Vent cover on a hinge design help please

[dolomick]

I've got an outdoor shed I want to start working in, but it has vents and I would like to have the option to cover them if I'm working at night and don't want sound leaking outside to the neighbors. I'll be putting cotton or roxul safe'n'sound in between the studs and then drywalling the shed. I was thinking of having my carpenter leave a hole in the drywall where the vent is, and attaching the cutout drywall that is the size of the hole to some hinges above the hole, effectively making a removable plug. Then maybe attaching cement board on top of that and wider than the cutout drywall to cover the seams. Finally, making a pulley system so I can pull the thing open and wrap the rope around a hook in my wall to keep it permanently open when I'm not inside. Would that be reasonably sufficient? Should my second layer of cement board that overlaps the drywall plug have some sort of acoustic weatherstripping or something where it meets the drywall? Thanks for any brainstorming help!

[Soundman2020]

Hi. Please read the forum rules for posting (click here). You seem to be missing a couple of things!

Those vents are there for a purpose: probably to ventilate the underside of your roof deck, and it would be a really bad idea to block that.

Next: You didn't say how much isolation you need, but the method you describe is not going to get you much isolation at all: maybe 30 dB, maximum, and probably less. For a studio, that's probably well short of what you need.

I would suggest that you start by figuring out how much isolation you need, in decibels, then based on that you can look at methods for isolating your building without affecting the roof ventilation.



- Stuart -

[dolomick]

Updated profile, I live in LA. This is a hobby (making music) so my budget to fix the vent is an extra $100 bucks to fix this.

I monitor at 75db and do not want to disturb neighbors at night. Sorry I don't have a sound meter but I would be happy with 25db sound reduction. The project has not started. I think my idea is decent enough to make some sizable dents in SPL, but I want confirmation or improvements on it. I need the ventilation obviously, but in some instances I need to plug it up. Should be easy for the experts around here to devise a cost-effective solution given my parameters I would think.

[Gregwor]

Should be easy for the experts around here to devise a cost-effective solution given my parameters I would think.

Stuart is hands down the best regularly active member (and mod) on the forum. He told you what the vent is there for and you should really consider what he said about it. You should research what happens when you mess with it.
He then asked you to figure out the level of isolation you need. This is pretty much step one in any studio build. You didn't give room dimensions. You didn't state if you will be recording in the space. Will this purely be a mixing/listening room? What is the floor made of? How is it constructed? Do you have power? Do you have HVAC equipment for the room? Are there windows? Is there doors?
These are all things that need to be considered if you want the room to work even the slightest amount. Seriously.
Please respect the professionals like Stuart when they reach out and lend a hand. Do as they ask and you will end up with a great space. All comments (including mine here) will sound harsh, but they're never intended to hurt anyone's feelings. They're only there to make you think about possible problems and solutions so that you don't end up wasting more time and money than necessary.
There are COUNTLESS threads on "sound proofing" rooms here on the thread. Take a few days and search/read the forum. Chances are, you can answer most of your own questions after that.

I think my idea is decent enough to make some sizable dents in SPL

There are lots of formulas posted that can help you figure out what construction methods will give you X amount of isolation. I personally posted a "TL Calculator" excel file. You might want to punch some parameters into that. The number 1 mistake people make is "thinking" their ideas will work. Math and the laws of physics can help you easily determine if your ideas will work. It takes a few minutes to know for sure. So do that and be sure. Stuart just told you that you might get around 20dB of isolation with your current plan (assuming your doors and windows are sealed up well). To put that into perspective, a standard foamy ear plug gives you around 30dB of isolation. That isn't much.

Greg

[dolomick]

You didn't give room dimensions. You didn't state if you will be recording in the space. Will this purely be a mixing/listening room? What is the floor made of? How is it constructed? Do you have power? Do you have HVAC equipment for the room? Are there windows? Is there doors?

You make a valid point on room dimensions, sorry I forgot to mention it's 8'x10' (far from ideal I know, it's quite tiny). I don't know about floors yet as I haven't decided - remember I stated the project hasn't started. The floors are mdf I think or something similar, I am not handy so I don't know. There will be power, there won't be recording going on. The vent is the most important sound leakage area as it's literally a hole in the wall! (which is why I am starting with that). The door will be the next most obvious area to start - and yes of course there is a door to enter the shed. There is a window too but I will be getting a plug for it from http://www.soundproofing.org/

You should research what happens when you mess with it.

Jeez - there's an clear inference there that I have not, which is false. It's got a window, I can open it if need be to get some fresh air and use headphones for 10 minutes. The reason for these forums is so people can share their knowledge. Maybe instead of cryptically alluding to something really bad happening, you could just plainly state your concern?

There are COUNTLESS threads on "sound proofing" rooms here on the thread. Take a few days and search/read the forum. Chances are, you can answer most of your own questions after that.

