New multipurpose construction

[Eltrex]

Hello everybody. I have been searching the forum for answers to a new construction that I want to do and I was going to register to ask in some threads. I have seen that it is best to open my own thread because I have a lot of questions and a little help would be great. I have read the rules of the forum and I have been learning about study construction, but I still have many doubts to solve ...

My father has left me a space in his garage to record and mix mainly. Exactly it is not a garage, it is a great space for commercial use and it has let me make a room inside. Mainly the idea is to be able to record all types of instruments except acoustic drums. Guitars, synthesizers, bass, etc ... I'm not a professional, I do this mainly because I don't have a place to do it and I've been saving money a lot of time to get this construction done.

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I use the forum in English because I think it is much more active than my original language, Spanish. By the way, I'm from northern Spain.

My main goal is to create a room so as not to disturb the neighbors. That is my main concern. Most of the time we will be one or two people, never rehearsing a full band, and never with drums. Electronic drums only. There will be exceptional times that we meet more than two people, but most of the time we will be one or two.

My idea is to completely decouple the room for maximum insulation, but we started badly with the measurements. I know it's an almost perfect square, but I have to live with it. I'm not going to make a living with music, I just want a space where I can play and mix as well as possible.

At the moment I have two 1,41 in thick MDF walls with green glue between the panels supported on 2,75 x 2,75 in studs and I have bought 2,55 rock wool that will go between the studs. The other two walls are 3,14 thick hollow brick. I will do the construction with a highly experienced carpenter and it will start in a month. I hope to have some doubts resolved when it starts and that this post serves someone.


My budget is 10.000 to 11.000 USD máximum.

Here are some questions. In the answer to this thread

Here are some questions. I have a lot more, but in 1 month I´m going to read a lot in this forum

- In the answer to a thread that I cant find (sorry!!!) it is said that framing the brick wall is a waste of money, but my intention is to attach the rockwool to the wall and I thought that with some studs like in the MDF wall I could attach them to the wall. The brick is very thin, and my intention would be (from the outside to the inside) the brick wall, rockwool, air gap, rockwool and double MDF panel with green glue between panels. I thought the best way to attach rock wool to the walls was framing the wall ...

- I live in a mild climate, there is not much heat in summer nor much cold in winter, so I think it would only need ventilation and extraction. This is driving me completely crazy, and I will have a lot of questions about ventilation but the first is about baffle boxes. My question is if the duct goes inside the baffle boxes or when you reach the box you have to cut the tube so that the air runs free inside...

By the way, I forgot, the height of the floor to ceiling is 11.50 feet. Sorry I'm not more specific at the moment ... Thank you for reading this and greetings ...
I will continue reading this forum during this month before starting the work to learn more and I will be putting here any doubts I have ... Greetings!

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[Gregwor]

Welcome!

My question is if the duct goes inside the baffle boxes or when you reach the box you have to cut the tube so that the air runs free inside...

The boxes have what we refer to as "sleeves" that penetrate through any sheathing. There is no duct that goes in or through the boxes. If you need to connect any round, square or oval duct to the silencers to run through your MSM cavity or in your room, you can connect adaptors to the ends of the sleeves. See an example here:

Big Silencer Done.jpeg

So in that picture you can see the MDF sleeve that has the duct adaptor attached to it. The other duct adaptor is not connected to a sleeve because that duct will be inside of the MSM cavity and therefore not penetrating any sheathing.

Greg

[Eltrex]

Thank you very much for the answer, it has helped me understand some things. I think I now understand where the duct diameter is doubled so that the speed slows down. If I'm not mistaken, we must do it abruptly, and it seems that it is in one of the outputs of the baffle box. I'm sure this is going to help a lot of people. I have made a drawing about ventilation with an extractor, I don't know if it will be correct ...

baffle box ceiling.jpg

There are some questions

- Seeing your picture, I wonder if you attach the fan / extractor directly to the baffle box ... I don't know if my drawing will be correct.

- Somewhere I have read that the fresh air that enters the room must be at the top, on the ceiling, and that stale air must leave the room at the bottom, and quite apart. That the entrance and the exit are separated makes a lot of sense, but I don't know if it is true that fresh air must enter from above and stale air come out from below, near the ground. The large room to which my mixing room has a very good ventilation.

