Soundman2020 - Studio Design Forum

DISCLAIMER: some of the pictures have imported sideways. I apologize for this, but I don't know how to fix it. Just turn your head to the right to get a better look.

I started a thread in the design section of this forum to ask about a specific HVAC design, but I think it makes more sense to start a complete progress thread to be more clear, and keep everything in one place. Below is yet another garage conversion story.

The Plan:
My wife and I bought our first house (finally), and I am excited to finally be able to build a rehearsal/recording studio in the garage. My goal is to convert the garage to a rehearsal space that contain my drums. I am doing a full "room in a room" design. I am in 4 bands at the moment, so I have a lot of practicing to do, and it'd be nice to be able to practice without worrying about my neighbors hating me. I have been known to practice for 8-10 hours a day, so simply asking my neighbors to tolerate the noise is not fair to them. Being able to track drums in there is a close 2nd in terms of priority. I will also likely be having full band rehearsals a couple of times a month.

I'd say:
80% of the time it's just me in the room practicing.
10% of the time I'll be tracking drums
10% of the time I'll have full band rehearsals.

I figure it will take me a year to complete the project, including research, planning, design, construction, and room treatment. I have been researching and planning for about 5-6 months already, and have started construction 3 about months ago. I am doing the majority of the work myself, so it has been extremely slow going, but that was to be expected. I am working with a structural engineer because of the roof issues i'll explain later in the post, and I will be consulting with an electrician when it comes time to do the electrical (my plans for that will be detailed below as well). I may hire a contractor to help with things I'm concerned about, but I'm really trying to keep this as DIY as possible to keep the costs down.

Budget:
I originally thought I could do this for $10,000, but after doing some initial research and material sourcing, I was looking at a materials cost of around $20,000+. Then I started to learn more about what REALLY works in sound isolation (thanks to forums like this, and Rod's book). I learned that using the right materials IN THE RIGHT PLACE makes more of a difference than MORE materials, or expensive materials that are marketed as "sound proofing" materials. I am now working with a materials budget of $15,000 and so far that's looking pretty good. I'm keeping track of every penny spent, and so far I'm on schedule. I am not including room treatment in this budget, just isolation materials. I will re-evaluate budget when I get ready to treat the room.

Isolation Needs
I had a friend walk around the property with a spl meter while I played at full volume on the drums. I had him take measurements at key points around the property. My biggest concern is my neighbor to the west. His house is about 30 feet from my garage, and i was getting levels of about 81dbC on that side of the garage, and 93dbC in front of the garage where his house is closest to. I am aware that with my budget and construction methods, the absolute MAXIMUM I could achieve would be about 70db of TL... and that's if everything is done perfectly with no mistakes. Realistically I know to expect probably 50db of TL, and if I got that, I'd be OK with it. My budget isn't very big, so planning and making sure I do this right the first time is a priority.

Garage Specs
The garage is on the smaller side. It was built in 1936. It is unfinished which is nice because that's less work to take down any drywall or plywood on the interior and I can get right to beefing up the exterior leaf. The exterior is stucco (approx 1 inch thick), and the roof is 7/16" OSB roof sheathing with roof shingles on top. The studs and rafters are 2x4 (1 7/8 x 3 5/8), and the garage door is metal.

The inside measures from stud face to stud face
17' 7 1/2" x 15' 4" x 8' 1" high (to the top of the top plate).

The peak of the roof is 11' 4", and is a 4/12 roof pitch. There is a ridge board (not ridge beam) that measures 5 1/2" by 3/4".

The floor is concrete slab on grade, and in fantastic condition considering how old it is. I took a 4ft level and placed it all over the floor in every possible direction, and it's level with no dips or bumps. there are some small hair line fractures, and a some very small chips here and there, but nothing to be concerned with.

Here is a sketchup of the exterior frame.


There were 2 horizontal rafter ties, and 2 diagonal rafter ties.


One of the reasons I hired a structural engineer, was I wanted to remove these rafter ties so that I could raise the ceiling of the inner "room" as high as I could. So I needed help with making sure the walls wouldn't lean and the roof collapse. Apparently that's not good.

I have removed those ties, and have installed massive gussets with new 2x6 rafter ties higher up on the rafters to raise the effective ceiling height of the finished room. I didn't end up with as much ceiling height as I originally wanted, but I definitely got more than I would have.

Design Plan for Garage:

I will be building a single room, no booths, no separate mixing station. I do most of my recording by myself, so I don't need a separate space for that.