I am asking a very specific question about my vent and was not asking multiple obvious questions about general soundproofing.

The number 1 mistake people make is "thinking" their ideas will work.

Hence the whole entire point of why I posted my question - for brainstorming ideas or improvements onto the execution of my idea. I already searched the reference area littered with links. I already read many posts.

The common theme of threads on this site seems to be asking for tons of info and then telling people that their idea will be ineffective - obviously the way sound works it's going to leak/flange through the weakest link so I understand why that theme emerges, but it would have been nice to just get a specific answer related to my specific vent question. It would be actually possible to speak about my vent issue without addressing the doors, windows, room size, etc. - assume the shed interior is hermetically sealed and then address the vent question, for example. Just sayin'.

[Gregwor]

I am asking a very specific question about my vent

The vent is there to allow air circulation which if sealed, can cause moisture, mold, rot, etc. Sure, you could make a plug for it, but let's say you forgot to pull the plug every now and then and left it over the weekend each time. Not awesome. I'm sure some other pro construction types can get more specific. The bottom line is that you need fresh air to get into your room, and stale air to get out. All of this without trashing your isolation.

Greg

[Soundman2020]

You make a valid point on room dimensions, sorry I forgot to mention it's 8'x10' (far from ideal I know, it's quite tiny).

Well, it is what it is! There's a saying around here: If that's what you have to work with for your room, then it sure is a hell of a lot better than not having a room at all! It's tiny, yes. Very. And it won't be optimal. But it can still be usable.

there won't be recording going on.

So this is ONLY a control room them. Got it.

The vent is the most important sound leakage area as it's literally a hole in the wall!

And it is a very NECESSARY hole in the wall! That's what you seem to be missing here. You can't just plug it up, not even occasionally, because it is there for a purpose. So you have to deal with it by building a silencer box that will allow the air to flow through while also preventing the sound from getting through.

There is a window too but I will be getting a plug for it

Why? Glass has much higher surface density than either drywall or OSB, so unless the glass is very thin, it will probably provide about the same isolation as the rest of the wall. The key to isolation is mass. In other words, how much does each square foot of the wall weigh. As long as that is consistent across the wall, not changing too much, then the entire wall will isolate to the same level. Assuming that you have something like typical 5mm glass in the window, and 12mm OSB plus some type of siding on the outside, the glass is likely providing more mass than the OSB+siding.

... I will be getting a plug for it from

Ted White (the owner of the soundproofing company) is also a valued and respected member of this forum, who sometimes helps out with questions from other members, when he can. I suspect he would probably agree with what I'm saying here. I also don't think he sells custom-made window plugs. I may be wrong, but in my conversation with Ted, I have always understood that he sells raw materials for isolating rooms, and he also sells many ready-made treatment devices, but I don't recall him saying that he also does custom manufacturing of window plugs.

You should research what happens when you mess with it.

Jeez - there's an clear inference there that I have not, which is false.

Please don't take this the wrong way, but that isn't what we are seeing. I'm sure you think you have done good research on the purpose of that vent, but from our point of view, we can see that you have not. If you had, you would not be asking how to close it up; you would be asking how to stop sound getting through it, which is not the same thing at all.

It's got a window, I can open it if need be to get some fresh air and use headphones for 10 minutes.

Sorry, but no you can't! That's a very common misconception. We hear it all the time, and it simply is not a viable ventilation solution for a studio. Once you have done more research on that, you'll see why.

The reason for these forums is so people can share their knowledge.

That's what we are doing, but you don't seem to be liking it because you are finding out that this is going to be more complicated and more expensive than you originally expected. That happens very often here on the forum: new people arrive with preconceived notions of how sound should work, and how they can easily deal with that based on assumptions and intuition. Unfortunately, sound does NOT act the way people assume it should, and neither is acoustics intuitive. It takes a while to learn enough that you can start to see why this is true. Many people don't bother with that, thinking they can somehow bypass the laws of physics: that there studio will be immune to the laws that govern the entire universe, and that the solution that they came up with really is going to work... even though the people who have studied this and making a living from designing and building studios, are telling them that it won't work. The smart people notice that they are talking to people with experience, who have "been there and done that", and start believing them, taking their words into consideration. The others don't: they insist that they already know enough, and can do things their way, somehow beating the universe in the process.

Maybe instead of cryptically alluding to something really bad happening, you could just plainly state your concern?

I think Greg actually did that, to be honest! Vents have a purpose. The designer who designed the shed based on the building code, and the folks who originally wrote the building code, have a reason why the insisted on having the vent. Closing off a vent into a habitable space is not only a bad idea, it is probably also illegal, and might even be dangerous to your health, and to the health of the building.

I am asking a very specific question about my vent and was not asking multiple obvious questions about general soundproofing.

