Reducing external noise into my studio

[BaseApe]

Hi guys,

I have set up a room in a shared factory to record music in. The recording is mostly done after hours and on weekends which worked perfectly until recently when the landlord decided to allow several woodworkers to set up shop in the adjoining room. These guys use a lot of machinery - drills, electric saws etc. So, what was once a very quiet environment has now become too noisy for me to record in. Before I take the plunge and move to a new location, I wanted to ask the folks on here what sort of noise reduction measures I can take and how effective they might be.

The room is 4.2 metres wide by 7 metres long. It has a mezzanine which is 3 metres from the floor and that runs from the entrance of the room til about halfway down the length of the room. The ceiling is arched with a maximum height of 6 metres going down to about 3.5 metres at the end of the room. Here are some photos (I have included a photo of the wall in question taken from the adjoining room):-

This is the roof and front of the mezzanine.

roof.JPG

This is the wall which is shared between the two rooms.

room.JPG

Another angle on the same wall.

wall1.JPG

The wall as viewed from the adjoining room.

other room.JPG

The walls are plasterboard that is 1 centimetre thick. There are two layers of plasterboard, one on each side of the frame. There is nothing between each layer of plasterboard ie. no insulation or anything. Just air.

As you can see from the photos, the roof is corrugated metal and there is a large sunlight in the room as well as two clear sheets of plastic roofing to allow light to enter.

I have taken some measurements at dBA to determine what level of sound reduction is currently being seen. Measured from the central point inside the rectangle which represents my room, when the sound source inside the room gives a reading of 87dB, at point 1 in the adjoining room, the reading is 55dB. This point is about 4 metres from the sound source and there is only the plasterboard wall between the two points.

Point 2 represents a point just outside the door of the room which is about 2 metres from the sound source. With the door closed, the reading here is 67dB. With the door open, the reading is 77dB.

room readings.JPG

So, I would like to ask what sorts of treatments people would recommend I make to the room and what results I can expect. At the moment, I have the following ideas in mind:-

1. Plasterboard on the roof with insulation to remove external noise and also noise from the adjoining room.
2. An extra layer of plasterboard on either side of the wall.
3. Build another wall inside the other room, possibly with insulation or other materials.
4. On my side of the wall, perhaps put up a large and heavy theatre curtain. This would be both for appearance and also sound deadening. Behind that I could attach other kinds of materials to the wall to reduce sound coming in eg. carpet.

I should state that my goal is not to make the room into a pristine recording environment. I realise that is not possible. I mainly record rock bands in the room and I am usually recording the band live with overdubs as necessary. Nevertheless, the noise at the moment is quite distracting and a reduction of 10dB or more would be very useful. I am prepared to spend up to $2,000 and put in whatever time is necessary to try and achieve this.

Most grateful for your thoughts.

Simon

[BaseApe]

Ok, I've had a chance to read around more in some other threads. Heaps of great information to be had. I can see it's going to take a while to fully understand all this stuff but I'm happy to invest the time.

I think I can now be a litte clearer with my questions.

1. The far wall of my room is brick and the other three walls are a typical frame with a layer of plasterboard on either side. Am I correct in saying that the plaster walls are 2 leaf while the brick wall and roof are 1 leaf? Will I see benefits from making the roof into a 2 leaf setup by attaching plasterboard to the joists?

2. The walls appear to be quite well done and I can see no obvious weaknesses. However, the roof has some small holes and is not airtight where it meets the brick wall. Would I benefit from making this airtight?

3. The plasterboard is 10mm thick. I have read in other threads that this is too thin and around 15mm would be better. Can I simply attach another layer of plasterboard, perhaps with Green Glue, to the existing plasterboard?

4. There is no insulation in the walls. Another option would be for me to tear down one of the plasterboard layers, put in insulation and then put up new and thicker plasterboard. What do you think of this idea?

5. In my dBA measurements above, I recorded a 30dB difference from the sound source in my room to the measurement point in the next room. Is this actually a valid measurement of transmission loss? Any measurement that is four metres away from the source will be lower by simple virtue of being four metres away! What level of transmission loss do I say my current wall has?

Really grateful for any replies.

Cheers,
Simon

[xSpace]

My thinking is that you have to decide "how bad do you want it". And then set a budget accordingly. You could spend lots of time and money doing a remove and re-install on the walls adding mass and insulation...but if it is a single framed wall assembly you will only get so much attenuation since you can only add so much weight to these walls before they potentially become unstable.