- In the photo you put you use a white paste and I don't know if it's caulk or noise soundproofing sealant.

- The duct that leaves the room in my drawing only comes out of one wall, but if I put it under the ceiling of the room and it has to cross the two leafs and the air gap it will join the two walls. What is the best way to try to soundproof that duct that crosses the walls of the room? As I read in this forum, I need to use lined flex duct, but at the moment that joins the two walls maybe I should give it a special treatment.

- The only space I have is almost a square, so my intention is to make the walls at irregular angles to minimize the impact of having an almost perfect square.

I have a lot more questions, and I will be here during the construction of the room posting photos and diagrams, maybe this can help more people like me.
Thank You Very Much!!!!

[Gregwor]

think I now understand where the duct diameter is doubled so that the speed slows down. If I'm not mistaken, we must do it abruptly

Correct. In "normal" HVAC, abrupt changes are forbidden. But, for us, the immediate impedance change is a major contributor to insertion loss.

and it seems that it is in one of the outputs of the baffle box.

Actually, the cross sectional area change is in the ENTIRE path within the silencer box itself. Just like how a muffler for your car is often 4 or more times bigger than the pipe entering and exiting it, our silencer box function is no different.

I have made a drawing about ventilation with an extractor, I don't know if it will be correct

- The extractor fan should be on the far side of the outer leaf silencer box. Fans are noisy and therefore you want any sound they create to have to pass through both the inner and outer leaf silencers.

- It isn't clear in your picture, but the inner leaf box should have a sleeve, that is made out of the same material as the box itself, penetrating the inner leaf sheathing. This will maintain the surface density of the leaf.

Otherwise it looks good!

- Seeing your picture, I wonder if you attach the fan / extractor directly to the baffle box ... I don't know if my drawing will be correct.

Again, the fan is usually placed after the outer leaf silencer boxes, not in between the inner and outer leaves.

- Somewhere I have read that the fresh air that enters the room must be at the top, on the ceiling, and that stale air must leave the room at the bottom, and quite apart. That the entrance and the exit are separated makes a lot of sense, but I don't know if it is true that fresh air must enter from above and stale air come out from below, near the ground. The large room to which my mixing room has a very good ventilation.

In an air tight room, the air is going to flow in and out of the only available areas. If you are using mini splits, it's advised to have the ventilation inlet above the mini split head so that the head blows fresh air around. Otherwise, I think the inlet and outlets can be anywhere vertically. They should just be as far away from each other as possible so that the air passes through the entire room.

- In the photo you put you use a white paste and I don't know if it's caulk or noise soundproofing sealant.

There are two different white products on that box. The MDF seams are sealed with regular caulk -- the stuff we use to seal everything in our air tight rooms. The metal duct connector was installed by putting a few beads of caulk on it's flange. Then the connector was brad nailed onto the MDF. After that, regular duct mastic was put onto the the duct connector flange.

- The duct that leaves the room in my drawing only comes out of one wall, but if I put it under the ceiling of the room and it has to cross the two leafs and the air gap it will join the two walls. What is the best way to try to soundproof that duct that crosses the walls of the room? As I read in this forum, I need to use lined flex duct, but at the moment that joins the two walls maybe I should give it a special treatment.

I covered this above. Each silencer should offer the same isolation (insertion lass) as the sheathing that it is penetrating. So, at the exit of the silencer within the MSM cavity, you can use whatever you want to connect to the other leaf's silencer box as long as it is flexible. Flex duct is easy to work with and that's why it's a good option. The biggest issue with flex duct is the amount of pressure drop it introduces when not completely stretched out straight.

- The only space I have is almost a square, so my intention is to make the walls at irregular angles to minimize the impact of having an almost perfect square.

You're going to need a place for your silencer boxes to live. You could frame out the room into more of a rectangle and then put the silencers into the cavity that you framed out. If I were you, I would either frame the room to be a rectangle like I just said, or else live with the larger square shape and put a LOT of treatment in there.

I have a lot more questions, and I will be here during the construction of the room posting photos and diagrams, maybe this can help more people like me.