The "very specific question" that you asked about your vent reveals that there is an underlying misunderstanding about how sound works, and about how isolation works. Once you have been around the forum for a while, you'll notice that acousticians and studio designers don't use the term "soundproofing" much, foe several reasons, but basically because it is meaningless (it means different things to different people), and also because it is impossible to actually "soundproof" anything! Any sufficiently loud sound will easily get past any conceivable barrier that man or nature can erect. The loudest sound ever recorded on planet earth was loud enough to crack thick concrete walls over 300 miles away: there is nothing man can do to "soundproof" a building against such a sound. What we CAN to, is to attenuate sound, by placing a barrier around it that reduces it's intensity to a level that is acceptable on the other side. This is referred to as "isolation", or "transmission loss". If you look at the books and research papers and graphs and things written by people who study sound, and who design sound isolation systems, you won't find them talking about how a wall "soundproofs" the building: you WILL find them talking about how it isolates the building, and how that can be measured in terms of "decibels of transmission loss".

That's what you need to do. Your very first order of business should NOT be to think about how to stop up the vent: Rather, it should be to figure out how much isolation you need! Plain and simple. If you do not know how much isolation you need, then you cannot possibly know how deal with your vent! Think about that.

That's what we are trying to tell you: You are asking the wrong question. You are asking a question that you think is valid, and correct, and important, but in reality it is meaningless because you have not yet defined your goal. You do not know if you need 30 dB of isolation, or 90 dB of isolation. Until you know that, your question simply does not have any valid answer! It's not that Greg is cryptically misleading you, or trying to be clever: not at all. He simply CANNOT answer your question, because NOBODY can answer it, since the question by itself makes no sense.

Think if it this way: if somebody comes up to you on the street, and says "To get where I'm going, should I turn left at the corner, or turn right?". Since you have no idea where he's going, and he didn't tell you, the question has no answer. NOBODY can answer his question! He would first have to tell you where he wants to go, and then you an help him. The same is true here: we can't answer your question because you have not told us the information we nee to answer it.

We are not avoiding your question: it's just that there is no valid answer to it, because it is not the right question!

The common theme of threads on this site seems to be asking for tons of info and then telling people that their idea will be ineffective -

Right! Because it usually is! That's why people come here: to learn. And they first thing that people usually learn, is that they did not understand the implications of what they were asking, because they do not understand sound. So we help them to understand sound, then the can understand WHY there proposed solution would not have worked, and finally move on to finding solutions that actually DO work.

It's like someone going to see the doctor, and telling him: "Doc, I have a cold, so I need antibiotics to fix that." Then when the doc says "No you don't: if you have a cold, then antibiotics wont help at all", the person says "But doc! That's not fair! I see that you area always telling people that their idea will be ineffective!". Maybe it's because the doc understands diseases and treatments, while the person who went to see him does NOT understand them, even though he thinks he does!

obviously the way sound works it's going to leak/flange through the weakest link

Probably, yes, but not necessarily. I'm sure you could turn that back on me and point to hundreds of threads where I have told people that isolation is only as good as the weakest link, and that0s quite correct. But that is NOT hte same as saying that sound is always going to leak/flange through the weakest link ... That sounds like a total contradiction in terms, but in reality it isn't. This is not meant to be another "cryptic" message to confuse you: it's simply stating fact. I could explain it for you, but I don't think that you would understand it yet, since you don't have the necessary knowledge of acoustics to follow the explanation, so all I can say here is "trust me, it's true". Once your level of understanding improves, then you'll get it yourself, without needing me to explain it.

but it would have been nice to just get a specific answer related to my specific vent question.

Yes it would, but there is no valid answer. Just like there is no valid answer that you could give to the guy on the street who wants you to tell him if he should turn left or right. He might get angry at you when you refuse to tell him, but you have no choice, because his question is not valid, as he gave you insufficient information to work with.

It would be actually possible to speak about my vent issue without addressing the doors, windows, room size, etc.

No, it would not. Until you define the level of isolation, it is NOT possible to speak about an valid answer to your question, regardless of any other info that you might or might not give us. If you don't tell us what the goal is for isolation, then there's nothing we can do to help you with your question.

So that's the issue here: we are not giving you the run.around to try to confuse you, or mock you, or anger you: We are not giving you the run-around at all! We are merely trying to help you understand that you are focusing on one tiny aspect of your studio isolation system, when it's clear that your focus is in the wrong place: that aspect IS important, yes, but you are asking the wring question about, and you still want to insist that we should answer your questions, even though we have repeatedly pointed out that you are looking at it in entirely the wrong way.

So, what I'd suggest is that you should FIRST do some tests to find out how much isolation you need, then re-phrase your question in valid terms, such as "How can I deal with this vent, considering that I know I cannot seal it up, but I also need 45 dB of isolation, and the rest of my studio will be built as a 2.leaf MSM isolation system that will provide 45 dB of isolation?". That would be a valid question, and one that we actually could answer.



- Stuart -