The No.1 Website for Pro Audio
Question On Converting Garage To Studio/Rehearsal Space
Old 7th February 2020
  #31
Lives for gear
 

Quote:
This shows garage door is a leaf. Its a panel, and has the mass of a sheet of drywall.
A panel might well be a leaf, but there's no MSM resonance of the air between that panel and the next leaf is not enclosed and compressible. That's what the "S" in MSM stands for: spring. If the air cannot be compressed to act like a spring, then it is not a spring. Look up "bulk modulus" to see how this works.

Or just do a simple experiment: get yourself a bicycle pump, and put your finger over the nozzle. Press on the handle, and what do you get? Compression. You compress the air inside the body of the pump, and it is now "bouncy" and "spring"... because it is contained. As you push down on the handle, you can feel the resistance: th air pushes back, "springily". Your finger prevents the air from leaking out, so it can be compressed. Thus, it is a spring. Now take your finger off the nozzle, and press the pump handle again: Now what happens? The air hisses out of the nozzle, and there is no more "spring"! The handle moves up and down with very little resistance now.... the air spring is gone, because it is no longer contained, and no longer compressible.

Same thing with MSM: if the air in the cavity is not contained, it can't be compressed, and there is no spring.

Quote:
Over ten years in construction and ive never seen drywall installed per USG spec air sealed, with backer rod and caulking. Commercial or residential. It would be a specialized case where you would see this.
And yet, the effect is there... Even in poorly built walls, there is enough resistance to the movement of air to create a spring. Perhaps not a very good one, but it is still there... unless you do something on purpose to prevent it from being there...

Quote:
So, again your reasoning that the massive panel isn't a leaf because its not 100% sealed, is just not right. Your interpretation is wrong.
And yet, the construction is there, and complete, and isolates well, performing as a 2-leaf system, not a 3-leaf...

Quote:
Your door plug creates a 3 leaf system when a new wall is built in front.
And yet, in reality it is not a 3 leaf system.... You can imagine and hope any hypothesize all you want about that wall, but the fact remains is that you didn't design it, you didn0t build it, and you have no idea how it actually performs. You are guessing... and guessing wrong.

Quote:
As far as the pics go, whatever semantic game your playing is laughable.
You might want to try actually looking at them, to see where you are going wrong. It's clear as daylight, and there is nothing about "semantics" at all. Just look!

Quote:
If that's not sheathing, what is it? Its certainly not the insulated, exposed joist wall frame that is the outer leaf of a two leaf system
Ummm.... actually, yes it is. Take a closer look. The studs are visible....

Quote:
Since the exterior wall needs to be sheathed to function, the interior must be open and unsheathed. Your pictures do not show this.
Ummm... yes they do. Take a closer look. You keep on wanting to tell me how that wall MJST have been built, in order to entertain your fantasy, but if you actually take the time to look, you'll see that your fantasy is false, and collapses in a heap on the floor.

That is not a 3-leaf wall.

Quote:
No matter how close one looks, they wont find an unsheathed, exposed joist wall cavity.
Then I guess you aren't looking close enough!

Quote:
Aside from that even if the pics were proper, your plug goes leaf, insulated cavity, leaf. This leaves no room for further walls in front without increasing the leaf count.
Leaf count is irrelevant if there is no air spring. If all you have is Mass --- Mass, with no spring in between, then you do not have MSM.


Quote:
If your idea was an effective solution we would leave existing drywall on typical walls sheathed on both sides, then build the new wall in front... We (people who build real studios, properly) don't do that
So you are implying that I do not build studios properly? This conversation is over. Good bye.

Quote:
so this is not personal.
Yes it is. You just made it personal, by claiming that the studios that I design and build are not "built properly". That's insulting, and personal. So, as I said: This conversation is over. Good bye.

- Stuart -
Old 7th February 2020
  #32
Lives for gear
 
Starlight's Avatar
 

Quote:
Originally Posted by Jag94 View Post
So maybe there is more than one way to skin this cat.
Yes and no.

