Home Studio Loft Conversion

[DanDan]

Not sure I quite follow the details exactly.
However it does appear that the main sound stopping barrier is the two layers of plasterboard. Which is not much let's face it. The roof tlles/slates and expanding foam will add a only a little. The fibre may add a little if there is resonant transmission across the gap. Given the leaky nature of the slate this may not have much or any acoustic benefit.

The sonic benefits of fibre are very often mistaken.
Consider a hut of rigid fibre, one foot thick, drums in there.
How much level would you expect to hear outside the hut?

Soundproofing is difficult and expensive. If you did manage to soundproof this are enough to keep the drums contained, how would you breathe?

Sorry if I am wrecking your hopes, but I would start looking at electronic drums. I find the great for practice and working things out, playing along with recordings.


DD

[noggindoo]

Hi DanDan
Appreciate you taking the time and replying thanks.
I have an electronic kit but you can't beat playing the real thing ! So no worries in terms of making me realize its going to be very difficult to isolate drums but I gotta try.
I have, since posting this thread tried to learn some more, but I am not an academic so please bear with me!

so hear goes my revised proposals 1.1 - don't laugh too much now
Looking at the pitched rafters first
Infill between the rafters with Knauf universal mineral wool slab at 200mm thick then fix resilient bars across the rafters then fix two layers of plasterboard.
Now a couple of question arise.. would it help if I sandwiched one of these acoustic vinyl membranes (although these seem very expensive), or use green glue between the plasterboard or how about carpet felt underlay ?

After the above construction to the main roof rafters is complete I will try to build a room in a room so to speak by construction another timber stud wall say with a 50mm gap away from the first, then infill this with 100mm thick Knauf mineral slab again fix ressilliant bars and two layers of plasterboard.

Ok I have my hands over my ears ready for comments on this one

[axeman_uk]

it's a nightmare to soundproof an attic and drums to boot

you need mass and lots of it , tile and felt will keep the rain out but the level of sound a drum kit produces they might as well not be there.

60kg/m2 is not enough if your in the uk wickes do some 200kg/m2 at 30 mm thick

i would also consider accoustic barrier mat which has the same density as lead
but this is not cheap.

my studio is in the attic and i use an electronic kit with vst drum programs.
it's not the same but it does not anoy the neighbours.

[noggindoo]

Hi
Ok this is where I start to get confused Ah hum .again .. as I am trying to grasp the basics

Read an article from a music mag that gave a formula for working out albeit a basic general guide but a value of R being the Sound Reduction Index of materials at certain frequency this was given as R = 20 log(fm)-47dB.
So if you take a bass drum frequency of say 63Hz and apply the formula I get the following values

Mineral Wool Slab at 33Kg/M3 100mm thick R = -0.64
Mineral Wool Slab at 45Kg/M3 100mm thick R = 2.05
Mineral Wool Slab at 60Kg/M3 100mm thick R = 4.55
Mineral Wool Slab at 100Kg/M3 100mm thick R = 8.99

So on this basis and my general common sense makes me want to put 100Kg/m3 mineral wool in between my rafters and stud work etc.

However reading some other posts this may not be the case so other factors must come in to play which I don’t understand – perhaps relative to the stiffness, air gaps and resonance of the material itself?

Perhaps someone would be kind enough to explain in easy terms whist I am wrestling with the two BBC documents and formulating my third crazy design

[axeman_uk]

ok trying to get my head arround this as well

if at 63hz 100mm of 100kg/m3 ridged fibreglass will reduce the sound by 8.99db , and a drum kit produces about 100db thats still 91.01db making it out side the house

[DanDan]

nogg, consider a shed. Walls and roof 1 foot thick of 100KG Fibre.
You are inside, me on the outside. Do you think we could have a conversation?

Insulation is not Isolation. That's the mantra, get with it, believe it.

In a Mass Air Mass sound stopping system, the air gap has a part to play.
If resonance builds up in there, it becomes compromised.
So we hinder resonance by inserting fibre in there.
Luckily the lighter density fibre does this job better.
20-30Kg with a full fill but not compressed hard against the boundaries.
Just enough touching to damp them too, ideally.
A light full fill. Easier said than done.
Sound will take the path of least resistance. Currently that appears to be little more than two layers of plasterboard. The GG website has tests showing performance, although much of it seems focussed on making others look bad.
I wouldn't recommend putting Lino up there, even if it has lead dust in it and is very expensive.

