Soundproofing Control Room in Ireland, advise needed please

Hi Everyone, My name is hally and I am located near Dublin in Ireland… I am at the planning stage of my studio build and need help making a few decisions on how I propose to isolate the control room from the rest of the dwelling. The control room will be used for mixing / tracking music; it will also act as a video editing suite and for recording acoustic instruments and vocals. I also wish to construct a machine room adjacent to the control room. On completion of the control room I will be starting construction of the rest of the studio, 2 live rooms, toilet, and green room. The Control also needs to be sufficiently soundproofed to eliminate as much sound coming from the live rooms. I previously posted my plans for the whole studio which includes other areas of the building (live rooms, etc) but I became so overwhelmed by the entire project I have decided to work on a room by room basis. This suits my head and my budget. It also means that when this control room is complete I can move in to begin work while continuing to build the rest of the studio. My main goal for the Control Room which is an attic space ( an inverted V shape) is to limit outside noise (dogs, heavy vehicles, etc) from entering the room and isolate the noise within the room from the rest of the dwelling. The sound levels within the CR will be generally at normal mixing/ recording levels. The work to date carried out on this attic room has been to create an entrance into the room through what used to be a 12” Cavity gable end block wall and the installation of a timber stairs leading up to this entrance. As you will see in the pictures below the room is bear, a blank canvas you might say. Room Dimensions: W 12’ X L 24’ X H 7’8” @ the apex of the roof. Floor Square footage: 288sq feet The Roof: Tiles sitting on 2 X 1 battens on felt on rafters on 8” x 3” purlins… The Block Walls: 12” Cavity Concrete walls, consisting of (from the exterior inwards) Plaster Skim, 4” block, then cavity, then aerobord, then 4” block. (Cross section pic. below) Rafters: 5” X 1 ½” @ 16” centers, 18 rafters running each side of the apex. Floor Joists: 7” X 2” @ 16” centers. These joists are supported (sitting on ) the exterior walls and they span to about half way across the width of the building where they are nailed together and sit on an internal 4” block wall below. Partition Wall: 3” X 1 ½” Stud partition acting as perlin to support the rafters. I have been advised by an engineer that it is possible to move this wall back 4’ by inserting a Reinforced Steel Joist to extend the width of the room to 16’ if this alteration would be acoustically benificial to the room... Here are a few floor plans, pictures and 3D shots of the room Aerial Views of the attic space and machine room Cross Section Drawing of the Back of the Building Floor Plan Drawing Photographs of the Room as it is now Cross Section of External Block Walls If anyone requires more details about the structure of the building don’t hesitate to ask, I have drawing plans of concrete slab foundation, etc. Testing with Sound level Meter I hooked up a pair of speakers in the room below the attic space and played a drum loop and a deep bass pattern through them. The sound level meter was set to slow dBC reading and the level next to the speakers was max 103.3 dBC. Upstairs the meter read 87dBC and the floor joists were buzzing (it was a very deep bass sound) The reading in the attic normally without music blasting from below with normal everyday passing traffic, water tank, birds, etc was from 47 – 55 dBC. My Plan for Soundproofing 1.To treat the Floor of the attic/ Control Room I am considering following Rods guidelines from his book. My joists as they are do not have any cross bridging… 2.For the existing partition wall made from 3” X 1 ½” Studs (this wall cannot be moved as it is load bearing) I thought I would again follow Rods guidelines by adding another 3” X 1 ½” Stud partition behind it with air space between them, both these walls will be sitting directly onto the joists. 3.The existing cavity block walls, it has been suggested to me that the STC of these walls would be pretty good as they are, so I thought I would just add one layer of plasterboard for aesthetic reasons. Ideally I would like to insulate these block walls with some fiberglass behind the plasterboard but this would mean erecting some studs on the walls and I think I would be then creating an extra leaf to the wall. 4.The roof, this is really tricky and to be honest I am lost as to the best way to approach it. The building regulations here in Ireland state you must leave a 50mm gap between the roofing felt and whatever insulation you put in the roof. This is to allow the roof to breed and something to do with condensation (i think). Head room is at a premium in this room so I am unsure what my options are. But to start the ball rolling here’s what I’m thinking. Roof Tiles, felt, air gap, 2 layers of 9mm or 11mm plasterboard, standard fiberglass, resilient channels, 2 layers 9mm or 11mm plasterboard. All sealed appropriately. Below is a cross sections drawing of the proposed roof treatment…. My Questions; THE FLOOR 1.Is the treatment for the floor of this room the best option or should I be considering other methods? 2.Assuming my suggestion for the floor is the best way to go is it safe to assume that the 7” X 2” floor joists @ 16” centers will have no problem in carrying the extra load? 3.Currently there is no bridging between the floor joists, should this be still be installed after the plasterboard has been put between the joists? THE PARTITION WALL 1.Is my approach here the best option? 2.Behind the existing single layer of plasterboard there is a thin sheet of plastic, does this need to come out and should I just remove the single layer of plasterboard and start with the new installation? THE EXISTING CAVITY BLOCK WALLS 1.Again, are my proposals for these walls ok, any suggestions welcome? THE ROOF 1.I am really just guessing as to how to treat this section of the room and because it covers such a large surface area of the room its imperative that I get it right, please advise as to my best options here? GENERAL 1.Should I be thinking about altering the internal shape of the room, ie. Slanted walls, etc. Thank you for taking the time to read my post and I look forward to your responses and advise. Warm regards hally