NO

If you understand the principles, such as the MSM system Stuart talks of in the post above, then these cannot be skinned any other way because they are the basic principles, the theory, the result of testing and measuring and finding what can reliably be repeated - which is what science is.

YES

How you use that principle can be skinned many ways. For example, the garage door that is left in place has gaps around all edges and as such cannot be a leaf, whereas, as you mentioned, what if you seal the door in place, making it airtight? It then is a sealed leaf and can be part of a MSM, so the garage door will or will not be a leaf depending on how you skin your cat, ie. whether you leave it with gaps or seal it airtight.
Old 7th February 2020
  #33
Lives for gear
 
Kyle P. Gushue's Avatar
Lets lay this myth Stuart is spreading to rest right here. Rod indicates in several posts, as well as his book ed.2. That a ventilated panel like a roof or wall with a vent, is in fact a leaf.


Stucco Garage Build: To Build 2-Leaf Wall OR Layer Existing Wall Frame?

soundproofing - inbetween studs??

Room within a room outer shell question

https://homerecording.com/bbs/genera...indows-266820/


OP (partial quote)

"PS. so you know the inner wall is 1 sheet of 5/8 drywall with insulation behind. The outter wall is 3 sheets of 1/2 inch drywall with green glue. The exterior wall is plywood & hardey plank. The plan is to vent the ext. wall to avoid the three leaf thing."

Rod (partial quote)

"I wish you had spoken to us as to your plans before building - even with venting of the outer wall - you still have a 3 leaf system - that's a shame.

Rod"
Old 12th June 2020
  #34
A little update.

I am still in the early stages of the build. I'm currently "beefing up" the external leaf. It is moving along, albeit slowly, since it's just me doing all the work. Also doesn't help that it's been 100 degrees here the past few days.

Speaking of heat... do I need to ventilate my roof? I can't seem to find the answer to this question. The garage is just one room, with an "A" frame gable roof. The new inner leaf will also be an "A" frame design. I'll post a picture of my mock-up in sketchup.

@ Kyle P. Gushue , I read through THIS thread on john sayers site, and the guy who did this build made the garage door part of the outer leaf like you suggested. I have decided to go with this design rather than building a separate "outer leaf". So I will be bolting the garage door in place, adding foam to the inner bays of the door, then building a wall with OSB and pushing it RIGHT UP against the door so there is no gap. In doing this, where do I need to put a moisture barrier? I live in SoCal.

EXTERIOR FRAME

Both Frames

Last edited by Jag94; 12th June 2020 at 03:15 AM.. Reason: To add pictures
Old 12th June 2020
  #35
Lives for gear
 
Kyle P. Gushue's Avatar
Quote:
Originally Posted by Jag94 View Post
A little update.

I am still in the early stages of the build. I'm currently "beefing up" the external leaf. It is moving along, albeit slowly, since it's just me doing all the work. Also doesn't help that it's been 100 degrees here the past few days.

Speaking of heat... do I need to ventilate my roof? I can't seem to find the answer to this question. The garage is just one room, with an "A" frame gable roof. The new inner leaf will also be an "A" frame design. I'll post a picture of my mock-up in sketchup.

@ Kyle P. Gushue , I read through THIS thread on john sayers site, and the guy who did this build made the garage door part of the outer leaf like you suggested. I have decided to go with this design rather than building a separate "outer leaf". So I will be bolting the garage door in place, adding foam to the inner bays of the door, then building a wall with OSB and pushing it RIGHT UP against the door so there is no gap. In doing this, where do I need to put a moisture barrier? I live in SoCal.

EXTERIOR FRAME

Both Frames
Building code most likely requires the exterior roof to be ventilated. Rod covers this in the book, citing a couple options. There is a thread on Sayers site where rod chimes in about it. You will likely want to not do any beefing up on the roof until your plan there is completed.

As far as the vapour barrier on the garage door, i am not sure, im over in Massachusetts, and codes are different here. I know in general the paper backing for fluffy insulation is a vapour barrier, but i am not sure if the cavity for the door will have it, or if it meets code regulations.

