Small mixing room in Zagreb

[ik01]

Hy guys,

for the first time, I also decided to write a post. I am researching all options for my future mixing room.
It is small. Not possible to change this. 295(w) x 450 cm (l) x 260cm (h).
Room is in residential building, 2nd floor... So I will try to give as much technical data as possible...
Walls betwin 2 appartments are 20cm reinforced concrete.
Outher walls are constructed of 20 cm thick reinforced concrete, 10 cm thick expanded polystiren...
Building has floating floors on 20 cm thick reinforced concrete (2 cm of expanded polystiren, 6-8 cm of screed, parquet, flooring..).
I am not shure does buildings energy certificate says anything about sound isolation. What I do know is, similar materials sometimes overlap when trying to do termic or sound isolation. My building has B certificate (27 kWh/ (m2a)). Again, not shure how relevant it is, but since I have this measure too, I decide to share it

Well as you can see, my future mixing room will have priority to be well isolated. At this point I am not thinking about acoustic, but, whole idea is to project room that in phase 1 (sound isolation, wooden frames, drywalls...) has good shape wich ensures less drastic acoustical intervention in later phaze... And yes, sound isolation is very important, but I am not going to have extremly loud sound sources such as drums or bass amps etc. just a pair of 2-way monitor speakers ..

Neighbours: above, belowe and on the right side...

So, lets start with my idea what was I planing to do. I know forum's experts will know exactly what is good, bad and completly wrong with my idea.
as you can see on a blueprint, window in front of listening position is off center position. I do not have problems with that, but soffit is not the way to go here. I have really hi quality speaker stands ( 3 square tubes filled with sand, massive upper and lower plates, spike holes on both plates..50 kg each weight), and they will do the job. I also had idea to construct 2 resilient platforms for each stand with speakers to prevent vibration transmissions thru stands to the floor..

door (back of the listening position) will be changed to PVC door with double iso-glass surface.

Radiator will be removed, pipes closed and isolated, and they will be behind double drywall (2x 1.5 cm, inter layer Green Glue). Instead of radiator, I plan to put AC unit with heating option.

Plan is to put another window ( a little bit biger than original one, so both can be opened. this one will be mounted on new wall's construction..)

My plan is to build wooden frames out of 5 x 8 cm battens (kinda standard measures here..). since floor has floating construction, I guess it is only possible contact surface (no direct contact with bearing walls or horizontal concrete surfaces..) . So whole inner construction for new room will be wooden cage on a resilient self adhesive foam tape...Ceiling construction will be build later and it will practicly lay down on side constructions, filled with same 50kg/m3 mineral wool wich will be used for all other walls aswell.

so far I am not shure if I need to do any additional floor construction (since room has floating floor anyway), but any advice there is wellcome...As far as I learned reading this forum, it is better not to do it at all than to construct it wrong.

is dual drywall with Green glue also necessaire on ceiling construction to prevent sound leakage, and is wooden cage sufficient for such weight in case it is?

Should I think in a way to get rid of some parallel sides ( especially front part, to get less reflection in mixing position). If i decide to do such shape on walls or maybe ceiling construction, should it be filled with some kind of hangers to absorb possible LF rumbles?
There is no resilient channels to buy in Croatia. Do I need to mount drywall strictly on resilient chanel or it will be overkill for my room?

How loud do I monitor.... Well, maybe 85 dB when critical listening with some bass heawy electronic pieces would be absolute maximum for me. 75-80 dB are probably average levels.

Budget is arround 1500-2000 EUR for isolation, walls and door/window. At this point I try not to involve any acoustic investment.
Thanx for any good advice, or correction of bad ideas

Ivan

[stevev]

Hi Ivan, nice post and I'll answer as many questions as I can

Hy guys,

for the first time, I also decided to write a post. I am researching all options for my future mixing room.
It is small. Not possible to change this. 295(w) x 450 cm (l) x 260cm (h).
Room is in residential building, 2nd floor... So I will try to give as much technical data as possible...
Walls betwin 2 appartments are 20cm reinforced concrete.