Again, and you know it, this is a non runner. Take time to program a user kit on eDrums. You may get to like the sound and convenience better than the real thing. It's great fun playing along with Peter Gabriel's band on a live recording. You and Manu....


DD

[noggindoo]

Hi
Thanks for all the advice I am actually enjoying finding out about this and if, just maybe a couple cogs make that epic journey and grind together in my brain it's worth it.
I have ordered Rod's book so hopefully it will arrive in acouple of days.
meanwhile .... Ref Mass Air Mass I think I have misunderstood this all along... Sooo more reading to do of the basics
nog

[noggindoo]

So I'm hopeful the book will arrive tomorrow so I can start reading.
I have scanned over the BBC document - sound insulation of partitions.
... ok I was surprised when I compared the double camden wall: Group 16 no windows no doors an average of 56 is given, also average of 20,19,27 at 63Hz with Group 38 Double Cabins on same chassis etc an average of 61 is given, also 30,29,30 at 63Hz.

Is the better result from the ply wood and dense mineral wool because it is acting as a one mass wall then a air gap then the second mass wall. Where as the double camden wall has air inbetween the plasterboard in each of its walls as well as the air gap between them or are other factors affecting these results ?

[noggindoo]

OK Rod's book build it like the pros arrived so I have started to read.... and have questions regarding building up a mass layer.
I may obviously have misunderstood this .. on-wards and down we plunge... To me the book implies when building a stud wall that two layers of plasterboard on one face of the stud work give better isolation. Now I assumed that the first layers of plasterboard is screwed into the studwork then you could either screw the seond layer through the first into the stud works or glue bond it to the first.

A bit further on in a section called constrained layer damping is discussed, where it mentions if you use general adhesive to bond layers of material together the effective isolation by this thicker piece is less than the sum of the individual sheets.
So can anyone help clarify in easy terms whats happening here for the thicker and presumably greater mass to give a lower value than the single sheets total

[noggindoo]

Hi
Before the mention of electric drums I know I will not be able to achieve fantastic isolation as my proposed studio / drum room is in the loft / attic of my home, and yes I do play an electric kit but when I want to play my acoustic kit I figure I owe it to my neighbours to at least try some sound isolation measures, as currently my neighbours side are quiet.
So in trying to think this through some more I have put together some sketches of the existing structure and a sketch indicating proposals. Following a quick read of Rod’s Book and helpful replies from DanDan and others who have answered some of my posts I hope I am in general on the right track.

I have some questions that arise… apart from my ignorance of this subject and life in general as there is a big diff between reading a book and understanding, anyway
so once you all stop laughing at the sketches…

Regarding my sketch showing Proposed Details 1

Question 1) Rod’s book mentions that there is no advantage in using resilient channel with a true double wall assembly. I am assuming that my proposals may not present a ‘true double wall situation’ so in my case the use of resilient channels would be advantageous, is this correct?

Question 2) Pending the answer to Question 1, If I can find a resilient channel / iso-clip system that I can afford, and one that can support the loading. I am correct in assuming that three layers of plasterboard would be more beneficial than two for both of the plasterboard mass layers proposed?

Question 3) Again pending answers to the above - Note in my sketch the timber support walls have a plywood face to aid their structural stability. I am unsure if adding resilient bars to the face of the ply is correct as this may induce the smaller air gap to act like a spring and transmit the sound easily ? This therefore brings up further questions:-
a) Would I achieve a better result if I did not use resilient channels at all and faced the front of the main roof rafters with plywood then fixed two or three layers of plasterboard straight on top of the ply, then repeat this sequence in the proposed inner room OR b) remove the ply from the timber support wall and insert horizontal timber struts between the vertical timber to give structural strength and use resilient bars.

Nog

[noggindoo]

bump

[gouge]

Question 1) yes

Question 2) yes and using higher density fyrchek board is even better. leave a layer of plasterboard on the internal side so it has a nice finish.

Question 3) hmm, looking at your sections there to many resilient bars and multiple layers of stuff going on. it would work better if it were simpler. give some thought to this layup.

2-3 layers of board -> -> vapour barrier -> resilient channels -> existing rafter -> 2-3 layers of board fixed to back of counter batten -> exiting roof battens -> tiles.

the insulation then goes in between the existing rafters in what is your new roof cavity.

the floor could be beefed up a little also, how deep are your joists.

is the main roof existing?
also need to check i got the vapour barriers in the right spot to prevent condensation. it's been a while since i worked in the uk.