Good stuff! Just make sure you 3D model everything before you build any more!

Greg

[Eltrex]

Correct. In "normal" HVAC, abrupt changes are forbidden. But, for us, the immediate impedance change is a major contributor to insertion loss.

If I'm not mistaken for what you say, suppose I have an extractor and a fan that need a 100 mm tube ...

From the outer to the inner sheet would be:

The extractor enters the outer baffle box with a diameter of 100 mm. At the exit of the outer baffle box, just when you are going to enter the first outer sheet, the diameter would be 200 mm and then it would be 200 mm to the inner grid inside the soundproof room ... It is an idea, please, correct me if I'm wrong.

I say all this because if the extractor is 100mm in diameter I need to enter the outer baffle box with a 100mm adapter

It isn't clear in your picture, but the inner leaf box should have a sleeve, that is made out of the same material as the box itself, penetrating the inner leaf sheathing. This will maintain the surface density of the leaf.

Of course, I will use the same material, double layer MDF with green glue.

In an air tight room, the air is going to flow in and out of the only available areas. If you are using mini splits, it's advised to have the ventilation inlet above the mini split head so that the head blows fresh air around. Otherwise, I think the inlet and outlets can be anywhere vertically. They should just be as far away from each other as possible so that the air passes through the entire room.

I am only going to use a fan and an extractor, because here the weather is very mild, and neither in winter it is very cold nor in summer it is very hot. The room to which both the fan and the extractor will be connected is extremely well ventilated.

There are two different white products on that box. The MDF seams are sealed with regular caulk -- the stuff we use to seal everything in our air tight rooms. The metal duct connector was installed by putting a few beads of caulk on it's flange. Then the connector was brad nailed onto the MDF. After that, regular duct mastic was put onto the the duct connector flange.

All clear!!. Thank You!!!

I need to live in the shape of a square, because I need all the available space in the room. I have tons of gear and I have to make the most of it. I am completely sure that to fix the acoustics of the room I will need to use resources, but the main thing for me is to use reference songs, try to fix as much as possible the acoustic problems that may arise and I know that it is not the ideal way to do it, but as long as it doesn't bother the neighbors and have a space where I can make some noise, I will be happy.

[Eltrex]

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These two brick walls have many holes, so I have decided that I will put a layer of cement on the two walls to cover everything. I think it's the best way to avoid leaking holes and sound leaks. I tried to cover the holes but I don't think it's the best solution.

The roof is the same, but since I can't cover it with cement I was thinking of covering it with MLV ... 16 m2 would be about 100 dollars

[Gregwor]

The extractor enters the outer baffle box with a diameter of 100 mm. At the exit of the outer baffle box, just when you are going to enter the first outer sheet, the diameter would be 200 mm and then it would be 200 mm to the inner grid inside the soundproof room ... It is an idea, please, correct me if I'm wrong.

If your fan is 100mm, then as soon as the duct work hits the outer leaf silencer box, it must at LEAST double, so the inner cross sectional area of the box should be 200+mm. Exiting the outer leaf silencer box, the hole should be 100mm again. Then, the inner leaf silencer box will also be double the CSA inside (200+mm) and the hole in the silencer box that is the "register" so to speak, inside the room, needs to be the correct CSA in order to provide you with an air velocity less than 300 feet per minute.

I am only going to use a fan and an extractor,

Please educate me here. I thought an "extractor" used in our thread here was in fact the fan itself.

Greg

[Eltrex]

If your fan is 100mm, then as soon as the duct work hits the outer leaf silencer box, it must at LEAST double, so the inner cross sectional area of the box should be 200+mm. Exiting the outer leaf silencer box, the hole should be 100mm again. Then, the inner leaf silencer box will also be double the CSA inside (200+mm) and the hole in the silencer box that is the "register" so to speak, inside the room, needs to be the correct CSA in order to provide you with an air velocity less than 300 feet per minute.

Thank you. I have been quite clear except the end of the circuit, I do not know if inside the room, where you have to put the grid are 100 or 200 mm.
I have made a drawing to see if it is correct and I have understood it well. I am trying to draw with 3d programs but as I have never done it, I am very slow. Sorry for the 2D drawing.