-----20cm of concrete is fanstastic isolation, that's really good news!!! I don't have the actual numbers, but I would think that might get you 40db of transmission loss by itself.

Outher walls are constructed of 20 cm thick reinforced concrete, 10 cm thick expanded polystiren...

-----hmmm....is the 10cm expanded polystyrene a wall by itself or is it in front of the 20cm thick concrete wall?

Building has floating floors on 20 cm thick reinforced concrete (2 cm of expanded polystiren, 6-8 cm of screed, parquet, flooring..).

-----again, the concrete is great news for isolation, although the floating parquet may give you some resonance issues inside the room.

I am not shure does buildings energy certificate says anything about sound isolation. What I do know is, similar materials sometimes overlap when trying to do termic or sound isolation. My building has B certificate (27 kWh/ (m2a)). Again, not shure how relevant it is, but since I have this measure too, I decide to share it

Well as you can see, my future mixing room will have priority to be well isolated. At this point I am not thinking about acoustic, but, whole idea is to project room that in phase 1 (sound isolation, wooden frames, drywalls...) has good shape wich ensures less drastic acoustical intervention in later phaze... And yes, sound isolation is very important, but I am not going to have extremly loud sound sources such as drums or bass amps etc. just a pair of 2-way monitor speakers ..

Neighbours: above, belowe and on the right side...

So, lets start with my idea what was I planing to do. I know forum's experts will know exactly what is good, bad and completly wrong with my idea.
as you can see on a blueprint, window in front of listening position is off center position. I do not have problems with that, but soffit is not the way to go here.

-----The big issue is that the window will lower your isolation considerably. It's the weakest point as it's only a pane of glass compared to the 20cm thick concrete wall around it. You'll have to plug that window with quite a lot of mass to get the same kind of isolation your getting with the rest ofthe wall.

I have really hi quality speaker stands ( 3 square tubes filled with sand, massive upper and lower plates, spike holes on both plates..50 kg each weight), and they will do the job. I also had idea to construct 2 resilient platforms for each stand with speakers to prevent vibration transmissions thru stands to the floor..

-----The platforms sound like a good idea, although I don't have enought knowledge in that area to say whether it's a good or bad idea.

door (back of the listening position) will be changed to PVC door with double iso-glass surface.

-----If you're doing a 'room within a room' construction, which is what it sounds like you'll be doing, then you'll need two doors. The existing one which is in the wall of your outer leaf, and a second one built in the inner leaf door. If the existing door is solid timber then it may already suit your needs once it's got proper seals around it.


Radiator will be removed, pipes closed and isolated, and they will be behind double drywall (2x 1.5 cm, inter layer Green Glue). Instead of radiator, I plan to put AC unit with heating option.

-----Sounds good, although mounting AC through 20 cm thick concrete will be a challenge

Plan is to put another window ( a little bit biger than original one, so both can be opened. this one will be mounted on new wall's construction..)

-----Again, this is where your weak point is as far as isolation goes and not having a window at all would be the best option for your isolation needs.

My plan is to build wooden frames out of 5 x 8 cm battens (kinda standard measures here..). since floor has floating construction, I guess it is only possible contact surface (no direct contact with bearing walls or horizontal concrete surfaces..) . So whole inner construction for new room will be wooden cage on a resilient self adhesive foam tape.

-----that sounds correct, but leave out the foam tape unless the floor is very uneven. A properly applied bead of acoustic sealant during construction will do the job.

..Ceiling construction will be build later and it will practicly lay down on side constructions, filled with same 50kg/m3 mineral wool wich will be used for all other walls aswell.

-----correct.

so far I am not shure if I need to do any additional floor construction (since room has floating floor anyway), but any advice there is wellcome...As far as I learned reading this forum, it is better not to do it at all than to construct it wrong.

-----again, correct and you read right

is dual drywall with Green glue also necessaire on ceiling construction to prevent sound leakage, and is wooden cage sufficient for such weight in case it is?