But that isn't the biggest concern for me. That roof sucks Sound is like a balloon and as it moves it expands and according to frequency goes around, under and thru whatever is in front of it. And then there are flanking paths which you guys share plenty of.

And I have to assume a shared slab? All the machinery in the next room, the tables, benches and legs of whatever is being drill pressed or drilled or fastened with a nail gun, table saws, et al...right down the contact point and into the slab and right into your room.

And if you share any duct work with the building....you have to take that into consideration as it needs to be modified to decouple it from everyone else.

[xSpace]

"Any measurement that is four metres away from the source will be lower by simple virtue of being four metres away!"

With every doubling of distance from the sound source, sound is attenuated (drops) 6 dB.

[Soundman2020]

Hi Simon., and welcome!

The far wall of my room is brick and the other three walls are a typical frame with a layer of plasterboard on either side. Am I correct in saying that the plaster walls are 2 leaf while the brick wall and roof are 1 leaf?

Yep! More correctly, the existing drywall walls are "coupled two-leaf" walls, since the studs directly connect the drywall on one side with the drywall on the other.

However, the roof has some small holes and is not airtight where it meets the brick wall. Would I benefit from making this airtight?

Yes. And by adding more mass, too!

3. The plasterboard is 10mm thick. I have read in other threads that this is too thin and around 15mm would be better. Can I simply attach another layer of plasterboard, perhaps with Green Glue, to the existing plasterboard?

You can, but it will not be as effective as replacing that with 15mm, then adding a second layer of 15mm.

4. There is no insulation in the walls. Another option would be for me to tear down one of the plasterboard layers, put in insulation and then put up new and thicker plasterboard. What do you think of this idea?

Absolutely, yes! Insulation increases isolation considerably.

But if you just put drywall back on the existing studs, and they already have drywall on the other side, you will never get good isolation because the two sides of the wall remain coupled, through the studs. If you want GOOD isolation, then you have to decouple.

In my dBA measurements above, I recorded a 30dB difference from the sound source in my room to the measurement point in the next room. Is this actually a valid measurement of transmission loss?

Well, yes, sort of. You should measure with C weighting to be more accurate for loud music. And 30 dB is roughly correct for an average house wall: it wont improve much beyond that until you decouple.

What level of transmission loss do I say my current wall has?

About 30 dBA. But once again, it would be better to measure with C weighting, not A weighting, and also use slow response, not fast. And use loud music with heavy bass and beat, and played over full-range speakers to do the measurements. Ordinary speech, or using a radio or TV is not much use. Also, standard measuring distance is 1 meter form the wall, so that's where you should measure. As Brien said, it should drop by about 6 dB at 2m, and then again at 4m, in free air. But if there are other large things around, then the decrease will be less that that. For example, proximity to the wall itself, and the ground, could reduce that to a decrease of maybe only 2 or 3 dB at 2m, and another 3 or 4 at 4m.


- Stuart -

[BaseApe]

Thanks a lot Stuart and Brien! Really appreciate the feedback.

Brien - in answer to your question "how bad do I want it?' That is something I have been racking my brain about for a couple of months now! The current decision I am facing is probably the most complicated I have ever had to make. It literally touches all aspects of my life. Who knows, once I am finished cursing the woodworkers, I may actually be grateful to them!

There are two main reasons for me to stay put - price and location. The building is located in the inner city of Melbourne in a very cool part of town and the price I pay is very low (although it's low precisely cos the building is shared and that is also the source of my problem!). For me to lease my own premises would involve tens of thousands of dollars more in rent than I currently pay and I would have to settle for an inferior location. In addition, one big advantage of where I am is that I do not have to worry about noise leaking out of the room or the building. There are no residential neighbours in the area who will complain. If I was even 100 metres further east on the exact same street, I would not have that luxury.

Given that I am mostly recording rock bands, the external noise is not normally a problem until it comes time to track the vocals. So, I think I can settle on a short-term goal of having a quiet enough space for vocals. I am considering a vocal booth, but the room is already quite small and the vocal booth itself would have to be very small.

So, taking on board what I have read and what you guys have further clarified, I have a new idea where I partition the room starting at the bottom of the mezzanine. Here's a couple of pics to clarify what I am looking at:-

under mezzanine right.JPG

under mezzanine left.JPG

The space under the mezzanine is 4 metres (L) x 4.2 metres (W) x 3 metres (H)

I am thinking of using accordion doors to create the partition. Here's the steps I am thinking are involved:-
1. Have the accordion doors installed. I have read on the manufacturers website that their doors are rated at up to 40 STC
2. Remove the plasterboard from the areas of wall under the mezzanine on my side of the frame
3. Build a second frame next to the existing frame (taking on board Stuart's point about decoupling)
4. Add insulation
5. Add two layers of 15mm plasterboard (with Green Glue?) to inner side of the new frame

I guess this idea is really just a 'room within a room', right?