Having done thousands of sqft of "beefing up" i feel your pain, there is no fast way to do it. It is however rewarding.
Old 14th June 2020
  #36
Quote:
Originally Posted by Kyle P. Gushue View Post
Building code most likely requires the exterior roof to be ventilated. Rod covers this in the book, citing a couple options. There is a thread on Sayers site where rod chimes in about it. You will likely want to not do any beefing up on the roof until your plan there is completed.
I skimmed through the book again last night, and couldn't find anything on venting the roof. Maybe I have the 1st addition, and it was added to the 2nd addition?

I'll do some searching on the Sayers site.

Thanks dude.
Old 14th June 2020
  #37
Lives for gear
 
Kyle P. Gushue's Avatar
Quote:
Originally Posted by Jag94 View Post
I skimmed through the book again last night, and couldn't find anything on venting the roof. Maybe I have the 1st addition, and it was added to the 2nd addition?

I'll do some searching on the Sayers site.

Thanks dude.
Yes 2nd edition pg. 283 on my kindle version, titled "dealing with existing roof structures"

I don't seem to have the Sayers link in my list of links. Ill post it if it turns up.


Here rod talks about a garage roof on GS:
Room within a room outer shell question
Old 19th June 2020
  #38
@ Kyle P. Gushue Yeah it looks like I'm going to need to install a ridge vent, and soffit vents, and create a 3-leaf roof... although the consensus is that because it is so heavily vented, the roof almost doesn't count as a leaf. I will then need to add a new exterior leaf up against the rafter faces, which will create a slight problem due to the large gussets i need to make for structural integrity. Oh boy this is gonna be fun.
Old 19th June 2020
  #39
Lives for gear
 
Kyle P. Gushue's Avatar
Quote:
Originally Posted by Jag94 View Post
@ Kyle P. Gushue Yeah it looks like I'm going to need to install a ridge vent, and soffit vents, and create a 3-leaf roof... although the consensus is that because it is so heavily vented, the roof almost doesn't count as a leaf. I will then need to add a new exterior leaf up against the rafter faces, which will create a slight problem due to the large gussets i need to make for structural integrity. Oh boy this is gonna be fun.
Why do you have to have both soffit and ridge vents, code? Have you explored the venting method in the book that describes a material between sheething and roof shingles? When all is said and done it might end up easier, cheaper and better.

There's a product also in the book that goes in the wall bays to maintain ventilation, its a 3 leaf scenario, but worth considering.

I would think deeply about this, before making a decision. Probably worth contacting Rod about. But either way id consider all options from a performance, materials and labour perspective.

Im having trouble picturing the gussets. Is that the only way to reinforce the structure?

It might not be as bad as it seems currently...

Here Rod explains that a ventilated roof is still a leaf. Think of the proportion between vent and sheathing. If it wasn't mostly sheathing, it wouldn't be a very good roof.

https://homerecording.com/bbs/genera...indows-266820/


Here rod explains where to locate mass when dealing with 3 leaf scenarios.

https://www.gearslutz.com/board/showpost.php
Old 19th June 2020
  #40
Quote:
Originally Posted by Kyle P. Gushue View Post
Why do you have to have both soffit and ridge vents, code? Have you explored the venting method in the book that describes a material between sheething and roof shingles? When all is said and done it might end up easier, cheaper and better.
So there needs to be a path for air to travel under the roof deck. My soffit's are completely closed off, so if I create a ridge vent, it won't do anything because there will be no air to get to it.

Check out this graphic. It basically shows what I'm describing.

RIDGE VENT

The product that Rod mentions is a basically a way to guide the air from the soffit to the ridge vent, but also allows you to put insulation in the ceiling. It's called a rafter vent. Here is a link to home depot

Rafter Vent

You need all 3, the soffit vent for air to enter, the rafter vents to guide the air up the inside of the roof, and then the ridge vent to allow the air to escape. I actually don't think it's going to be as difficult as I originally thought. I just have to grow some balls and get on the roof to do the work.


Quote:
Im having trouble picturing the gussets. Is that the only way to reinforce the structure?
So I learned that the lower the pitch of your roof, the more important it is to support the roof with the added weight, or if you're raising the ceiling (which I'm doing both.