-----If that is how you are building the rest of your internal walls then yes. Think of the ceiling as just another wall, they all have to be built the same. However, as far as the timber construction goes it will have to be heavier timber than your walls because it is a hanging weight. This is where you need a qualified builder, or engineer to advise you on loads etc. It may be possible to use a laminated type of beam so your construction doesn't take up valuable ceiling space, but again, you need someone with the right knowledge for your location to tell you about this.



Should I think in a way to get rid of some parallel sides ( especially front part, to get less reflection in mixing position).

-----At this point, I believe the answer is no. You'll deal with the acoustic treatment of the space once you've finished the isolation part. Having said that, hopefully someone with more knowledge about room geometry will be able to give you a better answer. It may indeed be a better idea to take part of the inner leaf construction 'out of square' given that you have limited room to work with and aren't soffit mounting your monitors.


If i decide to do such shape on walls or maybe ceiling construction, should it be filled with some kind of hangers to absorb possible LF rumbles?

-----you'll definitely have to have some kind of absorbing materials on the inside of your inner leaf. It's also one of the reasons John suggests 'inside out' construction for walls and ceilings as it means you can use the cavity to fill with acoustic treatment which also saves valuable room space in small areas like yours. Definitly worth considering for this build and it's outlined in John's manual.


There is no resilient channels to buy in Croatia. Do I need to mount drywall strictly on resilient chanel or it will be overkill for my room?

-----no need for RC unless you were going to mount ithe drywall directly to the concrete.

How loud do I monitor.... Well, maybe 85 dB when critical listening with some bass heawy electronic pieces would be absolute maximum for me. 75-80 dB are probably average levels.

Budget is arround 1500-2000 EUR for isolation, walls and door/window. At this point I try not to involve any acoustic investment.

-----I think you might be underestimating a bit there, but i'm not really sure of material prices where you are and how much of this build you are giong to be able to do yourself. If you're hiring any contractors, which you'll need for electrical and AC, then I think you're way under budget, sorry

Thanx for any good advice, or correction of bad ideas


-----no problem, that's why the forum is here and good idea posting up before you've started any construction. Getting all your planning done before you pick up a hammer is the key point in building a studio. Maybe post up a few pics if you're able to to give us a better idea of what the space looks like.

cheers,

Steve

[ik01]

first, Steve, thanx for your fast and detailed reply

Outher walls are constructed of 20 cm thick reinforced concrete, 10 cm thick expanded polystiren...

-----hmmm....is the 10cm expanded polystyrene a wall by itself or is it in front of the 20cm thick concrete wall?


it is outer thermic isolation. So from inside out it is 20 cm of reinforced concrete, then polystirene.and I guess facade materials covers polystirene (i guess last layer can not help with isolation)


-----again, the concrete is great news for isolation, although the floating parquet may give you some resonance issues inside the room.

if you think on parquet as a reflective glossy surface, I guess it is exactly like that. I forgot to write, I plan to cover it with some thick carpet.


-----The big issue is that the window will lower your isolation considerably. It's the weakest point as it's only a pane of glass compared to the 20cm thick concrete wall around it. You'll have to plug that window with quite a lot of mass to get the same kind of isolation your getting with the rest ofthe wall.


Exactly my fear of sound leakage. You see, this room has 3 weak points: Window, door and radiator pipes. I hope closing pipes, isolating with some foam tubes, or even little sandbags, and leave them behind inner leaf can do the job. I can easily include 2 same doors, each on separete side of wall, but need to find practical solution ti prevent any contact betwin innet and outer walls. This may be tricky even more with windows (i can not imagine hole betwin two windows, and any other solution can be some kind of contact betwin leafs.)


-----The platforms sound like a good idea, although I don't have enought knowledge in that area to say whether it's a good or bad idea.


same here. Since my speakers are only source of vibration and sound, I guess eliminating vibration would leave me with only one problem : direct sound. Fighting with dBs looks like something you just can not avoid here, but direct vibrations transmission is something lot easyer to solve. I guess old Hi fi magic tricks such as speaker spiker or Blue tack are out of the question (in theory whole vibration ftom boxes and stands should be transformed into thermic energy at the peaks of spikes, but in practice they can also help to transmit energy to lower layers of the floor...). I am on very thin ice here )


-----Sounds good, although mounting AC through 20 cm thick concrete will be a challenge


I plan to put split system AC, so one hole for instalations will do the job


----Again, this is where your weak point is as far as isolation goes and not having a window at all would be the best option for your isolation needs.