Exterior wall will look like this:
Stucco > 3/4" OSB > 5/8" drywall (backer rod and caulked around all drywall pieces)
pink fluffy inside stud bays as well as cavity

Interior Frame (walls and ceiling):
2x6 frame stuffed with pink fluffy
3/4" OSB > Green Glue > 5/8" Drywall > Green Glue > 5/8" Drywall
The perimeter of all drywall will be spaced 1/4", and 3/8" backer rod will be stuffed around and caulked. I will be using the staggered drywall installation method I have seen in Rod's book and all over this forum. Ceiling first, North/South walls 2nd, East/West walls 3rd, allowing space for backer rod and caulk around the perimeter.

First step is to beef up the existing outer leaf. This took the most amount of time. It was extremely tedious to cut the OSB and drywall into the proper sizes and shapes because of the diagonal bracing of the existing frame. Cutting the cleats to those exact angles was a pain in the ass, but it looks great, and feels super solid.

- I have already installed strips of 3/4" OSB into the stud bays, and secured them in place with wood cleats. I have caulked the edges.




(sideways)


(sideways)

Next up was cutting the drywall and fitting it into place. Again, very tedious, but I'm happy with the way it turned out. I left a gap of about 3/8" around the drywall pieces at first, then stuffed it with 1/2" backer rod and caulked. I have decided that 3/8" is too big, because there were a lot of uneven studs and it caused much bigger gaps. So after the first 6 bays, I switched to 1/4" gaps and 3/8" backer rod, using 1/2" in areas that had slightly larger gaps... and this was MUCH better.


(sideways)

The under side of the roof has slats from north to south just above the rafters. The sheathing is then nailed to these slats. This made things slightly more complicated in that if I was to add layers of mass directly under the slats, there would be hundreds of 1" air gaps between the added mass, and the OSB roof sheathing.


(sideways)

So I added 1" EPS foam in between each slat. Again, INSANELY tedious because no two gaps were the same size, but it allowed me to add a layer of mass directly to the underside of the roof sheathing with no gaps, making sure the outer leaf was one continuous leaf.


(sideways)

Next up was building and installing the massive gussets. The reason they are so big, is not only to stop the walls from pushing out (and causing the roof to collapse), but also to support the added weight of all the mass I was installing for the "beef up". The structural engineer I was working with was very difficult, as it seemed he had never done anything like this before, so it was a real struggle to get him to understand what I was doing. In the end, I'm OK with how it turned out. here is the design we ended up with, after weeks of back and forth emails and design tweaking. I had to special order these "skewed angle brackets" from Simpson Strong Tie, and use massive 5/8" thru bolts to secure install it all together.






Finally, here is the result of them installed.


(sideways)




(sideways)

At this point, all 3 walls, including the gable end above the garage door and the ceiling are "beefed up". I am sealing up the garage door as we speak. next up is building the interior frame.



I found a new structural engineer who gave me some tips on making a solid interior frame. I did the design, he just tweaked it and made sure I was adding the right supports in the right places. He was a PLEASURE to work with, and I wish I had found him in the beginning. I would have saved thousands of dollars. But we live and learn.

I'll post my progress on the frame build as it happens (hopefully in the next week or so). I will be flying to Tahiti and Bora Bora for a much needed vacation with my wife in a few weeks, so having the frame done before I leave would be lovely.

Electircal:
To achieve maximum isolation, I plan on having the sub panel, and all outlets face mounted onto the drywall so there is just 1 hole in the wall where the power is being brought into the room. I will be using metal conduit and metal boxes so I can run a STAR grounding system with isolated receptacles for all studio/music gear. There is currently a 40 amp sub panel, but I am going upgrade that to a 60 amp sub panel. I will have more questions about this when I get closer, but I have a good foundation of how this will go.

HVAC
As I get closer to building the interior frame, it is becoming increasingly imperative that I figure out the HVAC for the room. I posted a lot of this in the other thread, so bare with me if you've already read it.

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 approximately 10,700 cubic feet per hour. Most everything is categorized in cubic feet per MINUTE (not hour), so divide 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, right? 40% is a good number to use to estimate.

So 178 x 40% = ~71 CFM

The HRV unit I have been looking at has these specs:
High speed - 71 CFM
Medium speed - 53 CFM
Low speed - 35 CFM.

So I think that unit will provide the air circulation that I need.

Here's the situation I'm in. THIS HRV UNIT is designed to 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.

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. Like I stated earlier, 80% of the time it is just going to be me in the room practicing and about 10% tracking drums. 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.



I need help with building the right size silencer boxes, and figuring out how big my ducts need to be inside the wall carrying the air to/from the outsize via the exterior leaf. The longer the duct run, the less efficient the HRV unit will operate.