Right now, there are 4 ceiling joists that are stopping the walls from leaning (resulting in the roof collapse). Here is a sketch to illustrate...

Ceiling Joists


I want to remove those because they are low, and I want to raise the ceiling of the inner frame. But to do that, I need to reinforce the roof. My Structural engineer gave me a design for how to do that. I need to install rafter ties on every rafter no less than 2 feet from the ridge peak, and plywood will be installed on both sides of each rafter. Here is the design

Rafter Tie Design

I'm working with him to tweak it, as I'm not completely sold on it as is, but it's complicated and I don't want to get into it, haha.

These gussets allow me to add weight to the existing roof, as well as raise the overall ceiling height.
Old 19th June 2020
  #41
Lives for gear
 
Kyle P. Gushue's Avatar
I appreciate the reply, ill check it out when i have a few minutes to concentrate.

But fiy this was what i was referring to, about the vent between sheathing and shingles. (Pg 284 on my kindle) i could see it potentially being easier/cheaper than going 3 leaf.

------

"There are pretty much two options that exist. You can deal with this on top of the roof, or you can live with a three-leaf system and construct the assembly with the intent of overcoming the issue. Dealing with this outside of the building envelope would be the best option, and it is easy enough to incorporate into your work if you are constructing a new building. Simply add all the mass you want (within structural limitations, of course) and then insulate the top of the roof with insulating panels made for this purpose, add your shingles or other roofing material, and you now have a mass leaf that does not require ventilation below."
Old 19th June 2020
  #42
Quote:
Originally Posted by Kyle P. Gushue View Post
Dealing with this outside of the building envelope would be the best option, and it is easy enough to incorporate into your work if you are constructing a new building. Simply add all the mass you want (within structural limitations, of course) and then insulate the top of the roof with insulating panels made for this purpose, add your shingles or other roofing material, and you now have a mass leaf that does not require ventilation below."
This is great if I was replacing the roof. This option is for building a new building, or completely redoing the roof sheathing/shingles. But my roof is only like 3 or 4 years old, and is in great condition. So it will be significantly more cost effective to make a ridge vent, and put some holes in the soffit.

The downside, is I will create a 3-leaf roof, which as Rod says many times, is just sometimes one of those real world things you have to deal with.

I have an unrelated question regarding fresh air INSIDE the room. I plan on using an ERV to exchange the air. When it comes to ERV for air circulation, I want to make sure I have this correct. The projected volume of my room will be roughly 1,900 cubic feet. (14x15x9). 1,900/60 puts me around 32 CFM (cubic feet per minute). If my unit can push 40 CFM, is that sufficient? Or am I not calculating this properly?

By the way, I appreciate you asking tough questions. The ability to bounce ideas off of people is very valuable. So thank you!
Old 19th June 2020
  #43
Lives for gear
 
Kyle P. Gushue's Avatar
Quote:
Originally Posted by Jag94 View Post
This is great if I was replacing the roof. This option is for building a new building, or completely redoing the roof sheathing/shingles. But my roof is only like 3 or 4 years old, and is in great condition. So it will be significantly more cost effective to make a ridge vent, and put some holes in the soffit.

The downside, is I will create a 3-leaf roof, which as Rod says many times, is just sometimes one of those real world things you have to deal with.

I have an unrelated question regarding fresh air INSIDE the room. I plan on using an ERV to exchange the air. When it comes to ERV for air circulation, I want to make sure I have this correct. The projected volume of my room will be roughly 1,900 cubic feet. (14x15x9). 1,900/60 puts me around 32 CFM (cubic feet per minute). If my unit can push 40 CFM, is that sufficient? Or am I not calculating this properly?

By the way, I appreciate you asking tough questions. The ability to bounce ideas off of people is very valuable. So thank you!
Fair enough. Im enjoying following this thread.

Id had to double check but i believe the rule if thumb for fresh air return is 15 cfm per person. So you estimate occupancy of the room and multiply the number of people x 15cfm.

Not sure if that's exactly what your asking.
Old 19th June 2020
  #44
Lives for gear
 
Kyle P. Gushue's Avatar
Not trying to argue here, just explore. I totally get the roof is fairly new.