Baffle boxes.jpg

I will try to explain the question of the fan and the extractor, because it is what I have less knowledge about. I was looking for a solution both to inject air into the room and to extract it, and I called a well-known company that manufactures quality fans and fans here in Spain. I was told that the best solution was to buy two extractors / fans.
They explained to me, and it is very logical, that I can buy the product and use it in two different ways, both to blow air into the room and to extract it, I just had to change the direction of the air. In my opinion, if you inject air into a room, it works like a fan, and if you take it out, it works like an extractor. Being two fans / extractors equal and have the same speed and the same capacity (although you can vary the speed) there may be a more homogeneous air passage ... I do not know ...

These are the specifications of the fan/extractor, I don´t know if I can put here links to products.

In-line low-profile, extremely quiet, certified silencer fans by the Noise Abatement Society, made of plastic material, with acoustic elements (perforated internal structure that directs the sound waves, and internal sound-absorbing insulation that dampens the radiated noise) (1), removable body-motor without touching the ducts, rubber seals on discharge and discharge to absorb vibrations, 360º adjustable external terminal box, IP44 , 230V-50Hz motor, 2 or 3 speeds, depending on the model, adjustable by voltage variation, Class B, permanent lubrication ball bearings, condenser (2) and thermal protector.

Velocity (RPM) 2210-1680
Maximum absorbed power (W) 27-21
Maximum absorbed intensity (A) 0.12-0.1
Free discharge flow (m3/h) 250/200
Sound pressure level (dB(A)) 25/20

These are the ones I have found, they are of good quality and they are also a bit expensive, but they may be the best I can get in my utmost ignorance about the topic of ventilation. If someone can recommend me some other product I would be happy to take a look and weigh other options.

[Eltrex]

I also wanted to ask about the floor, since the interior of the room has been leveled with a 4cm layer of concrete, and I have seen a video where on that concrete layer they put some rubber cubes and they fill everything with rockwool to then put on top double panel of MDF 19mm with green glue. The original floor is made of concrete (I don't know how thick it will be, but I measure a couple of cm at most, and under the concrete there are large blocks of bricks and concrete slab beams. Under all this there is a garage. I don't know if it will be the correct way to raise the floor .... Or simply with the concrete layer that I have put to level and the original floor will be enough...

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[Gregwor]

I have made a drawing to see if it is correct and I have understood it well.

Your drawing doesn't show your silencer box sleeves penetrating your sheathing. Otherwise it looks good. Your opening of your inner leaf box inside your room is labeled as "100mm??". This cross sectional area can easily be calculated by knowing the CFM passing through your boxes and knowing that you need to have a maximum of 300 feet per min air velocity.

I will try to explain the question of the fan and the extractor, because it is what I have less knowledge about. I was looking for a solution both to inject air into the room and to extract it, and I called a well-known company that manufactures quality fans and fans here in Spain. I was told that the best solution was to buy two extractors / fans.
They explained to me, and it is very logical, that I can buy the product and use it in two different ways, both to blow air into the room and to extract it, I just had to change the direction of the air. In my opinion, if you inject air into a room, it works like a fan, and if you take it out, it works like an extractor. Being two fans / extractors equal and have the same speed and the same capacity (although you can vary the speed) there may be a more homogeneous air passage ... I do not know ...

You need 1 fan on the exterior of your outer leaf silencer box (supply or return, it doesn't really matter). Since your room will be air tight, if a fan is pushing air in through the supply, the air will automatically be pushed out of the room through the return as well. And if a fan is sucking air out of the room through the return, automatically, it will suck air in through the supply.

These are the ones I have found, they are of good quality and they are also a bit expensive, but they may be the best I can get in my utmost ignorance about the topic of ventilation. If someone can recommend me some other product I would be happy to take a look and weigh other options.

Your fan needs to be variable speed so that you can dial in the correct CFM. However, more importantly, you need to make sure that your fan is able to move your required CFM under the static pressure of your system. Once you estimate your in. w.g. and know your required CFM, then you can quite easily find an inline duct fan that would work for you.

I don't know if it will be the correct way to raise the floor .... Or simply with the concrete layer that I have put to level and the original floor will be enough...