I have not purchased the HRV unit yet, so if I need to go another route I will. Also, I can NOT put any HRV or ERV outside of the room. There is simply no place for me to put it. I am out of space, lol.

If any of you are still alive after reading this, I commend you. And also, I'm sorry. haha. But if you have any advice, please, I'm all ears!

DISCLAIMER: some of the pictures have imported sideways. I apologize for this, but I don't know how to fix it. Just turn your head to the right to get a better look

Don't worry: It isn't you! It's a bug in the forum software, that I haven't been able to track down yet. When you post a picture that is too big to fit comfortably within a post, then it is supposed to make a smaller version of that image to go in the post, while still keeping the full-size version, that you can access by clicking on the smaller version. But for some reason, it sometimes decides that it also need to rotate the small version! Instead of just re-sizing it. And it only does that with some image types, not others... Hard to figure out! It is also doing the opposite: for images that are a lot smaller than the width of a post, it has now decided that it should make them BIGGER, to fill the width... but it is not supposed to do that either! Sigh! I'll figure it out one day when I have time. Sorry about that! The forum software is great, but rather complex to configure in some aspects...

but I think it makes more sense to start a complete progress thread to be more clear, and keep everything in one place. Below is yet another garage conversion story.

Fantastic!

I have been known to practice for 8-10 hours a day, ... Being able to track drums in there is a close 2nd in terms of priority. I will also likely be having full band rehearsals....

So, clearly, high isolation is the number one goal for your studio. You mentioned a goal of around 50 dB TL, and that is completely achievable. Have you checked on the legal "noise regulation" requirements in your area? Sometimes those are just absurd, but it's good to know what they say.

I figure it will take me a year to complete the project, including research, planning, design, construction, and room treatment. I have been researching and planning for about 5-6 months already,

That's realistic, and achievable. Excellent. Too often I hear from people who want to build Abbey Road in their back yard, starting tomorrow, and wanting it done by next Tuesday... OK, I exaggerate just a little, but a lot of people have unrealistic goals and planning estimates. Yours is in the ballpark!

am working with a structural engineer

Very smart! And VERY important. Once again, many first-time home-studio builders don't do that, and think they can save money like that, figuring it all out themselves... but it is VERY necessary! For many reasons, but a few basic ones come to mind: 1) It would be sad if someone spent a lot of time and money building a studio, but then it collapsed on them, killing them or injuring them severely, so they can no longer make music... 2) If you modify your home in any way, structurally, without the right approvals and permits, then you have very likely invalidated your home owner's insurance policy. If something does go wrong, your insurance company will laugh at you when you try to file a claim, and it will all be on your head. You will be responsible not just for the cost of repairing the damage, but also for the hospital (funeral?) costs of anyone who was injured. That responsibility is both civil and criminal.... So it is well worthwhile doing what you did: get a structural engineer to sign off on everything! And of course, also get all the permits and inspections required by aw in your area. Smart move!

I originally thought I could do this for $10,000, but after doing some initial research and material sourcing, I was looking at a materials cost of around $20,000+.

Yup! That is, indeed, the way it often goes with home studios. The real costs can balloon far beyond what the original budget was. Pretty much always, the initial "budget" is just a fantasy, very far from reality.

Then I started to learn more about what REALLY works in sound isolation (thanks to forums like this, and Rod's book). I learned that using the right materials IN THE RIGHT PLACE makes more of a difference than MORE materials, or expensive materials that are marketed as "sound proofing" materials.

So true! That's one of those things that really upsets me: vendors of "soundproofing" supplies that try to sell you stuff that costs way more than standard building materials, but with little to no acoustic benefit. As you already found, the best plan is to use the least expensive material that will do the job, and use it intelligently: correctly positioned for maximum effect, and correctly installed.

Realistically I know to expect probably 50db of TL, and if I got that, I'd be OK with it. My budget isn't very big, so planning and making sure I do this right the first time is a priority.

If you work very carefully, then you could probably get 55, with a bit of luck.

The exterior is stucco (approx 1 inch thick),

That's a good start! Plenty of mass in that already.

17' 7 1/2" x 15' 4" x 8' 1" high (to the top of the top plate).

so, about 270 ft2, roughly. That's a decent size.

The floor is concrete slab on grade, and in fantastic condition considering how old it is.

Excellent! And that's actually a good thing about old construction: they built things tough back then.

One of the reasons I hired a structural engineer, was I wanted to remove these rafter ties so that I could raise the ceiling of the inner "room" as high as I could.

Another smart move. Extra ceiling height is always good in a studio, and even more so for a live room/rehearsal room (as opposed to a control room, where it is still important, but not quite so critical).