Great post with its detail! The other one you did without the drawings was too cryptic. The drawings cleared up things very much.

My Questions; THE FLOOR 1.Is the treatment for the floor of this room the best option or should I be considering other methods?

It is one of the weak links along the ceiling. What can you do with the bottom of the floor. That is the ceiling of the room below?

2.Assuming my suggestion for the floor is the best way to go is it safe to assume that the 7” X 2” floor joists @ 16” centers will have no problem in carrying the extra load?

No idea, check with a structural engineer.

3.Currently there is no bridging between the floor joists, should this be still be installed after the plasterboard has been put between the joists?

I would definitely put in bridging to increase the rigidity.

THE PARTITION WALL 1.Is my approach here the best option?

It is a good one. I would increase the number of layers and use Green Glue between the layers. I would also check if the floor can support the weight.

2.Behind the existing single layer of plasterboard there is a thin sheet of plastic, does this need to come out and should I just remove the single layer of plasterboard and start with the new installation?

THE EXISTING CAVITY BLOCK WALLS 1.Again, are my proposals for these walls ok, any suggestions welcome?

It is fine.

THE ROOF 1.I am really just guessing as to how to treat this section of the room and because it covers such a large surface area of the room its imperative that I get it right, please advise as to my best options here?

I have no clear suggestions at the moment. It is the other weak point

GENERAL 1.Should I be thinking about altering the internal shape of the room, ie. Slanted walls, etc.

The only problem is the 1:2 ratio of the length and width. the length will have to be reduced to correct this. Andre

Thanks Andre, Thanks a million for ur input, i will try and answer your questions below quoteing your inquiery... My Questions;

THE FLOOR 1.Is the treatment for the floor of this room the best option or should I be considering other methods? It is one of the weak links along the ceiling. What can you do with the bottom of the floor. That is the ceiling of the room below?

The ceiling of the floor below will be 2 layers of plasterboard on resilient channels and if budget allows green glue in between layers. Fiberglass will be between the floor joists along with my proposed installation in the images below

The only problem is the 1:2 ratio of the length and width. the length will have to be reduced to correct this.

Well spotted, i never even noticed this, if i reduce the lenght of the room by a foot or two this should solve the problem. I have a structural engineer coming on friday to take a look at the building and my list of questions is 1. Will the existing floor joists support my proposed soundproofing materials? http://www.jamesmmedia.com/controlroom/ ... tail-1.jpg http://www.jamesmmedia.com/controlroom/ ... tail-2.jpg 2. Will the existing rafters support the extra layers of plasterboard I want to install? http://www.jamesmmedia.com/controlroom/ ... -cross.jpg 3. If in either or both cases that extra support is needed, what needs to be installed? 4. Is it safe to add more mass to the existing partition wall and to add another partition wall closely parallel to it? I redid my testing today using the correct settings on my SLM. here are the results The New Test Results Sound Level Meter Settings dBA, slow. Standing in the middle of the attic space with normal everyday sounds, birds, distant traffic, etc the meter read 33.5 dBA. Standing in the room with a drum loop blasting from room below the Attic space @ 92 dBA the meter read 57.3 dBA Will post the outcome of my meeting with the engineer, warm regards hally

Again, great stuff. The questions to the structural engineer look good and complete. The floor design you described is about the best you can do with out spending much more money. Thoughts/budget for doors and windows, if not considered already should be addressed. The level readings are useful. Outside should be fine once the construction is complete. The floor... Personally I reduce the length by at least 2 feet, 10% difference from width. EBU recommendations are 5% difference miniumum.

