Bellyacres - Basement Studio Design

[DanCostello]

Hey guys,

My goal is to convert the front half of my basement into a 5.1 control room + vocal booth. The CR would double as a live room somewhat larger than the booth - I do sound design and most of my recording is more like what you'd think of as foley, and I'd be recording myself most of the time. So, I need decent isolation, but not a bunch of rooms or space for a whole band. The most crowded it will usually be is if the wife joins me down there to watch a movie.

I plan on leaving the rear ~half of the basement for washer/dryer/furnace/etc and a treadmill and tv for The Mrs.

The house is a brick rowhouse. I believe the foundation walls are some combination of brick and field stone, but it's hard to tell because it's all covered with a thick, uneven layer of mortar. If the rear wall is indicative of the rest, then the brick extends about 2' below grade and the ?stone? makes up the bottom 4' of the walls. The front booth area is beneath the front porch, while the rest of the studio area is below my living room. The floor of the entire basement is a concrete slab.

While I won't be terribly loud and the neighborhood isn't terribly loud aside from some traffic, impact noise from the neighbors is a real issue. It's easy to hear the toddler next door running around.

This is the first draft of my design:

Basement_Draft01_top_NoJoists_NoRays_NoUtilities.PNG

The plan is to have 3x Adam A77X up front, 2x A7X for surrounds, and a to-be-determined Adam sub. The LCR speakers will be soffit-mounted, while the surrounds will (probably) be on stands. The dark grey panels outside (offstage?) of the wooden soffits and in the rear corners represent bass traps. Sizes and placement of the bass traps are rough guesstimates, and I haven't planned any of the interior treatments yet.

The interior floor space of the CR is about 221 sq ft (volume is ~1,769 cu ft). Floor space of the booth is about 61 sq ft and the volume about 435 cu ft. I realize that the room is almost square and the dimensions don't fall in line with the preferred ratios of studio dimensions, but this is all the space I have. As you can (hopefully) see from this picture:

Basement_Draft01_top_Joists_Utilities_NoRays.PNG

...I'm boxed in by the stairs, pillars (light grey squares in the pictures), sump (the blue circle at the top center), and the existing plumbing (green cylinders) and other utilities(bottom center-right). And with hot water radiators and a natural gas supply on the opposite side of the basement from the furnace and water heater, a bathroom and kitchen on the opposite side of the house from the sewer outlet, and a sewer outlet that's not completely buried in the slab, there's a lot of plumbing, most of which sits below the level of the ceiling joists.

Here are a couple perspective shots with and without the projection screen.

Basement_Draft01_rear_perspective.jpg

Basement_Draft01_rear_perspective_NoScreen.jpg

And one from above with the rays traced out from the speakers:

Basement_Draft01_top_Rays.PNG

So, given my space restrictions and goals, how does the rough draft look? Am I on the right track or is this really problematic. I do have a couple questions/concerns myself that I'll put in the next post.

[DanCostello]

The couple of immediate questions I have involve the assymetrical soffits, the ceiling, and the rear wall.

1.) Regarding the soffits (the ones on the ceiling covering the plumbing, not the ones in which the speakers are mounted):

Basement_Draft01_rear_Couch_Ceiling_Soffits.jpg

You can see that I have a soffit running along the top of the left wall, but not one along the top of the right wall. It may very well be the case that once I figure out the HVAC, I'll have to install a matching soffit on the right wall. But as of now, I don't have one there. Is this asymmetry a problem? If so, how big of a problem is it?

2.) Regarding the ceiling, the current height of the joists off the floor varies between about 8'1" and 8'3". It's safe to assume that once the floor is leveled, they will be no higher than 8'. I'm 6'5", so ceiling height is pretty important, and with only about a foot and a half between my head and the joists, I need all I can get. In order to maximize headroom, I was planning to suspend the ceiling drywall from resilient channel (or something like it) rather than put up new joists on top of the new walls. While I could interleave the two sets of joists to save space, the existing joists have crossbracing between them:

Basement_Draft01_crossbracing.PNG

Interleaving new joists with the existing joists while still clearing the crossbraces means that the new joists would have to sit at least 4" lower than the existing ones (assuming I use 2x8's identical to what's already there). Resilient channel, OTOH, is only about 1/2" thick. That 3.5"+ of headroom is a big deal. Are there any issues I should know about before using resilient channel on ceiling joists? I don't know how to accurately estimate the static load on these joists, but I can't imagine it's more than the 10 lb/sq ft target everybody uses. Above the joists are a hardwood floor and a mostly-empty living room. Suspended from them will be a couple layers of drywall, and probably some acoustic panels and small lighting fixtures.