I am still not sold completely that it ends up cheaper compentsating for the 3 leaf system with mass than a roof replacement.

My thinking is that the existing sheathing is wasted mass, plus you need additional layers to compensate for it. Plus your starting from scratch on the middle leaf.

So say it takes 2 layers on the innermost leaf to compensate and you want 2 layers in the middle leaf. (Just for example i don't know how to calculate 3 leaf assemblies).

You could just simply add another layer to the roof and that would omit 3x layers elsewhere giving the same result. Im not sure that those 3 layers outweight the cost of the roof. Roofing is usually pretty fast and low cost. Plus the uncertainty of the 3 leaf isolation value.

Again i totally get your point. I just would want to be certain how much additional mass and labour the 3 leaf costs, relative to a roof resurface.

I can see where if taping and caulking is done diy, the drywall could be cheaper.

I am also *pretty sure* that the additional mass on the interior needs to be the entire space. Maybe @ avare can chime in here.

Imho its worth knowing the cost of both before deciding. And worth a call to someone to calculate it for me.

Just figured id mention it. I wish i was more knowledgable in this topic but ive somehow managed to avoid 3 leaf assemblies in my projects.
Old 19th June 2020
  #45
Quote:
Originally Posted by Kyle P. Gushue View Post
Fair enough. Im enjoying following this thread.

Id had to double check but i believe the rule if thumb for fresh air return is 15 cfm per person. So you estimate occupancy of the room and multiply the number of people x 15cfm.

Not sure if that's exactly what your asking.
I guess so. I thought it would be more complicated than that. lol.
Old 19th June 2020
  #46
Lives for gear
 
Kyle P. Gushue's Avatar
Quote:
Originally Posted by Jag94 View Post
I guess so. I thought it would be more complicated than that. lol.
Lol.
Old 20th June 2020
  #47
Quote:
Originally Posted by Kyle P. Gushue View Post

Imho its worth knowing the cost of both before deciding. And worth a call to someone to calculate it for me.
Yeah I called a couple of places to get some estimates.

I actually think it might not be that bad. The plywood sheathing that is there now can stay, I think. Then it's just a moisture barrier, the thick foam insulation, and then shingles. I'll have to see what they say when they come by next week.
Old 20th July 2020
  #48
Is there a recourse for learning how to build a frame? I understand the concepts and know how to build a single wall, how to cut rafters, frame a door, and some other basic aspects, but I'm looking for a more in depth tutorial. Something that will cover everything, putting it all together. That would include proper connectors, how to frame a gable end wall, how to make sure the frame is strong enough for the mass I want to put on it, etc. I've been google searching and watching a lot of youtube videos, but since it's a single room, I'm getting a lot of "how to build a shed" or "how to build a shed roof" kind of stuff. I'm looking for a more comprehensive recourse. Any books anyone can recommend?
Old 20th July 2020
  #49
Lives for gear
 
Kyle P. Gushue's Avatar
"This Old House" is a long running program on public broadcasting. Over 30+ years they've covered just about everything by now, and they do it "right".

I would search around their content. Other than that i don't have any books to reccomend off hand.
Old 27th July 2020
  #50
Ok so after a bit more research, and re-reading Rod's book, I feel like I have a LITTLE better understanding of the HVAC situation. HVAC is complicated. Here's what I have so far.

Like i stated earlier, the area of the inner completed room will be roughly 1900 cubic feet (15x14x8.5).

I will be using THIS HRV unit.

It has 3 modes, 35cfm, 50cfm, and 71cfm.

I have been reading and re-reading THIS POST by Gregwor over at John Sayers site. (6th post down with the Duct charts).

I'm trying to figure out how big I need to build my baffle boxes, but I am extremely confused by the charts and math that Gregwor put in that post. Also, does it matter that the HRV unit can change the CFM? Should i just build the box for the highest CFM rating, or is it more complicated than that?

I will be putting the two baffle boxes inside the room. I am aware that they can be quite huge, but that's OK. It's my only option, and well, that's how it goes. I plan on making them pretty beefy too, 3/4" OSB, and 2 layers of drywall (same as my inner walls).