It is a window on outer wall. The one that faces street. I can't close it, so probably solution one window per leaf would be optimal. Unfortunally, things are in most cases only optimal..


-----that sounds correct, but leave out the foam tape unless the floor is very uneven. A properly applied bead of acoustic sealant during construction will do the job.

Floor is OK. maybe to find right acoustic sealent is more problematic part here. If i go to Green glue sealent, I could easily break mz budget fast. Anyway, Green glue compound will take pretty big bite since I need 2 boxes for this room... If you have any suggestion for acoustic sealent products that can do job better than foam tape, and cost less than green glue's sealent, please let me know.


-----If that is how you are building the rest of your internal walls then yes. Think of the ceiling as just another wall, they all have to be built the same. However, as far as the timber construction goes it will have to be heavier timber than your walls because it is a hanging weight. This is where you need a qualified builder, or engineer to advise you on loads etc. It may be possible to use a laminated type of beam so your construction doesn't take up valuable ceiling space, but again, you need someone with the right knowledge for your location to tell you about this.


I do not know any qualified builder arround here, but I gonna research. Studio construction is as far as I experienced, extremly complex way of thinking. Most of local builders know how to build wall and paint it. I just can not afford fast ways to get materials destroyed. When I did my old studio, builders without any practical experience with studio projects, did all possible mistakes they could. I will probably hire one experienced guy to help me with framing, and everything else (except electricity and AC) I will do by myself with help from few friends (also in studio busyness). Since I am in the middle of buying this place, I will not be in a hurry, so will do it step by step with as much as possible soundproof wise details in mind.


-----At this point, I believe the answer is no. You'll deal with the acoustic treatment of the space once you've finished the isolation part. Having said that, hopefully someone with more knowledge about room geometry will be able to give you a better answer. It may indeed be a better idea to take part of the inner leaf construction 'out of square' given that you have limited room to work with and aren't soffit mounting your monitors.


I am looking forward. I know this forum is "the place to be" for such problems, and so far I saw countless projects perfectly finished with help of few extremly specialised guys. I hope compare to those high end studios, my dilemmas would look pretty simple and easy to solve .


-----you'll definitely have to have some kind of absorbing materials on the inside of your inner leaf. It's also one of the reasons John suggests 'inside out' construction for walls and ceilings as it means you can use the cavity to fill with acoustic treatment which also saves valuable room space in small areas like yours. Definitly worth considering for this build and it's outlined in John's manual.


My plan is to fill frames (cavitys of 1000 x 600 mm exact as mineral wool in blocks..) with 45-55 kg/m3 mineral wool (depends on what i find), about 8-10 cm thick. Whole framing shoud be covered. Walls and ceiling... later I even plan to cover mineral wool before any inner walls mounting. will definitly search forum to find out more about this. If you know about exact topic, feel free to post me link.


-----no need for RC unless you were going to mount ithe drywall directly to the concrete.


it is a great news. more savings


Budget is arround 1500-2000 EUR for isolation, walls and door/window. At this point I try not to involve any acoustic investment.

-----I think you might be underestimating a bit there, but i'm not really sure of material prices where you are and how much of this build you are giong to be able to do yourself. If you're hiring any contractors, which you'll need for electrical and AC, then I think you're way under budget, sorry

well, you have what you have. I planned one budget, but at this point I can not be shure i won't brake it . Contractors for AC and electrical stuff are must, but different standard arround here and "guys i know" can make it much cheaper than in western Europe, USA, Canada, Australia...Planed budget does not include Green Glue. I will buy two boxes before i even move to new place. Other materials are not so expensive. Most of the tools I have anyway. AC unit and door/window for inner leaf are most expensive parts. .Most important part is, I am gonna do most of the job by myself, and with help of few friends whose fee will be beer, few steaks and help back when needed


-----no problem, that's why the forum is here and good idea posting up before you've started any construction. Getting all your planning done before you pick up a hammer is the key point in building a studio. Maybe post up a few pics if you're able to to give us a better idea of what the space looks like.