3.) Regarding the rear wall of the control room - this is probably my biggest concern. It's flat, it's perpendicular to the direction I'd be sitting, it's the only place I can put the egress door, and I'm not sure how to build it as a 2-leaf system, or if I should at all. NBD, right?

3a.) Regarding it's being flat and perpendicular to me, one thought I had to correct this was to make the inner face of the wall into two angled faces like this:

Basement_Draft01_top_RearWallAngled.PNG

I've seen similar profiles in other plans here, though AFAIK, it's typically the case that the wall is built flat and then the angled profile on top of it is achieved through some sort of acoustic treatment. Would there be an issue with making a triangular wall like this? Is it worth the bother?

3b.) Regarding the building of this wall as a 2-leaf system: my thinking was that the rest of the walls in the model would be built as single leafs, so that either the basement foundation or the wall of the adjacent studio room would function as the 2nd leaf of the MSM system. (e.g. CR leaf + Booth leaf = 2 leaves. CR leaf + foundation = 2 leave) But the rear studio wall is so far from the rear foundation wall, that it's my understanding that this wouldn't really function as a 2-leaf system. And in any case, as you can see from this picture:

Basement_Draft01_rear_perspective_BackHalf_Utilities.jpg

the furnace, washer/dryer, and plumbing would all be between the leaves - and while they're not typically too loud, I'd like to block out those sounds, too, if possible.

Would it be best to build this rear wall as a 2-leaf wall? If so, would doing that require extending the outer leaf (i.e. the side facing the washer/dryer) all the way to the foundation walls? Would there be issues with the outer leaf having some small-ish openings to accommodate things like drainage and plumbing? Or does the outer leaf have to be hermetically sealed, too?

[DanCostello]

I went and re-read through some of Rod Gervais' book and answered some of my own questions.

1.) Yes, the soffits need to be symmetrical.

2.) Definitely going to have to go with a resilient channel system. I'd forgotten about R$IC clips, which are an intere$ting option to increa$e the i$olation. PAC Intl has a low-profile model that claims to allow you to get the gap between framing and drywall as small as 1/2". But, yeah, wow.... The cheapest ones I've seen are $4.70/each.

I'm still not sure if I should be concerned about the load capacity of my joists. They're 2x8's and while I don't have the exact measurements in front of me at the moment, the pics make it look like the span is about 13', which is about 12-24" longer than the recommended span for 2x8's (depending on the kind of wood, which I don't know). I could see myself easily going over 10 lb/sq ft with a couple layers of drywall mounted between the joists and then another couple hanging from them. But then, the dynamic load on those joists is typically very light. Is it ok to go over on one if you're typically way under on the other?

3.) The Mrs says she doesn't care about having a tv in front of the treadmill (or that I could hang one from the ceiling if I wanted), so sliding doors are on the table for rear wall.

[Soundman2020]

Is this asymmetry a problem? If so, how big of a problem is it?

Depending in how far down into the room that soffit will come, and how large it is, it might or might not be a problem, acoustically. However, it might also be an issue visually...

I need all I can get. In order to maximize headroom, I was planning to suspend the ceiling drywall from resilient channel (or something like it) rather than put up new joists on top of the new walls

Assuming that you are not aiming for very high levels of isolation, that probably is your best option. I would go for two layers of 5/8" drywall with Green Glue in between, hung from RSIC clips with hat channel. Another option might be one layer of 3/4" OSB or MDF on the RSIC+Hat Channel, then a layer of 5/8" drywall, also with Green Glue. More mass, more thickness, = higher isolation, but also the advantage of having a nailing surface across the entire ceiling. Either way, cut the drywall (and MDF/OSB) a but smaller than it needs to be, so that it does not touch the walls, leaving a gap of a few mm all around. Then put in backer rod and caulk.

