Feasibility of Isolating Studio Above Attached Garage

#31

Onto the exterior aluminium window frames, here is my first design proposal. I'm looking at 6063 Aluminum for the frame construction which would be powder coated white. My fabricator and I came up with a three piece design that would sandwich the 5/8th laminated glass pane. The pane would sit in neoprene / rubber setting blocks on three sides. Note that piece C sits inside piece B.

My fabricator says he cant weld pieces A and B together for risk of warping so I'm considering using rivets to fasten these two pieces together. I'm considering using either butyl tape or 3m VHB tape (or both) to make a water tight assembly.

1. Is rivets the best way to fasten pieces)A and B?
2. Is Butyl tape / VHB tape a good option for sealing?

As for the Setting Blocks.

3. Are they required on all 4 sides of the glass?
4. Would it be best to have continuous neoprene bands as opposed to the block pieces shows?
5. Would it be preferable to use glazing tape (VHB structural glazing tape) where the glass faces piece B and C, putting setting blocks only on the perimeter of the pane?
6. Would the powder coat affect adhesion?

#32

rivets or bolts (being aware of metal interactions between aluminum and steel when in the presence of water). use a thick rubber seal all around the glass in place of set blocks, otherwise there is a risk of air gaps and moisture, insects etc.

#33

another option (and you see this in commercial windows) - the main part of the frame if solid and stiff, then a lighter part of inserted which applies pressure to the seal. see picture. the stiff outer frame is assembled as either 2 or (more commonly) 4 pieces which tensions the lighter part as the sections are tightened together. so basically - attach the bottom and siides, slide in the laminated glass and the light portion, then attach the top.

#34

gullfo wrote:rivets or bolts (being aware of metal interactions between aluminum and steel when in the presence of water). use a thick rubber seal all around the glass in place of set blocks, otherwise there is a risk of air gaps and moisture, insects etc.

Seems like VHB structural glazing tape would be my best bet for a permanent water tight seal without rivets or bolts. As for the use of set blocks, all gaps would be caulked and sealed of course, but I see how placing it all around would be better.

#35

gullfo wrote:Source of the post another option (and you see this in commercial windows) - the main part of the frame if solid and stiff, then a lighter part of inserted which applies pressure to the seal. see picture. the stiff outer frame is assembled as either 2 or (more commonly) 4 pieces which tensions the lighter part as the sections are tightened together. so basically - attach the bottom and siides, slide in the laminated glass and the light portion, then attach the top.

Not sure I follow, I'm having a hard time visualizing what you are describing.

#36

if you check out commercial products like Marvin, Andersen, Pella, etc etc - their metal frame products use a frame set which has a stiff section which is what attaches to the structure, and a "spring" frame part which holds the glass securely against the seals on the stiff frame. the frame parts need to be assembled - using corners and span sections or simply span sections which as some exterior shell added etc.

#37

Here is the 2nd draft of my baffle boxes and ducts. Baffles built with 3/4" birch plywood and 2" Duct board. I'll be working mostly alone so I'll run my Panasonic Intellibalance FV-10VEC2 ERV at 50CFM (low setting) most times. The ERV has 6" ins and outs so I will use 6" flexible ducts between the ERV and outer leaf baffles boxes.

The cross sectional area (CSA) of the 6" duct work is 28.3 in^2. The baffle boxes have a CSA of 83 in^2 so the air velocity should drop by roughly 3x inside the baffles. On the supply side, at the output of the inner baffle, existing construction geometry will force me to use two short (as possible) runs of 6" duct.

These two 6" supply ducts now enter the triangular space (above the collar ties and below the roof truss) at both sides of the central ridge beam.

I will be making two supply paths at either side of the ridge beam to further reduce air velocity and for symmetrical finishes.

As for finishes, below the collar ties, I plan on exposing the coated side of the 2" duct board. The Owens Corning duct board I will be using has similar acoustic characteristics as 2" 703. Above the duct board the space between the collar ties will be filled with pink FG batts.

Now here is where I have some questions. The way I see it, I have 4 ways that I could get from the two short 6" supply ducts to the two 8" supply diffusors (2x 8" round diffusors for a total of 100 in2 of area)

1 - Easiest: (2x) 8" Flexible round duct up to both diffusors. Triangular space above collar ties filled with pink FG. This would give 104 in^2 total CSA in the supply paths for an air velocity reduction of 3.67x
2 - Lower air turbulence: (2x) 8" Rigid round duct up to both diffusors. Triangular space above collar ties filled with pink FG. This would give 104 in^2 total CSA in the supply paths for an air velocity reduction of 3.67x

3 - Best LF absoption(?) (2x) Rectangular ducts built with 2" duct board to both diffusors. Remaining volume of the triangular space filled with pink FG. This would give 98 in^2 total CSA in the supply paths for an air velocity reduction of 3.45x

4 - Lowest air velocity (2x) Triangular ducts built with 2" duct board up to the two air diffusors, but this time leaving no void for pink fluffy FG. 242 in^2 total area.