I will do that as soon as I visit tha place again. I am still not the owner of the place. Just payed advance untill I sell my recent appartment. So from this point i feel like planing right now, before moving is way to go. Things are going to look hectic anyway when I start with hammering.

Thanx again Steve. you solved some of my dillemas.

Ivan

[ik01]

Another detail; I read here on John Sayers about good experiences with OSB - Green Glue - sheetrock. I belive this may be "way to go for me". It looks like real problem detecting studs to hang acoustic elements in later steps. Any experiences with this? I understand lower densitys of OSB compare to Sheetrock. Should it be compensated with thickness?


Ivan

[stevev]

Planed budget does not include Green Glue. I will buy two boxes before i even move to new place

I don't have time to reply to the rest of your post at the moment Ivan, but i just saw this bit and think it might be worth holding off on buying the green glue if it's particularly expensive where you are. The 20cm thick concrete will give you some pretty serious isolation as your outer leaf, so you may not need the green glue at all.

I'd wait until you get in to the space and do some transmission loss testing to see exactly how much isolation you need in the real world. This could save you a lot of money in the long run.

cheers,

steve

[ik01]

Planed budget does not include Green Glue. I will buy two boxes before i even move to new place

I don't have time to reply to the rest of your post at the moment Ivan, but i just saw this bit and think it might be worth holding off on buying the green glue if it's particularly expensive where you are. The 20cm thick concrete will give you some pretty serious isolation as your outer leaf, so you may not need the green glue at all.

I'd wait until you get in to the space and do some transmission loss testing to see exactly how much isolation you need in the real world. This could save you a lot of money in the long run.

cheers,

steve

thanx Steve for your help!

Ivan

[ik01]

I have another question related to this topic; On few occasions I have read here on JS forum, recommendation for OSB-GG_Drywall construction. Any practical experiences with this combination? to me it looks like perfect way to achieve more rigid construction and, more important, easyer solution for later hanging stuff on the wall (it is not easy to detect wooden grill under 2 leafs of drywall. OSB looks like legent solution fot lighter elements. If I miss wooden frame, nothing bad will happen ).
what about thickness in such combination. Drywall boards will be 15mm thick. should OSB be thicker than this, or the same thickness will do the job?


Thanx again in advance for every shared experience

Ivan

[stevev]

I have another question related to this topic; On few occasions I have read here on JS forum, recommendation for OSB-GG_Drywall construction. Any practical experiences with this combination?

Whilst I haven't used this combination myself, I do believe other's here have used it and it works. Search around the forum and you'll find someone who has used it. I believe the OSB should be at least as thick as the drywall and probably a little bit thicker is better. I don't think you'd need it to be an inch thick or anything though.

steve

[ik01]

Thanx again Steve! This was really fast, man! I was thinking about 15-18mm thick boards.
When I finish control room once, I will get six pack of Fosters and drink to you mate (as far as I know, probably only australian beer possible to buy here)!
You helped with all of my dilemmas!

Ivan

I have another question related to this topic; On few occasions I have read here on JS forum, recommendation for OSB-GG_Drywall construction. Any practical experiences with this combination?

Whilst I haven't used this combination myself, I do believe other's here have used it and it works. Search around the forum and you'll find someone who has used it. I believe the OSB should be at least as thick as the drywall and probably a little bit thicker is better. I don't think you'd need it to be an inch thick or anything though.

steve

[stevev]

Thanx again Steve! This was really fast, man!

no problem

I was thinking about 15-18mm thick boards.

that sounds right to me.

When I finish control room once, I will get six pack of Fosters and drink to you mate (as far as I know, probably only australian beer possible to buy here)!

let me know when that is and i'll grab a beer and toast to your success