I don't know how to accurately estimate the static load on these joists,

Then call in a structural engineer! He's the only person qualified to tell you what the load is right nowm and how much extra load you can hang from there, safely.

but I can't imagine it's ...

Don't imagine. Don't assume. Don't guess. Get an expert to go take a look and give you his professional, qualified opinion. When it comes to structural issues, don't play around. Bite the bullet, pay the fee, and get qualified, certified, professional expert advice.

3.) Regarding the rear wall of the control room - this is probably my biggest concern. It's flat, it's perpendicular to the direction I'd be sitting, it's the only place I can put the egress door, and I'm not sure how to build it as a 2-leaf system, or if I should at all. NBD, right?

From your diagram, it seems like you are still missing the point: The entire room is a two-leaf system. You build it as "one room inside another room". At present, you are not showing that. You have an outer-leaf wall on the right hand side of the room that you can use, but you also need the walls on the other three sides to complete the outer-leaf shell.... Then you build the actual inner-leaf control-room within that shell.

3a.) Regarding it's being flat and perpendicular to me, one thought I had to correct this was to make the inner face of the wall into two angled faces like this:

You could do that if you wanted to. Or you could add treatment to the entire rear wall (including the back of the door) that accomplishes the same thing.

3b.) Regarding the building of this wall as a 2-leaf system: my thinking was that the rest of the walls in the model would be built as single leafs, so that either the basement foundation or the wall of the adjacent studio room would function as the 2nd leaf of the MSM system. (e.g. CR leaf + Booth leaf = 2 leaves. CR leaf + foundation = 2 leave) But the rear studio wall is so far from the rear foundation wall, that it's my understanding that this wouldn't really function as a 2-leaf system. And in any case, as you can see from this picture

As I mentioned above, you MUST complete the outer-leaf shell, then build the room within that. Here's a diagram of how it should look, generically. In this case I did it for a set of three individually isolated rooms next to a non-isolated room, to show how each one is done as a separate leaf, yet each one also works as a two-leaf system with respect to all of the adjacent rooms:

MSM-two-leaf-WallChunk-conventional-.png

Would it be best to build this rear wall as a 2-leaf wall?

See above: The entire room is built as a two-leaf system, not just one of the walls.

If so, would doing that require extending the outer leaf (i.e. the side facing the washer/dryer) all the way to the foundation walls?

Yes.

Would there be issues with the outer leaf having some small-ish openings to accommodate things like drainage and plumbing? Or does the outer leaf have to be hermetically sealed, too?

Yes. And Yes. The outer leaf is a sealed shell. The inner leaf is a sealed shell. If there is any gap, hole, or crack in either of those, then the isolation is trashed. If air can get through, then so can sound.

I'm still not sure if I should be concerned about the load capacity of my joists.

Yes you should be! Hanging heavy stuff above your head is dangerous. You MUST get a professional opinion on this.

longer than the recommended span for 2x8's (depending on the kind of wood, which I don't know).

... and also depending on the live load, the dead load, the design deflection, and several other factors. Don't guess. Get a structural engineer in.

- Stuart -

[DanCostello]

Quote:
Is this asymmetry a problem? If so, how big of a problem is it?

Depending in how far down into the room that soffit will come, and how large it is, it might or might not be a problem, acoustically. However, it might also be an issue visually...

Ok, thanks.

I need all I can get. In order to maximize headroom, I was planning to suspend the ceiling drywall from resilient channel (or something like it) rather than put up new joists on top of the new walls

Assuming that you are not aiming for very high levels of isolation, that probably is your best option. I would go for two layers of 5/8" drywall with Green Glue in between, hung from RSIC clips with hat channel. Another option might be one layer of 3/4" OSB or MDF on the RSIC+Hat Channel, then a layer of 5/8" drywall, also with Green Glue.

Yeah, I'm thinking the OSB is a good idea, too. I always make a mess with drywall anchors, and most of the house is lath & plaster which is an even messier PITA - it would be nice to have at least one place in the house where screwing something into the wall/ceiling would be easy.

