How to ventilate an underground garage/basement studio

[Soundman2020]

Steel framing is not rigid like wood. You start by fastening the frames then add the drywall.

Are you SURE about that?

metal-framed-shed-leaf-structure-self-supporting-1-SML.jpg

Like I said: Use STRUCTURAL metal framing, not light-weight metal framing, which is flimsy and not meant for carrying heavy loads.

I just don't see how this is possible structurally

Then you are not looking in the right places!

metal-framed-shed-leaf-structure-self-supporting-6.jpg

This is a VERY common way of building houses and all kinds of other buildings these days.

Steel-Framed-Houses.jpg

lgsf-site-500x500.jpg

steel-framing-house.jpg

It's the same basic concept as light-framing, except the metal is thicker, and the parts are specifically designed for structural assemblies.

perhaps for this reason those of us without access to wood have developed a different way of doing things than you guys

I'm not sure why you would think that. Both wood framing and metal framing are very common, all over the world. Just because your local hardware store does not stock wood, that doesn't mean you can't get it. And just because they don't stock structural steel framing, that also doesn't mean you can't get it. It just means you need to go to a different place that DOES stock it.

Living where you do, I'm surprised that you didn't know that steel can be used as structural members for large construction projects:

58d919eaf2d0331b008b4bbd-750-562.jpg

- Stuart -

[buttermuffin]

hahaha, the Eiffel tour!, well I think you are obviously not suggesting that I use a similar steel to build my studio as is used in the Eiffel tower . Stuart, I am only speaking about practical and economically viable solutions. These options are not suitable because:

1) I am almost certain (but will double check this) that this material is much more difficult to find because I have not seen it on sale anywhere, the light gauge steel framing is the staple here and masonry for outer leaf construction.
2) much more expensive, in which case wood would start to seem more appealing
3) Most importantly: How would I build this? Where is the info on a studio that has been built this way so I can learn how to do this? Where are the resources. If they don't exist here (and if they did you would have sent something by now) then they don't exist!
4) More difficult from a DIY perspective? I think it must be.

Nah, I think I am just going to go with my original plan and when I am done I will do a test too so it will be nice to compare the two systems. Like I said I am not going to be sad about not getting 50 db of isolation.



I would like to add that in Rod Gervais' book he says that not only can light gauge steel framing be used but that it has advantages over wood in that it offers superior isolation. It is a pity he does not say how the room in a room is assembled with light gauge steel framing. Perhaps that could make a great useful addition to this forum *hint hint*.

[buttermuffin]

The way I saw it when planning this is that having the 2 leaf system AND then having another leaf can only improve isolation.

No it cannot. IT can only make it WORSE for low frequencies. It might be better for mids and highs, but they don't matter so much anyway, but it WILL be worse for lows, all other factors being equal.

Even if the 3rd leaf is 1 meter away? I have read that this is true for when the 3rd leaf is close the other 2 leaves

[buttermuffin]

Going back onto the topic of ventilation, I have 2 more questions please. I was browsing a duct supply store and found this image

If you use a splitter like this in your duct-work to split the duct into two then are you effectively doubling the cross sectional area? I ask because it would be nice to have 2 supply and 2 return vents in the room at different locations and if this also gets me less FPM at my registers then all the better

Also, how exactly do you make the connection between a sleeve and a round duct? The sleeve will be rectangular as it penetrates the leaf but if I need to attach a round duct onto the that, do I need some kind of connector?

Thanks!

[buttermuffin]

Will you guys still help me please?

[Gregwor]

Even if the 3rd leaf is 1 meter away?

I don't have it on this computer, but there is a 3 leaf MSMSM calculation you can do to check that. In your case, and the fact that you don't need extreme isolation, don't worry about that 3rd leaf a meter away.

If you use a splitter like this in your duct-work to split the duct into two then are you effectively doubling the cross sectional area?

Yes.

I ask because it would be nice to have 2 supply and 2 return vents in the room at different locations and if this also gets me less FPM at my registers then all the better

Correct.

Also, how exactly do you make the connection between a sleeve and a round duct?

Any way you can think of. There are smooth transition adaptors and their benefit is reduced turbulence, however, they don't offer the drastic impedance change of an immediate size change. You could have a larger rectangular sleeve, put a cap over the end and then cut out a round hole in which you put your round duct. Like I said, anything you can think up will probably work.

Will you guys still help me please?

Sorry about the wait. It's hard to find time to answer everyone every day. My personal designs and other work takes a hit every day I'm on here for an hour or 2. The beauty of it though is that helping people solve their problems makes me think and research and learn. Plus, the only other person that seems to answer questions around here is the elder wizard Stuart Allsop. I'm trying to take some weight off his shoulders even though I'm a noob. I'm learning though and am eager to always learn more.

Greg

[buttermuffin]

I ask because it would be nice to have 2 supply and 2 return vents in the room at different locations and if this also gets me less FPM at my registers then all the better

Correct.

Fantastic! Having the airflow split like this within the room and having two vents is much easier than making the cross-sectional change in the silencer as it is a very heavy and big unit. If I change my cross-sectional area inside the silencer from 6" to 8" then I can further reduce the flow rate by using this splitter to get to 300FPM.