[noggindoo]

Hi gouge

Cheers for taking a look at my sketches and replying.
Yes the main roof is existing and comprises of clay roof tiles ->roof tile batten -> breathable membrane -> approx 200mm deep rafters.

In your reply you say to consider this layup. '2-3 layers of board -> -> vapour barrier -> resilient channels -> existing rafter -> 2-3 layers of board fixed to back of counter batten -> exiting roof battens -> tiles.'

When you say 2-3 layers of board fixed to back of counter battens the only way I could do this would be to cut up the plasterboard into strips and fit it inbetween the rafters - is that what you mean?

The floor joist are 225mm deep - I am considering a floating floor on tpo of the ply and also i will prob build a small drum stage to help with impact noise.

Nog

[gouge]

yep that's right, with this type of detail you must remember to caulk around the perimeter of the boards with fire mastic and seal any penetrations.

the deeper the cavity, the better your sound proofing will be.

don't remove the existing plywood bracing, just go over it with the isolated battens. then in the corner junction of your roof/floor behind the plywood stuff some extra insulation.

for your new floating floor do a search on gearslutz for the different makeups. the one that crops up a bit is a layer of insulaiton with 2-3 layers of 21mm ply on top of it laid on your existing floor.

you will get noise in the room below your drum room though. if this is a problem then i would also consider adding a few more layers of plasterboard/fyrechek to your ceiling below as well as putting insulation in the ceiling space plus adding a layer or 2 of compressed fc on your existing plywood floor.

the aim here is to increase mass and or cavity depth. the fact that you are wanting to play drums i'd use 3 layers of board typically.

2 layer of 16mm fyrcheck with the cavity filled and an overwall wall/roof/floor makeup of 300mm gives you about 65 Rw if you make sure both leafs are isolated.

going to 3 layers of 16mm fyrchek per leaf takes you up to about 69-70 Rw just. the same layup forming a 250mm overall wall thicknees puts you back down to 65Rw

you wil need to check that your floor and or rafters will take an increase in dead load. i can't see any issue with your rafters but better to be safe than sorry.

forgot to say, don't forget to check with the manufacturers of the vapor barrier as to dew point controls.

[gouge]

to get a deepr roof cavity you may also want to consider using studs with isolation brackets in lieu of battens.

so the isolation bracket supports the stud from the rafter. that may give you another 100mm of cavity. just remember that regardless of whether yo uuse studs or battens the studs or battens should not touch the floor linings. they need to sit on pads. you then run a fire mastic joint between the internal lining and the floor lining so they are isolated also. ie. where you skirting would normally be.

from memory the brackets will be every 1350mm crs in the vertical plane. you should check with the manufacturers as the brackets are designed to take a certain load.

probably need to think about any windows/doors or stairs yo umay have. they are all weak points as well.

[noggindoo]

Hi gouge
tried to sketch up a quick section through the rafters based on your suggestion is this what you mean or have I missunderstood ?
Nog

[gouge]

yep that will work however your board closest to the breathable membrane should be able to handle moisture so you either need external greade plywood or external grade fc.

also your internal layers need a vapor barrier between the resilient channel and the plasterboard.

i also would use standard plasterboard as my internal face and the other board need to be fyrchek or similar high denssity board.

an easier way to do this is this.

do the detail with the counter battens as you've drawn for the linings nearest your roof tiles.
then
just build an internal stud wall frame and forget the resilient channel. don't attach the internal stud frame to the existing rafters.

the internal stud frame would have isolating pads with isolating tie down bolts at the bottom plate. the top of the internal stud frame would have isolating clips fixing it at the head and i would provide another row of isolating clips to the stud/rafters at mid span.

gap between studs and rafters needs to be minimum of 25mm

[gouge]

maybe have a look at these details. i can't warrant or guarantee something thrown online so treat this as food for thought. you'll also need to figure out what level of isolation you need/can afford and do a full run on each leafs isolation properties.

if you've got plenty of space in your loft then just fix the external linings to the internal face of the rafters and go from there, but usually there isn't enough space once you take into account head heights, wall depths, acoustic traps etc, so.........

i would also allow at each gable wall 600+ deep (or there abouts) acoustic treatments. if again you don't have enough space then just do one wall only.

again, weak spots are stairs and windows. no point doing any of the details attached if you have untreated windows etc.

edit** just noticed there is a nogging missing at the bottom of the internal wall linings.