But back to the subject of joists: do you happen to know if there are any products I could use to replace the crossbraces that would serve the same function but give me a little more room in which to interleave new joists? Honestly, I'm having difficulty even conceiving of what such a product would look like - the best I can come up with is some kind of metal bracket in the shape of an upside-down U. I'm going to have to replace the existing braces anyways (several are popping out as it is, none have enough room above them to allow additional drywall to be applied to the subfloor), so I'm open to options.

From your diagram, it seems like you are still missing the point: The entire room is a two-leaf system. You build it as "one room inside another room". At present, you are not showing that. You have an outer-leaf wall on the right hand side of the room that you can use, but you also need the walls on the other three sides to complete the outer-leaf shell.... Then you build the actual inner-leaf control-room within that shell.

I think it's not so much that I'm missing the point as it is that, due to the sometimes-funky geometry of the space, I'm unsure of what combination of walls qualify as a 2-leaf system and what ones would wind up being 3 or 4-leaf systems.

To illustrate:

Stuart2LeafPath.PNG

In this model you provided (thank you for that, btw), I see two paths by which sound can travel from the left room to the center room. The blue path obviously traverses a 2-leaf system. But as far as I understand things, the red path crosses 4 leaves. Is that not correct? Or is it correct, but somewhat irrelevant since the blue path is really the one to worry about?

This question concerns me primarily because of the area around the bottom of the stairs, and the paths sound can take through that area:

2LeafPaths_Orig.jpg

The blue path is sound between the booth and the CR through the walls, the red path is sound between the booth and CR through the doors, the green path is sound between the CR and the neighbor's basement, and the yellow path is the sound between all of the studio and the first floor via the stairs (there is a door at the top of the stairs that is not shown in the model).

As far I understood things, on the green path, the CR door/walls would constitute one leaf and the foundation wall would be another. On the yellow path, the CR walls would constitute one leaf and the door/walls at the top of the stairs would be the 2nd.

Is that not correct? Are the leaves too far apart on the yellow, green, and maybe red paths to effectively function as leaves? Is there something else I'm missing?

[Soundman2020]

But back to the subject of joists: do you happen to know if there are any products I could use to replace the crossbraces that would serve the same function but give me a little more room in which to interleave new joists? Honestly, I'm having difficulty even conceiving of what such a product would look like - the best I can come up with is some kind of metal bracket in the shape of an upside-down U. I'm going to have to replace the existing braces anyways (several are popping out as it is, none have enough room above them to allow additional drywall to be applied to the subfloor), so I'm open to options.

That's a pretty major modification you are talking about there! Nobody here can help you with that. You will need to call in a structural engineer to analyze the situation, and recommend a solution. This is a big job, and you CANNOT do it yourself without qualified professional help. Playing with the structure of your house is a very dangerous thing, unless you are a qualified structural engineer... in which case, you would not be asking that question!

Don't do anything structural to your place until you have the engineers report and recommendations, in writing. Not only could you get yourself killed or injured, but it is also illegal, and you would lose your homeowners insurance, without any doubt, making you legally liable for all damages that anyone else might suffer. Not a good idea!

- Stuart -

[Soundman2020]

I think it's not so much that I'm missing the point as it is that, due to the sometimes-funky geometry of the space, I'm unsure of what combination of walls qualify as a 2-leaf system and what ones would wind up being 3 or 4-leaf systems.

To illustrate: ... In this model you provided (thank you for that, btw), I see two paths by which sound can travel from the left room to the center room. The blue path obviously traverses a 2-leaf system. But as far as I understand things, the red path crosses 4 leaves. Is that not correct? Or is it correct, but somewhat irrelevant since the blue path is really the one to worry about?

That's not how it works. MSM systems are not separate walls, where sound goes through one leaf, gets attenuated a bit, then goes through the other leaf and gets attenuated some more. An MSM system is a tuned system, that acts as a whole, not as individual parts. The entire system, consisting or both leaves, and the air between them, and the damping material in the air space, all act together as a single unit. Sound is affect by that one single unit, not by the individual parts. The whole is greater than the sum of it's parts.