Thanks Andre, I am spending the day studying my options for doors and window. I am considering a window plug for the existing window but haven't come across any designs for the latter. I thought i might construct it out of glass blocks and wooden frame so as to allow some natural light into the room. I am going to search some more for some designs of such a window plug. Another thought i had was to take 6 feet off the lenght of the room @ the entrance end and make this into a vocal/ acoustic instrument booth which would measure 6 X 12 foot. This would leave the control room 18 X 12 foot. Any thoughts on this idea

Hi Hally, I think the vocal booth is a good idea but would it not be better at the other end, making it easier for people to enter the control room, just a thought. All the best Clunk

Hey hally, Looks great, nice space. I just did the Rod ceiling beef up in my studio and let me tell ya it's a hand full. I'm no expert and if any one doesn't object for some reason i didn't think of, i would much rather fasten the drywall to the subfloor with screws. I did my entire CR with the book mentioned 4D nails, what a nightmare. I think doing it on my own was also a problem. Standing on a ladder supporting the dry wall with my head trying to get the nail hammered appropriately. When i got to the basement i used screws right through the drywall and finished in one day what took me a week and a half the other way. One more important point: Unless you cut the drywall with a laser beam you need 5/8 soft cell backer rod. The specs in the book say 3/8 "Backer rod" not specifying open cell, closed cell or soft cell. I find the 5/8 to be important for variable gap sizes and soft cell is "fool proof". Once again i'm no expert and i would double check any modifications i suggest, but i wish someone told me these things. Check out my thread, it's coming along. http://www.johnlsayers.com/phpBB2/viewtopic.php?t=10665 Good luck!

Thanks Eran, Yea, the CR floor/ room below ceiling will be alot of blood sweat and tears but i'm sure it will be worth it. thanks for the advise and i hope to have a guy to help me with the slabing. I was thinking I might attach the plasterboard between the floor joists with a product we have in ireland that is an adhesive but which remains kind of soft. I will keep the slabs in place until they are stuck with lengths of 2/4 butted up to them from underneath. I think this might help with isolation a little but I'm not really sure. I have ordered 200 meters of 13mm backer rod which as u say should do the trick. I had a look at your post, keep up the good work and i will follow your progress... I lived in New York for a while but never made it out to NJ, great part of the world... regards hally

Eran wrote:

I'm no expert and if any one doesn't object for some reason i didn't think of, i would much rather fasten the drywall to the subfloor with screws.

There is a reason Rod suggest what he does. Though at present, I can't recall the reason; I believe it has to do with all layers of drywall vibrating independently, rather than becoming one large mass.

I figured so, There must be a reason right?! That's why i invited more comments on it. After doing the first floor according to spec i made a decision based on that experience. Hope Rod comments on it... :) jwl said:

I believe it has to do with all layers of drywall vibrating independently, rather than becoming one large mass.

I used only one layer and i kind of think one large mass is good no? Thanks jwl.

Hi all, I had my meeting with the structural engineer on tuesday, i will list his suggestions below... He requested that before he submits his final spec of what needs doing that I settle on a definitive soundproofing plan. His recommendations 1. The floor joists forming the floor of the Control Room/ Attic Space will need to be reinforced with added structural beams below so as to accomadate the added mass which I propose to add between the joists, on top of the joists and on resilient channels below the joists forming the ceiling of the room below which in time will be a drum booth. http://www.jamesmmedia.com/controlroom/ ... tail-1.jpg http://www.jamesmmedia.com/controlroom/ ... tail-2.jpg Three other structural beams need to be installed in different parts of the building to accomadate the added mass going in, these relate to other rooms which I will be dealing with after the CR is completed. 2. The partition wall, http://www.jamesmmedia.com/controlroom/ ... e-room.jpg as it stands would not pass the building regs. now in Ireland as it is insufficient as a structural stud wall, however by adding the second wall behind as proposed in my soundproffing plan this issue will be settled and the roof/ rafters will be properly suported. http://www.jamesmmedia.com/controlroom/ ... detail.jpg (I am sure it is in ur book but what is the suggested distance between these 2 stud walls). 3. A firewindow needs to replace the existing window or else the fire officer will shut me down. http://www.jamesmmedia.com/controlroom/ ... e-view.jpg 4. Depending on my decision on how to treat the ceiling of the attic space which I am still very confused about, another beam might need to be installed along the apex of the ceiling (spanning the lenght of the room 24f) to support the added mass going onto and in between the rafters. http://www.jamesmmedia.com/controlroom/ ... detail.jpg My proposed treatment of the ceiling... http://www.jamesmmedia.com/controlroom/ ... -cross.jpg A thought struck me with regard to the ceiling, my only aim with the ceiling is to restrict external noise from entering the room, unlike the floor where i will be trying to attenuate the sound of drums from below. For this reason maybe I will need less treatment on the ceiling... just a thought The estimated cost for this additional work will be €5000 - €7000 including his fees... SO, thats alot of extra cash but so be it, it needs to be done and done properly. My questions relating to the ceiling, am I approaching this correctly or am i way of the beam (i like it). Will less mass work here? After the fire window is installed, i will need to construct a hinged window plug, can anyone direct me to plans for such a thing... what the theory behind these designs? On the existing blockwalls, http://www.jamesmmedia.com/controlroom/ ... e-view.jpg will it be ok to slab directly onto them or should i use studs connected to the block wall... Thanks in advance and any other observations very welcome warm regards hally