The ducts will travel in the south wall, and either penetrate the south exterior leaf, or the west exterior leaf. Does the duct length matter?

Any help with figuring this out would be greatly appreciated.
Old 27th July 2020
  #51
Lives for gear
 
Kyle P. Gushue's Avatar
Quote:
Originally Posted by Jag94 View Post
Ok so after a bit more research, and re-reading Rod's book, I feel like I have a LITTLE better understanding of the HVAC situation. HVAC is complicated. Here's what I have so far.

Like i stated earlier, the area of the inner completed room will be roughly 1900 cubic feet (15x14x8.5).

I will be using THIS HRV unit.

It has 3 modes, 35cfm, 50cfm, and 71cfm.

I have been reading and re-reading THIS POST by Gregwor over at John Sayers site. (6th post down with the Duct charts).

I'm trying to figure out how big I need to build my baffle boxes, but I am extremely confused by the charts and math that Gregwor put in that post. Also, does it matter that the HRV unit can change the CFM? Should i just build the box for the highest CFM rating, or is it more complicated than that?

I will be putting the two baffle boxes inside the room. I am aware that they can be quite huge, but that's OK. It's my only option, and well, that's how it goes. I plan on making them pretty beefy too, 3/4" OSB, and 2 layers of drywall (same as my inner walls).

The ducts will travel in the south wall, and either penetrate the south exterior leaf, or the west exterior leaf. Does the duct length matter?

Any help with figuring this out would be greatly appreciated.
Hvac is a weak area for me, hopefully a pro chimes in, or id call one.

I do know the longer the duct the more loss incurred. Wheather this matters for air exchange i don't know. There is also a performance difference with regard to solid vs flex duct.

Sorry i can't help more here.

I would *presume* you design the box to the maximum spec.
Old 29th July 2020
  #52
Quote:
Originally Posted by Kyle P. Gushue View Post
Hvac is a weak area for me, hopefully a pro chimes in, or id call one.

I do know the longer the duct the more loss incurred. Wheather this matters for air exchange i don't know. There is also a performance difference with regard to solid vs flex duct.

Sorry i can't help more here.

I would *presume* you design the box to the maximum spec.
As always, Kyle, thank you for responding.

When you say performance difference between solid and flex duct, do you mean air flow performance, or sound isolation performance?
Old 29th July 2020
  #53
Lives for gear
 
Kyle P. Gushue's Avatar
Quote:
Originally Posted by Jag94 View Post
As always, Kyle, thank you for responding.

When you say performance difference between solid and flex duct, do you mean air flow performance, or sound isolation performance?
I was referring to airflow / energy efficiency. Im not sure how relavant it is for an hrv, but is definitely relavant in heating/cooling.

Rod reccomends solid insulated ducts for hvac, ive never seen a reccomendation from him on hrv ducting. He told me to just locate the hrv supply above or below the mini split blower to treat the air Immediately avoiding drafts.

Ive seen Northward talk about flex ducting between adjacent rooms, in a thread here.

I appologize for the non-answers. Hvac design doesn't seem to get covered alot on threads, despite its importantance. Im planning on hiring Rod for help with hvac and electrical when i build my personal studio.
Old 9th August 2020
  #54
Ok so after a bit more research, and re-reading Rod's book, I feel like I have a LITTLE better understanding of the HVAC situation. HVAC is complicated. Here's what I have so far.

Estimated dimensions of finished interior room:
15' 3" x 14' 3" x 8' 6"
approx 1800 cubic feet.

With an ideal 6 room changes per hour, that's approx 10.700 cubic feet per hour. Most everything is categorized in cubic feet per minute (not hour), so divide that number by 60, and you get...

10,700/60 = ~178 CFM

The Ductless Mini-Split I will be using has these specs:
High speed - 294 CFM
Medium speed - 212 CFM
Low Speed - 147 CFM

So the split system will be able to heat/cool the room adequately.

To make sure I'm getting enough fresh air into the room, I need 1/4 to 1/2 of the room circulation rate. 40% is a good number to use to estimate.