In other words, you are not thinking about this the right way. You do not have multiple paths going in and out of your room, with different isolation on each part: Rather, you have an isolated room that acts as a unit, and sound is either "inside" or it is "outside". The room acts the same, if it is built correctly. It would only act the way you show in your second diagram if it is built very badly, and not built as an MSM system.

This question concerns me primarily because of the area around the bottom of the stairs, and the paths sound can take through that area:

Sound from outside the room can only take one single path to get in, and that is "through the MSM system". It cannot take multiple paths to get in, since there are no such paths in a resonant system (if you build it correctly).

The blue path is sound between the booth and the CR through the walls,

That area is built incorrectly. It is a three leaf system, while the rest of the CR is only a single leaf system. You do not have a 2-leaf MSM system like that. There would basically be no isolation at all if you build it like that.

Is that not correct? Are the leaves too far apart on the yellow, green, and maybe red paths to effectively function as leaves? Is there something else I'm missing?

You are missing how MSM isolation works! Search for the Wyle report from way back in 1973 and read through that, to get an understanding of how it works. The key is to forget the erroneous concept that sound goes first through one part then through the other: it does not. It goes through the system. The second key is to understand that it is a resonant system that is tuned to resonate loudly at a certain frequency, which must be below the audible spectrum, and that it blocks sound increasingly well at all higher frequencies, except at the region of the "coincidence dip", which is an entirely different effect at a much higher frequency than where MSM takes place.

Think of it this way: The wall is a band-pass filter. It allows through sounds at a certain frequency, and blocks all others. Period. Saying that some sound goes through one path and some goes through another is just as invalid as saying that in the EQ circuitry of the bandpass filter, some sound goes through the resistor, some through the capacitor, some through the resistor, some through the wiring between them, and some through the op-amp. It simply does not work like that. A bandpass filter is a tuned circuit that affects different frequencies in different ways, as a unit. It does not provide several paths for sound to get through: it provides only one single path that allows some frequencies through better than others.

Unless you design your studio as a proper fully-decoupled two-leaf MSM system, correctly tuned, you will not get good isolation.


- System -

[DanCostello]

Hi Stuart,

That's a pretty major modification you are talking about there! Nobody here can help you with that. You will need to call in a structural engineer to analyze the situation, and recommend a solution. This is a big job, and you CANNOT do it yourself without qualified professional help. Playing with the structure of your house is a very dangerous thing, unless you are a qualified structural engineer... in which case, you would not be asking that question!

Don't do anything structural to your place until you have the engineers report and recommendations, in writing. Not only could you get yourself killed or injured, but it is also illegal, and you would lose your homeowners insurance, without any doubt, making you legally liable for all damages that anyone else might suffer. Not a good idea!

Really? Because everything I find suggests that replacing the cross-bracing is a pretty minor job and that, unless you pull out all of them and leave them out for a long time (which I wouldn't do), it's fine. They serve primarily to keep the joists from twisting over time, not so much to enhance the total loadbearing capacity of the floor/ceiling. Apparently, many older houses didn't even have this bracing and adding it is a common modification to stiffen floors to stop them from bouncing or squeaking. It also appears to be common to remove at least some braces in order to make room for air ducts.

My plan was to do what Rod Gervais describes in his book (fig 4.21 in my copy, the 2nd edition) to beef up the mass of the ceiling by adding drywall to the underside of the upstairs subflooring. In that plan, the crossbraces get in the way of the drywall, so he recommends removing them, adding the drywall, and then reinstalling new braces that better fit the altered space.

From what I'm gathering, vertical blocking between the joists (i.e. a solid blocks instead of diagonal strips) provides even better resistance to flexing and twisting than do the diagonal strips, but often isn't used because it prohibits plumbing and wiring from being run between the joists. I don't care about running anything in the ceiling, so that's not a problem for me, and blocking would be easier for me to install than the strips.