The advantages I can think of for this idea are that it removes my need to deal with that sucky corrugated metal roof It will also give me some flexibility in configuring the room overall.

Where I am unsure is how to incorporate the roof/floor of the mezzanine in to this idea.

What do you think of this approach?
Would accordion doors rated at 40 STC give me isolation even though they are only 1 leaf?
Is it worth building the second frame?
Should I also build a new ceiling for this space at the same time? (the mezzanine is 3 metres off the ground so I don't mind losing height if I gain isolation)

As always, grateful for your thoughts.

Cheers,
Simon

[xSpace]

If you are going to build a true "room in a room" then you have several things to consider in respect to this environment. I mean, the fundamentals are used in every build but the specific application I am going to discuss only applies to your unique situation.

Ideally (ideally right ) you want to have as consistent a mass barrier as is humanly possible on both sides of the wall/wall, ceiling/roof.

In order for you to achieve something like this you would, ideally, remove the mass from the interior side of your room as it is right now. If this mass is removed with care it can be used to mass up the other side, the side that is now what you are looking at IF you removed the interior side and that will be the back side of the mass of the offending persons room.

Budgets are in place for a reason. The reason is that this is a base amount that you are willing to spend knowing in the back of your head, you will spend several times more than that. It is the nature of the beast.

The challenge with a true room in a room in your situation is that the roof is a big hole. BUT distance as we are already seeing can be a friend in this respect in that sound does reduce with distance. This may be a key event for you. I would still look up and recognize that this overhead area has to be modified with mass in some form to mitigate the potential issue of leakage.

But when you frame this interior, yes, you have to put a lid on it, the ceiling. This is what makes it a true room in a room fully decoupled environment.

I would opt for a solid core door with the proper framing and air sealing rather then a door that is speced at 40 STC. Frankly, I installed lead on my solid core door, but it ain't for everyone.

But if you are going to get leaks it will be at the window/door and HVAC vent areas. Walls are easy, but the doors/windows and HVAC those can be a pain at least until you understand what decoupled means and then it becomes a mission...which maybe why I get so side tracked with hammering that home with other persons (not you my friend) who never seem to get it

And then you use as much floor space and as much height as possible...volume is a gift to sound waves and gives many blessings in return when given the maximum you can.

[BaseApe]

Thanks again, Brien.

I've been mulling over your comments for a few days. I also called around to get some quotes for accordion doors and it looks like I'd blow my entire budget on those alone. Of course, four heavy doors for a room within a room setup would probably cost about the same. I'm also reluctant to reduce the dimensions of the room any further than what they already are. So, I've been thinking of perhaps my last option - the mezzanine! Here's some pics:-

The door of the mezzanine:-

mezzanine door.JPG

From the top of the stairs:-

mezzanine inner.JPG

Inside to the left:-

inner left.JPG

Inside to the right:-

inner right.JPG

As you may have noticed, I'm using the mezzanine as a control and mixing room, so improving its isolation would be good in general, but it's also a potentially good room for vocal tracking. I have already put up insulation on the roof and inner wall and boarded those up with MDF. This makes the room a coupled 2 leaf except for the floor which is a single leaf. So, here's how I'm thinking about this idea:-

1. Put insulation between the joists under the mezzanine floor and add a second layer of plasterboard to make it 2 leaf.
2. Currently I have a hollow core door on the mezzanine but I read a nice little trick in this thread (http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1662) about making that work for me. So, maybe implement that and seal around the door.
3. There are two gaps in the walls currently 1) the extraction fan on the left wall 2) a small 'chimney' in the ceiling. I like the idea of somehow using the chimney to bring in fresh air although I don't really know how I would do that at the moment. I'd probably remove the extraction fan and board up over that.

Brien, I'm curious about your somewhat cryptic remark about decoupling in relation to doors and HVAC. Could you elaborate? In particular, I can think of three ways to attack the mezzanine idea:-

1) Pull out the inner layer of the existing plasterboard, add insulation and then board over that again (leaving the MDF on the roof and inner wall). This would give me a coupled 2 leaf set up with insulation all round. This seems to me to be the easiest option.
2) Leave the current walls as they are and add a third leaf by building the new frame inside the existing walls and insulating between that and the existing inner wall. I've read that 3 leaf is a problem for bass isolation but most of my noise troubles are in the mids so bass is not really a problem for me.
3) Decouple by removing the inner leaf that currently exists, building a new frame and adding insulation and plasterboard to that.