Will you guys still help me please?

Sorry about the wait. It's hard to find time to answer everyone every day. My personal designs and other work takes a hit every day I'm on here for an hour or 2. The beauty of it though is that helping people solve their problems makes me think and research and learn. Plus, the only other person that seems to answer questions around here is the elder wizard Stuart Allsop. I'm trying to take some weight off his shoulders even though I'm a noob. I'm learning though and am eager to always learn more.

Greg

Thanks Greg. I totally understand

[Soundman2020]

Having the airflow split like this within the room

... means that you have high velocity air inside a duct with a very thin wall, through which sound can escape into the room. You will need to isolate your ducts, to keep that sound out of the room.

and having two vents is much easier than making the cross-sectional change in the silencer as it is a very heavy and big unit.

However, you will still need a long straight run after the split, to allow the turbulent flow to settle down and become more laminar, before it reaches the register. Implying that you will need TWO long runs, once for each branch of the duct. I'm not so sure you'd be saving much space.

It's hard to find time to answer everyone every day.

- Stuart -

[buttermuffin]

Having the airflow split like this within the room

... means that you have high velocity air inside a duct with a very thin wall, through which sound can escape into the room. You will need to isolate your ducts, to keep that sound out of the room.

Oh ok thanks Stuart. I never thought that this would be an issue so I will keep thinking about this one. Maybe I can do tests after the room is built and silencers in place. According to my calculations, once the sound hits the inside of the room it will be flowing at around 500FPM. What if I use a thicker duct for that run? Do you think that might keep the sound contained within the duct work? Also I am not sure what effect the the absorber will have on that sound passing through the ductwork. I plan to have the duct running within the ceiling treatment which will be a 50cm thick absorber. Maybe it can help reduce the sound of the air.

and having two vents is much easier than making the cross-sectional change in the silencer as it is a very heavy and big unit.

However, you will still need a long straight run after the split, to allow the turbulent flow to settle down and become more laminar, before it reaches the register. Implying that you will need TWO long runs, once for each branch of the duct. I'm not so sure you'd be saving much space.

[/quote]

Ok gotcha! How long do you think after the split? Will 1 or 2m be ok?

Also, is it better to have an equal number of exhaust and intake registers or is it ok to have two of one and one of another? So like 2 exhaust registers and one supply register in the room?

[buttermuffin]

I am just about to start creating my silencers but I still have not decided on the type of ducts I will use and I am also struggling to find duct liner for some reason

As far as duct is concerned I wanted to as you if you think that this will this work for creating ducts? It has aluminium on the outside and some other black material on the inside although I am not sure what it is. I am guessing this makes using ductliner void. Has anyone here worked with such materials and is it recomended?

[Soundman2020]

I have not worked with that personally, but yes it is a valid way of making ducts, and yes that is duct liner on the inside. That product is often called "duct board" or "duct panel", and you can shape it yourself. You could use that if you wanted to.


- Stuart -

[buttermuffin]

I have not worked with that personally, but yes it is a valid way of making ducts, and yes that is duct liner on the inside. That product is often called "duct board" or "duct panel", and you can shape it yourself. You could use that if you wanted to.


- Stuart -

Thanks!

[buttermuffin]

Dear Stuart & Greg

When having a duct running straight horizontally is it possible to place a register below it at the end without bending the duct like the lower option in this diagram? I was hoping to be able to do something like this but not sure if this is acceptable/possible or not.

Thanks!

[Waka]

Dear Stuart & Greg

When having a duct running straight horizontally is it possible to place a register below it at the end without bending the duct like the lower option in this diagram? I was hoping to be able to do something like this but not sure if this is acceptable/possible or not.

Thanks!

Hi buttermuffin, I know you directed your question towards the other guys, but as you haven't had a response yet I thought I'd offer a response.

The curved bend before the register will reduce turbulence in the air flow and reduce buffeting, this is desirable, on the other hand I have seen many designers using the second design and it turning out fine. Provided you have a low enough air velocity I can't imagine you having many problems with the second design.

[buttermuffin]

Dear Stuart & Greg

When having a duct running straight horizontally is it possible to place a register below it at the end without bending the duct like the lower option in this diagram? I was hoping to be able to do something like this but not sure if this is acceptable/possible or not.

Thanks!

Hi buttermuffin, I know you directed your question towards the other guys, but as you haven't had a response yet I thought I'd offer a response.

The curved bend before the register will reduce turbulence in the air flow and reduce buffeting, this is desirable, on the other hand I have seen many designers using the second design and it turning out fine. Provided you have a low enough air velocity I can't imagine you having many problems with the second design.

Thanks Waka. I like the second design because it will require much less vertical space and think I will go with it. My only doubt now which I am researching is figuring out how to make the connection to the register at the end of the duct. I will be using duct board so I am guessing the best way is to cut a hole and simply stick the register in it. I like to be sure about all my steps in advance so am still researching this. If you know anything about this please let me know

Im following your threads with great interest, keep up the good work

thanks again