[DanCostello]

That's not how it works. MSM systems are not separate walls, where sound goes through one leaf, gets attenuated a bit, then goes through the other leaf and gets attenuated some more. An MSM system is a tuned system, that acts as a whole, not as individual parts. The entire system, consisting or both leaves, and the air between them, and the damping material in the air space, all act together as a single unit. Sound is affect by that one single unit, not by the individual parts. The whole is greater than the sum of it's parts.

In other words, you are not thinking about this the right way. You do not have multiple paths going in and out of your room, with different isolation on each part: Rather, you have an isolated room that acts as a unit, and sound is either "inside" or it is "outside". The room acts the same, if it is built correctly. It would only act the way you show in your second diagram if it is built very badly, and not built as an MSM system.

Ok, I think I understand it better now. Thanks for the heads-up on the Wyle report; the electrical circuit concept makes sense. I think I may have been tripped up by warnings in other threads against adding too many walls or other barriers and inadvertently creating systems with more than 2 leaves. Of course, I can't seem to find those at the moment to figure out what I misunderstood...

If I'm understanding things correctly now, you're saying I would be better off adding leaves along the path I've traced here in teal, so that each of those walls is a legit 2-leaf wall system on its own:

2LeafPaths_NewLeaf.jpg

Of course, the doors are going to pose challenges to this, since I don't have room for double doors. I guess I'll definitely have to go with a super door.

Trying to hang drywall between the studs and the stairs is going to be a challenge, too, but may be feasible.

The blue path is sound between the booth and the CR through the walls,

That area is built incorrectly. It is a three leaf system, while the rest of the CR is only a single leaf system. You do not have a 2-leaf MSM system like that. There would basically be no isolation at all if you build it like that.

The right-most leaf along that blue path (i.e. the one that looks like a 3-segment arc) are the speaker soffits. If understand your other posts correctly, speaker soffits only kinda-sorta constitute a 3rd leaf and often aren't worth worrying about. Is that correct, or am I misunderstanding that, too?

[DanCostello]

I think I've figured out the best way to build the 2-leaf walls AND install double doors all around, but I'm still waiting for the floor leveling to be finished, which will affect some of the elevations and, thus, some of my way-less-margin-than-I'd-prefer framing (which I've mostly modeled), so I'm going to hold off on finalizing that for the time being and move on to HVAC design in the mean time.

My original idea/hope was to add a second zone to the single-zone system I already have covering my 1st and 2nd floor. I mean, why add extra gear if I can tap into what I already have, right? Well, I've had a few hvac contractors in over the last week (and have one more coming Monday), and every single one of them was adamantly against that plan. Each one said that going that route, I'd spend more money to get results I wouldn't be happy with - assuming my current equipment could handle it in the first place, which was in no way a given.

Most of them recommended a typical ductless mini-split, which cools and also provides enough heat for what I'd need, but doesn't handle fresh air. I forgot to press Guy #1 about the fresh air issue, but when I pressed Guy #2 on it, he told me repeatedly that the ductless mini-split would be enough. That's absurd, so no matter what I do, Guy #2 is off the list.

Guy #3, though, had an option I wasn't aware existed: a ductED split system, with an air handler, like the ones here:
http://www.lg-vrf.com/indoor-units-ducted.aspx

Price-wise, it's really reasonable. Guy #3 quoted me a 2-zone ducted split system for only about 10% more than Guy #1 quoted for a single-zone ductless system, and about 30% less than Guy #1 quoted for a multi-zone ductless system. If I can cover the whole space for not much more than one room, then hell yeah.

But I'm still a little unclear on where in the system the cassettes get installed. Most of the literature I've seen describes the cassettes as "concealed" and it seems typical to install them in ceilings, but then they typically have changeable air filters, from which I infer that they need to at least be somewhat accessible, right? How are they accessible in a ceiling unless it's a drop ceiling? The need for accessibility would affect my placement of them.

What I haven't been able to find, though, is how much ductwork is supposed to exist downstream of the cassettes. Most installation examples have them directly above (or built into) the air registers. I don't want to do that because it would impact my ability to built silencers boxes correctly. Are they able to drive, say, 20' of duct? Could I have these installed near my air handler (which would be next to the computer rack, furnace, and water heater), outside of my outer leaves, and have them feed the ductwork that then supplies the rooms? Would I have to install the cassettes inside the inner leaves? Between the leaves?