If you're on the second floor, it might be a good idea to partially decouple your floor by setting it on insulation like you've suggested.

Greg

[Eltrex]

Hello again. Every time you answer me in this post I feel a wave of infinite terror inside me, I feel like a damn ignorant ...

Your drawing doesn't show your silencer box sleeves penetrating your sheathing. Otherwise it looks good. Your opening of your inner leaf box inside your room is labeled as "100mm??". This cross sectional area can easily be calculated by knowing the CFM passing through your boxes and knowing that you need to have a maximum of 300 feet per min air velocity.

When you say that the boxes should penetrate the sheets, I don't know if I understand correctly. Does it mean that I need to embed the box inside the sheets by cutting a rectangle in them? Wouldn't it be worth simply sticking them to the double wall with screws or whatever, and inserting a tube between them in the air chamber? It is something that I do not understand very well, as far as they have to penetrate, if they have to be together inside the air chamber or if I must join them with line flex duct ...

I have been looking at the specifications of the fan and it gives a flow of 250m3 / hour maximum and 200m3 / h minimum. Converting it to CFM would be 147.1CFM maximum and 117.7 CFM minimum. I don't know if it will be enough inlet air ...

You need 1 fan on the exterior of your outer leaf silencer box (supply or return, it doesn't really matter). Since your room will be air tight, if a fan is pushing air in through the supply, the air will automatically be pushed out of the room through the return as well. And if a fan is sucking air out of the room through the return, automatically, it will suck air in through the supply.

Oooo OK!!! Only one fan, it has a lot of logic, the stale air will be free by the exit ... And I was going to buy two !!!!

Your fan needs to be variable speed so that you can dial in the correct CFM. However, more importantly, you need to make sure that your fan is able to move your required CFM under the static pressure of your system. Once you estimate your in. w.g. and know your required CFM, then you can quite easily find an inline duct fan that would work for you.

I'm sorry, but I don't understand what "in. W.g." means. in your sentence ...

Well, I keep learning a lot and I hope to be here all the time, when I have more knowledge maybe I can help someone else ... Thanks to a single fan I will save money When I finish my construction I will make a donation to the forum for the invaluable help ... I give you my word. Thank you!!!!!

[Gregwor]

Hello again. Every time you answer me in this post I feel a wave of infinite terror inside me, I feel like a damn ignorant ...

I'm sorry for making you feel that way. I try to get to the point in my responses and I apologize if it comes across as being mean. You're doing great and please be excited to read responses instead of feeling terror

When you say that the boxes should penetrate the sheets, I don't know if I understand correctly. Does it mean that I need to embed the box inside the sheets by cutting a rectangle in them? Wouldn't it be worth simply sticking them to the double wall with screws or whatever, and inserting a tube between them in the air chamber? It is something that I do not understand very well, as far as they have to penetrate, if they have to be together inside the air chamber or if I must join them with line flex duct ...

Here is a Y split style silencer in which the air path splits in two. Each half of this one will have an air path at least twice the cross sectional area as the round duct feeding it. Therefore, this box achieves great insertion loss by at least quadrupling the cross sectional area! Pretty awesome. Most of us don't have the space for such large silencer boxes like Frank did with his build here! So, in this picture, you can see the drywall on the ceiling. That is actually his outer leaf sheathing. This silencer box is his inner leaf silencer box. I've circled the sleeves that I'm talking about.

Sleeves.jpg

I believe this may be the same silencer box in the following picture. You can see that Frank then framed up his inner room. The boxes are now above his inner leaf ceiling joists.

Inner leaf boxes over ceiling joists.jpg

He will then slide what is often referred to as "ceiling modules" up into the joists to create and inside out ceiling. The modules are often sheathed with a combination of OSB and drywall. This sheathing would have holes cut in it that would allow the sleeves to penetrate it like this (you can see a sleeve sticking through near the bottom left of the picture):

BRAUS-iso-ceiling-in-other-end-SML-ENH.jpg

This sleeve will ensure that the surface density is always maintained in the room.