What do you think about these three ideas and the mezzanine idea in general?

Cheers,
Simon

[xSpace]

"Brien, I'm curious about your somewhat cryptic remark about decoupling in relation to doors and HVAC. Could you elaborate? "

Not cryptic at all, the idea has to gel and then it will be more clear.

Keep in mind we are still discussing an accurate room-in-a-room. To achieve the highest possible TL (transmission loss) the interior side of the room has to be decoupled (not attached) to the exterior. In reference to doors, this suggests two doors, one on the interior and one on the exterior. So these 2 doors do not connect they are decoupled one from the other.

HVAC will carry as much noise as can fit into the passage so you decouple that as well. As a matter of potential airborne sound issues, air inlets and outlets are placed on opposite sides of rooms, one higher and one lower IF at all possible. But even the ductwork has to be decoupled, not connected, from the interior side of the build to the exterior side of the build. So you develop "baffles, usually of MDF or another mass laden material, lined with insulation with breaks in the air travel path to prevent sound from having a "direct" path into or out of the room.

[BaseApe]

Ok, I think I've more or less got you, Brien. Been spending the last days reading up on HVAC related topics, which was an issue I was needing to address sooner or later anyway.

Just a question on decoupling with relation to the mezzanine. The floor of the mezzanine is coupled to the walls. If I were to build a room within the mezzanine, would I need to have a decoupled floor also?

[xSpace]

The floor of the mezzanine is coupled to the walls. If I were to build a room within the mezzanine, would I need to have a decoupled floor also?

The structure would not support it so the answer has to be No. In order to build a proper decoupled floor you have to consider that you are still doing a mass/spring system so the first mass has to match or exceed the second mass. In this case the first mass is light weight building materials and you will never fully decouple that from the existing structure so it is always better to simply add that mass directly to the floor rather than attempt a wooden frame diaphragm that will simply resonate like a drum head.

Several things that would need to be considered, one being adding mass to the floor, insulation to the underside of the joists and adding mass to the bottom side of the joists.

You can click here for http://sketchup.google.com/3dwarehouse/ ... 541410f02a "drum riser sketchup" and get some results. What this is basically is to damp the floor using 703 panels with 3/4 inch plywood on top of the 703 to break/damp the path of sound transmission moving from the existing floor/flanking path.

[BaseApe]

Thanks again, Brian. Really appreciate your feedback. I've been away for a while digesting all this new info and thinking about the way forward.

I think massing up the floor of the mezzanine will be fairly straightforward. I already have insulation between the joists for most of area. I guess I would just board up over the joists from underneath and maybe add an extra layer to the existing floor on top.

I'm thinking the easiest option for me in the mezzanine will be to simply build new walls and ceiling within the existing structure. This will result in a 3 leaf system.

Just to reiterate the current status - the roof is the corrugated metal but I have insulated between the joists and boarded over with MDF. The walls are the two layers of 10mm plasterboard on either side of the frame with no insulation between. The floor will also eventually be 2 leaf once I do the work to it. Thus, a 2 leaf system.

I'm thinking I put up another frame, insulate between that frame and the existing walls/ceiling and then plasterboard the inner side of the frame making a 3 leaf system.

Any thoughts on this idea?

Would I benefit much from removing the inner layer of plasterboard from the existing walls, insulating and then replacing? That would mean I would have fully insulated the existing two leaf structure before adding the third leaf.

[xSpace]

"I'm thinking I put up another frame, insulate between that frame and the existing walls/ceiling and then plasterboard the inner side of the frame making a 3 leaf system."

Why are you wanting to construct a 3 leaf...this is not the way to go.?

[BaseApe]

Hey Brien,

The main benefit I can see is that it saves time and effort to remove the existing plasterboard.

I'm happy to be dissuaded though From readings on other threads I got the impression that, while inefficient, a 3 leaf structure does provide extra isolation in the mids but reduces bass isolation. Is that not correct?

[herlinwilson]

I also faced this kind of problem. With that machine sounds, I didn't enjoy the music. Actual, My house roof is made with rubber. Can I change the roof to come out from this problem? If anyone knows the solution, Please share. Any kind of information is greatly accepted.