop so looking into alternatives. Looks like I have a bit of drawing board action before I get back to soundproofing.

Bests, J


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PostPosted: Mon Mar 08, 2021 9:38 am 
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Location: Hastings, East Sussex, United Kingdom
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Looks like I have a bit of drawing board action before I get back to soundproofing

Yikes - that sounds daunting! Good luck & I hope you find good solutions to your problems. John.

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PostPosted: Thu Mar 11, 2021 1:50 am 
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Isover did some testing on the MAM partitions. Despite the Partition and Acoustics Rolls being a fraction of the price, they found them totally equally effective in terms of damping the A void of MAM.
The void needs to be fully filled, with fibre touch damping the leaves. I suggest some wires or other supporters poked through to prevent it sagging down over the years.
https://electricalaudio.com/studios-and-facilities deliberately incorporated an underfloor void as a VLF bass traps. Well that's what he said anyway. Worth a read.

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