Thanks,
-Dan.

[Soundman2020]

but when I pressed Guy #2 on it, he told me repeatedly that the ductless mini-split would be enough. That's absurd, so no matter what I do, Guy #2 is off the list.

Yup, for sure! Very strange...

Guy #3, though, had an option I wasn't aware existed: a ductED split system, with an air handler, like the ones here:

Yup. I often use those in my designs. You can position that unit outside your isolation shell, and have really quiet HVAC. No noise at all inside. Guy #3 seems to be on the ball!

Price-wise, it's really reasonable. Guy #3 quoted me a 2-zone ducted split system for only about 10% more than Guy #1 quoted for a single-zone ductless system, and about 30% less than Guy #1 quoted for a multi-zone ductless system.

Sounds about right, yes.

But I'm still a little unclear on where in the system the cassettes get installed.

What "cassettes"? Not sure what you mean by that. Your link does not show cassette units: it shows ducted AHUs, which are very different things.

Could I have these installed near my air handler

Now you are REALLY confusing me! The unit you linked to IS an AHU! It does not need to be connected to any other AHU, nor does it need to be connected to any "cassettes". It just needs to be connected to the ducts that service your studio.

The way I normally do things with a ducted AHU, such as what your link shows, is as I mentioned above: I keep it completely outside of the isolated area (outside the outer-leaf, so to speak), where it can be as accessible as you like. You just run your supply and return ducts through both leaves of your isolation system, using silencer boxes of course, and that's it. You can have full access to the AHU for changing filters, maintenance, repairs, replacement, etc. without ever needing to do anything inside your studio. That's why I like these so much.

Are they able to drive, say, 20' of duct?

The unit you linked to is billed as "High Static", so yes, it can handle a good length of duct. You'd have to figure out what the static pressure of your ducts, silencers, registers and filters will be, then compare that with the maximum rated static pressure of the unit you choose. As long as the static pressure of your complete duct system is lower than the maximum that the AHU can handle, then you are fine.

Would I have to install the cassettes inside the inner leaves? Between the leaves?

I still don't get what "cassettes" you are talking about. Please elaborate.


- Stuart -

[DanCostello]

Now you are REALLY confusing me! The unit you linked to IS an AHU! It does not need to be connected to any other AHU, nor does it need to be connected to any "cassettes". It just needs to be connected to the ducts that service your studio.

<snip>

I still don't get what "cassettes" you are talking about. Please elaborate.

Thanks for the comments, Stuart.

Yeah, at the time I wrote that, I was a bit confused on exactly how these systems were supposed to work. I thought each system had both a vertical air handler and one of the ceiling units (which is what I was describing with the term "cassette"). I didn't realize that they're both variations on the same thing and that you use either a vertical air handler or a ceiling air handler.

Sounds about right, yes.

I'm glad that sounds consistent with your experience. Since only one firm quoted a system like this, and since it was so close to the price of the more commonly-spec'd ductless systems, I was a little skittish that the price was a little too good to be true.

Though, given how much of a hassle the floor-leveling is turning out to be (solely through incompetence on the part of the contractor), maybe I'm due for some good karma.

The way I normally do things with a ducted AHU, such as what your link shows, is as I mentioned above: I keep it completely outside of the isolated area (outside the outer-leaf, so to speak), where it can be as accessible as you like. You just run your supply and return ducts through both leaves of your isolation system, using silencer boxes of course, and that's it. You can have full access to the AHU for changing filters, maintenance, repairs, replacement, etc. without ever needing to do anything inside your studio. That's why I like these so much.

Fantastic.

Are they able to drive, say, 20' of duct?

The unit you linked to is billed as "High Static", so yes, it can handle a good length of duct. You'd have to figure out what the static pressure of your ducts, silencers, registers and filters will be, then compare that with the maximum rated static pressure of the unit you choose. As long as the static pressure of your complete duct system is lower than the maximum that the AHU can handle, then you are fine.

Ok cool. I guess I have more numbers to run, then.

-Dan.