So 178 x 40% = ~71 CFM

The HRV I want to use has these specs:
High speed - 71 CFM
Medium speed - 53 CFM
Low speed - 35 CFM.

So far we are looking good.

Here's the situation I'm in. I will be using this HRV unit.

HRV UNIT

This unit is designed to be installed INSIDE the room. The incoming air and exhaust vents are on the unit itself. It has two 5" ducts on the back that are supposed to go straight through the wall (using duct extenders) and brought straight outside. Obviously this will not work for sound isolation.

As mentioned in a post earlier... I will be putting the two baffle boxes inside the room. I am aware that they can be quite huge, but that's OK. It's my only option, and well, that's how it goes. I plan on making them pretty beefy too, 3/4" OSB, and 2 layers of drywall (same as my inner walls).

I have 3 goals.

1) Make sure I'm getting fresh air in the room, and stale air is being brought out.
2) Make sure the air is conditioned properly.
3) make sure my drumming does not get out of the building through the ducts.

I DO NOT care about the HRV/Mini-Split system noises inside the room. I learned that a lot of the baffle box design and use is to ALSO eliminate the sound of the HVAC units themselves from getting to the room. 80% of the time it is just going to be me in the room practicing. 15% will be me recording, 5% will be full band rehearsals. When I'm practicing by myself, or having full band rehearsals, the sound of the units do not matter at all. The sound not getting out is priority number 1, and getting fresh air inside the room is priority number 2. When I am recording, it is most likely going to be just me, so if I need to turn down or turn off the systems to eliminate the noise for 5-10 minutes at a time, I'm perfectly fine doing this. And in all likelihood, the noise won't be enough to bother me during recording anyway.

Here is a sketchup of my idea. It is a VERY rough sketch, but just enough to give you an idea. The HRV will be on the wall to the left of the mini-split. The fresh air vent on the HRV is on the right side, so that air will hit the mini-split immediately after leaving the vent. Both ducts will go down and enter the baffle boxes. The boxes will hit the south wall and the air will be brought outside via ducts inside the south wall.

https://imgur.com/a/Zp6tLe9

I just need help figuring out how big these silencer boxes need to be, and how big of ducts I need to use inside the wall. Or if I even need the traditional baffle box. Perhaps just flex duct inside a "tube" that has the same material make-up of the wall, then the flex duct just exits out the exterior leaf.
Old 9th August 2020
  #55
Gear Nut
 

About roofs...

Look up "hot roof," especially the greenbuildingdesigner.com articles. If you do it right, you can build a perfectly good roof without venting. It may cost a little more, depending on what and how much you insulate, but not an arm and a leg.

I am not 100% sure, but a rigid foam cut and cobble or an encapsulated spray foam may be sufficient for the roof to act like one big leaf, then your interior ceiling system is the second.

Jon
Old 9th August 2020
  #56
Lives for gear
 
Kyle P. Gushue's Avatar
Quote:
Originally Posted by Jag94 View Post
Ok so after a bit more research, and re-reading Rod's book, I feel like I have a LITTLE better understanding of the HVAC situation. HVAC is complicated. Here's what I have so far.

Estimated dimensions of finished interior room:
15' 3" x 14' 3" x 8' 6"
approx 1800 cubic feet.

With an ideal 6 room changes per hour, that's approx 10.700 cubic feet per hour. Most everything is categorized in cubic feet per minute (not hour), so divide that number by 60, and you get...

10,700/60 = ~178 CFM

The Ductless Mini-Split I will be using has these specs:
High speed - 294 CFM
Medium speed - 212 CFM
Low Speed - 147 CFM

So the split system will be able to heat/cool the room adequately.

To make sure I'm getting enough fresh air into the room, I need 1/4 to 1/2 of the room circulation rate. 40% is a good number to use to estimate.

So 178 x 40% = ~71 CFM

The HRV I want to use has these specs:
High speed - 71 CFM
Medium speed - 53 CFM
Low speed - 35 CFM.

So far we are looking good.

Here's the situation I'm in. I will be using this HRV unit.