Questions
1. How do the static pressures of my proposed ducts play into this? I'm still unclear about how to factor that in. My ERV has variable fans that are supposed to compensate for varying static pressures in order to maintain selected CFM.
2. LF Absorption: Would option 3 have the best bass trapping ability?
3. Diffusors: The diffusors in these drawings are inexpensive ones from Grainger. I've looked into the ones suggest by Rod Gervais from Nailor, but they seem overkill for my needs. Any other kind of diffusors I should be considering?
https://www.grainger.ca/en/product/CEILING-DIFFUSER-WHITE-10-DUCT-SIZE/p/WWG52CE94?analytics=prodRecs&cm_sp=HP-_-RV-_-NA-_-PR-_-NT-NA-_-EN
4. Is my assumption correct that it should be the supply air (not return air) that should be ducted closer to my mini split condenser unit?
5. Would higher density rock wool be better for LF absorption versus pink FG above the lowest layer of ductboard? IE between and above the collar ties.

I will make a separate post about the return ductwork shortly.

Thanks!

#38

use the flex duct (as large as you can make it) from the silencer to the vents and fill around them with the pink stuff. the friction after the silencer is minimal with flex and being flex will allow the LF absorption to work through it and around it.

place supply vent nearest your AC handler.

perforate the hard side of the duct board to allow better air flow through it.

any low noise vent should be ok given the proximity to the air handler and the size of the ducts.

#39

One thing I forgot to ask about is static pressure. I understand what static pressure is, but I'm not sure how to factor it into my design. I know the ERV I'm looking at has variable DC motors which are supposed to compensate for static pressure increases in order to produce the selected CFM value. I know all those 90s in my baffles are sure to increase static pressure.

Do I need to try to figure out what the actual static pressure of my setup will be and compare that to what my ERV can handle?

#40

The 90° turns matter yes. Here's a quote from a post on another thread about how I calculated the pressure loss for one of my silencers. Plug in your own values taking special care of the different measurement units involved. Here's a direct link to the post, and the thread also has some good information from others on exactly this topic: viewtopic.php?p=5800#p5800

Silencer box flow calculations using the equivalent duct length method:
Cross section area of silencer is 18*20 = 360cm2
Equivalent diameter is 21.41cm = 8.43"

Equation for converting a sharp 90 degree bend into an equivalent length of straight duct is: Duct Diameter x 60

8.43” x 60 = 506” or 42’ for each 90 degree turn

x 8 for each silencer = 336 feet of straight duct

Using the engineeringtoolbox.com friction or head loss calculator this results in;
https://www.engineeringtoolbox.com/duct ... d_444.html

Friction Loss (inH2O): 0.0618
Friction Loss (inH2O/100 ft): 0.0184
Air velocity (ft/min): 282
Air velocity (ft/sec): 4.7

It's worth noting that this is just a model, but in my limited experience using it, it tallied well with reality.

Cheers!
Jennifer

#41

Hi folks. I will be focussing on this project full time again come December. Right now I'm still working out a few details regarding the outer leaf baffle box locations. I'm wondering if I can use some the space above the walk-in closet, where the outter leaf baffle box and ERV are located, to create some bass trapping there.

In an MSM wall, if the air gap were to be made very deep, like 32" to 48" deep, and completely filled with FG batts, would it also act as a bass trap?

Forgive the crude drawing but I'm thinking something like this:

#42

are you saying the space where the two silencers connect? - if you isolate that duct/path from the room and only one room is using that space, and that space is isolated as well - then you could use it as additional absorption for a room (much like you would a closet).

#43

What I mean is this. In that picture the blue member is the top plate of the inner wall, the green member is the top plate of the outer wall. The space in between is the air gap of the MAM. Yes this is where the inner and outer baffles will connect. Everything will be sealed accordingly.

As opossed so adding broadband absorption / bass trapping on the inside of the of the blue wall, if I move the green wall and outer baffles back 36" or so towards the ERV (in white on the right side of the picture), will the air gap inside this MAM setup act as bass absorption if I filled it with FG batts?

Im just trying to use the space where the ERV as efficiently as I can, since I have some room to move the green wall out towards the ERV, it would be great to have the benefit of LF absorption without having to also punch out the blue wall also.

#44

sure - move the ext silencer closer to the ERV. then i'd put the in-room silencer in that new wider space since that will be open to the room and then run the ducting in the room via a soffit. i would open it for best absorption rather than just dead air space. a closet... with a really big absorber in it...

#45

gullfo wrote: i would open it for best absorption rather than just dead air space. a closet... with a really big absorber in it...

What is it that I should open? Are you referring to the soffit that would have the additional ducting?

Soundman2020 - Studio Design Forum