I have been looking at the specifications of the fan and it gives a flow of 250m3 / hour maximum and 200m3 / h minimum. Converting it to CFM would be 147.1CFM maximum and 117.7 CFM minimum. I don't know if it will be enough inlet air ...

The issue with our silencer boxes is that they basically break all the rules of standard HVAC design. Unfortunately, it's the only real effective cheap way to achieve the insertion loss we need. Having said that, the silencer boxes introduce a lot of static pressure to the system. Calculating the static pressure is a bit of a nightmare. I've put together a calculator to get a rough idea of the static pressure of your system but it isn't very user friendly, yet. The CFM figures you posted about the fan are drastically affected by different amounts of static pressure. So, you need to make sure your fan can provide the CFM you need at the static pressure your system will impose on it. Most fans I've looked into have a chart that shows the fans maximum CFM output operating under different amounts of static pressure like this one:

Performance Curve.png

Oooo OK!!! Only one fan, it has a lot of logic, the stale air will be free by the exit ... And I was going to buy two !!!!

I'm sorry, but I don't understand what "in. W.g." means. in your sentence ...

That is a unit of measure for static pressure. It stands for Inches of Water Gauge.

You can find my calculator here for now (again, I hope to make a user friendly version sooner than later):

http://www.johnlsayers.com/phpBB2/viewt ... 52#p149148

Well, I keep learning a lot and I hope to be here all the time, when I have more knowledge maybe I can help someone else

That's the idea! The more people that contribute, the better. Less workload for myself and the others that try to help out!

When I finish my construction I will make a donation to the forum for the invaluable help ... I give you my word. Thank you!!!!!

That's very kind of you. It's amazing to think how generous John is for paying the monthly bills to keep this site up and running!

Greg

[Eltrex]

I'm sorry for making you feel that way. I try to get to the point in my responses and I apologize if it comes across as being mean. You're doing great and please be excited to read responses instead of feeling terror

You don't have to apologize for anything. I thank you for the invaluable help !!!

Here is a Y split style silencer in which the air path splits in two. Each half of this one will have an air path at least twice the cross sectional area as the round duct feeding it. Therefore, this box achieves great insertion loss by at least quadrupling the cross sectional area! Pretty awesome. Most of us don't have the space for such large silencer boxes like Frank did with his build here! So, in this picture, you can see the drywall on the ceiling. That is actually his outer leaf sheathing. This silencer box is his inner leaf silencer box. I've circled the sleeves that I'm talking about.

Looking at the photos and reading your answers, I think I am getting a much better understanding of the mysterious world of baffle boxes. I would just know the dimensions and I hope to do it this week
I think that with a simple rule of three I can know how much the dimensions of the inner hole, that of the ceiling, through which the air is going to enter into the room. If for a 100mm duct the speed is 147.1 CFM, for 100 CFM the entrance hole would be 67.98 mm...

I am planning to use the minimum possible duct to not force the fan, my plan is to put it right in a corner of the room on the outer leaf, and just in front of the interior, place the inner baffle box.

I found the performance graphic of the fan, this is it.

td250.jpg

I've been looking at your calculator this morning, it's great, I have to look at it more carefully because the calculator is far beyond my knowledge

Once again, I apologize for putting a 2D side view drawing, but I think that is much better understood.

Union.jpg

This is a question I have been asking for several days and it is important ...
At the junction of the walls with the floor should I leave a small gap to insert backer rod and then fill with caulk? Can't you touch walls and ceiling only with backer rod? Which is better, support the walls on the floor or lower the walls a little more from the ground and bring the floor to the walls? I do not know if I explained well...

Thanks!!!!!!!!!!!!

[Gregwor]

I don't fully understand your drawing but what matter right now is answering your question:

At the junction of the walls with the floor should I leave a small gap to insert backer rod and then fill with caulk? Can't you touch walls and ceiling only with backer rod? Which is better, support the walls on the floor or lower the walls a little more from the ground and bring the floor to the walls? I do not know if I explained well...

Yes, you should leave a small gap. Backer rod will help if your gap is large as it will limit the depth of the gap, ultimately saving you a lot of money on wasted caulk. Your caulk should be at least half the depth of your drywall in order to maintain the surface density. This is because caulk typically has about twice the surface density that drywall has.

Greg