HRV UNIT

This unit is designed to be installed INSIDE the room. The incoming air and exhaust vents are on the unit itself. It has two 5" ducts on the back that are supposed to go straight through the wall (using duct extenders) and brought straight outside. Obviously this will not work for sound isolation.

As mentioned in a post earlier... I will be putting the two baffle boxes inside the room. I am aware that they can be quite huge, but that's OK. It's my only option, and well, that's how it goes. I plan on making them pretty beefy too, 3/4" OSB, and 2 layers of drywall (same as my inner walls).

I have 3 goals.

1) Make sure I'm getting fresh air in the room, and stale air is being brought out.
2) Make sure the air is conditioned properly.
3) make sure my drumming does not get out of the building through the ducts.

I DO NOT care about the HRV/Mini-Split system noises inside the room. I learned that a lot of the baffle box design and use is to ALSO eliminate the sound of the HVAC units themselves from getting to the room. 80% of the time it is just going to be me in the room practicing. 15% will be me recording, 5% will be full band rehearsals. When I'm practicing by myself, or having full band rehearsals, the sound of the units do not matter at all. The sound not getting out is priority number 1, and getting fresh air inside the room is priority number 2. When I am recording, it is most likely going to be just me, so if I need to turn down or turn off the systems to eliminate the noise for 5-10 minutes at a time, I'm perfectly fine doing this. And in all likelihood, the noise won't be enough to bother me during recording anyway.

Here is a sketchup of my idea. It is a VERY rough sketch, but just enough to give you an idea. The HRV will be on the wall to the left of the mini-split. The fresh air vent on the HRV is on the right side, so that air will hit the mini-split immediately after leaving the vent. Both ducts will go down and enter the baffle boxes. The boxes will hit the south wall and the air will be brought outside via ducts inside the south wall.

https://imgur.com/a/Zp6tLe9

I just need help figuring out how big these silencer boxes need to be, and how big of ducts I need to use inside the wall. Or if I even need the traditional baffle box. Perhaps just flex duct inside a "tube" that has the same material make-up of the wall, then the flex duct just exits out the exterior leaf.
It might be worth considering some isolation mounts for the hrv unit to mitigate vibrations from the unit, transferring to the wall.

As far as ducting and baffle boxes go, i am not sure.

This post from northward, or the thread in general might help you.

Howโ€™s these HVAC baffles look?
Old 10th August 2020
  #57
Quote:
Originally Posted by Jon Best View Post
About roofs...

Look up "hot roof," especially the greenbuildingdesigner.com articles. If you do it right, you can build a perfectly good roof without venting. It may cost a little more, depending on what and how much you insulate, but not an arm and a leg.

I am not 100% sure, but a rigid foam cut and cobble or an encapsulated spray foam may be sufficient for the roof to act like one big leaf, then your interior ceiling system is the second.

Jon
Hi Jon,

Thanks. I am actually having a hot roof installed this week. It is expensive, but they will get it done in a day, and I won't spend a week venting the roof and creating a 3 leaf roof.


Quote:
Originally Posted by Kyle P. Gushue View Post
It might be worth considering some isolation mounts for the hrv unit to mitigate vibrations from the unit, transferring to the wall.

As far as ducting and baffle boxes go, i am not sure.

This post from northward, or the thread in general might help you.

Howโ€™s these HVAC baffles look?

I plan on building a housing for the unit itself so it is not touching the wall, for the exact reason you stated.

Yeah I've read that thread many times. Unfortunately it's difficult for me to use that information and make it work for my situation. I'd really hate to try something and it kills the isolation I've spent so much time and money building.
๐Ÿ“ Reply

Similar Threads

Thread / Thread Starter Replies / Views Last Post
replies: 4353 views: 450321
Avatar for Elsongs
Elsongs 7th September 2017
replies: 33 views: 4794
Avatar for Hexachords
Hexachords 1 week ago
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
๐Ÿ–จ๏ธ Show Printable Version
โœ‰๏ธ Email this Page
๐Ÿ” Search thread
๐ŸŽ™๏ธ View mentioned gear
Forum Jump
Forum Jump