Exterior wall will look like this:
Stucco > 3/4" OSB > 5/8" drywall (backer rod and caulked around all drywall pieces)
pink fluffy inside stud bays as well as cavity

Interior Frame (walls and ceiling):
2x6 frame stuffed with pink fluffy
3/4" OSB > Green Glue > 5/8" Drywall > Green Glue > 5/8" Drywall

That's why I said you should be able to get 55 dB TL. That's a good plan, with plenty of mass, and GG. Better-than-average isolation is in your future....

- I have already installed strips of 3/4" OSB into the stud bays, and secured them in place with wood cleats. I have caulked the edges.

Wow! Nice work! Excellent attention to detail! This bodes well for the 55 dB...

One thing you could consider, is that the cleats don't really need to cover 100% of the edge. It's fine to just have backer rod and caulk in there, with some cleats to hold the sheets firmly in place. That's the real purpose: to provide support for the sheathing panels. The backer rod and caulk takes care of the seal and mass in the gaps. There's nothing wrong with what you did! It's great! But it's a bit more than you need. You could have cut the cleats a bit short in those nasty corners, for example, to make your job easier. But it does look really good, and the isolation is going to be really good too.

Next up was building and installing the massive gussets. The reason they are so big, is not only to stop the walls from pushing out (and causing the roof to collapse), but also to support the added weight of all the mass I was installing for the "beef up". The structural engineer I was working with was very difficult, as it seemed he had never done anything like this before, so it was a real struggle to get him to understand what I was doing.

Story of my life! I feel for you... dealing with architects, contractors, and structural engineers who have never done studios before, is ... ummm.. shall we say "interesting"!

In the end, I'm OK with how it turned out. here is the design we ended up with, after weeks of back and forth emails and design tweaking. I had to special order these "skewed angle brackets" from Simpson Strong Tie, and use massive 5/8" thru bolts to secure install it all together.

Unusual, but it certainly looks like they should do the job.

I do like the ply gussets: those are excellent. You certainly have plenty of structure up there, to do the job, from what I can see.

I am sealing up the garage door as we speak.

Great! What's your plan for that?

The HRV unit I have been looking at has these specs:
High speed - 71 CFM
Medium speed - 53 CFM
Low speed - 35 CFM.

So I think that unit will provide the air circulation that I need.

That should work out fine.

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.

Have you considered putting them up in the ceiling space, between your inner-leaf ceiling and outer-leaf roof, in the peaked central part? There's a lot of room up there, that could be put to good use. The problem then becomes: where to put the HRV itself? Hmmmm....

Another thought: when you isolate your garage door, I'm assuming you will be putting up an isolation wall behind the existing door. If so, then you could potentially put the HRV inside that area, and make it accessible from the outside, just by opening the garage door...

I need help with building the right size silencer boxes, and figuring out how big my ducts need to be inside the wall carrying the air to/from the outsize via the exterior leaf. The longer the duct run, the less efficient the HRV unit will operate.

I'm sure you are already aware of this, but the basic idea is to get the outlet from the HRV as close as possible to the inlet into the mini-split, so that incoming fresh air goes directly into the mini-split, to be conditioned before it gets into the room proper. But the return into the HRV should also be as far away as possible from the mini-split, so that it isn't just sucking the conditioned air right back out again. That's not an easy problem to solve! What is the maximum duct length allowed, according to the manufacturer of the HRV? Worst case, you can always add a booster fan in-line with a duct somewhere... but balancing the airflow between that fan and the HRV's own fan isn't so easy.


- Stuart -

Don't worry: It isn't you! It's a bug in the forum software, that I haven't been able to track down yet. When you post a picture that is too big to fit comfortably within a post, then it is supposed to make a smaller version of that image to go in the post, while still keeping the full-size version, that you can access by clicking on the smaller version. But for some reason, it sometimes decides that it also need to rotate the small version! Instead of just re-sizing it. And it only does that with some image types, not others... Hard to figure out! It is also doing the opposite: for images that are a lot smaller than the width of a post, it has now decided that it should make them BIGGER, to fill the width... but it is not supposed to do that either! Sigh! I'll figure it out one day when I have time. Sorry about that! The forum software is great, but rather complex to configure in some aspects...

Dude, the forum is great. Not only do you moderate it well, but everyone here is extremely polite and helpful. You have created a great resource for people like us. that small glitch is a non issue.

So, clearly, high isolation is the number one goal for your studio. You mentioned a goal of around 50 dB TL, and that is completely achievable. Have you checked on the legal "noise regulation" requirements in your area? Sometimes those are just absurd, but it's good to know what they say.

I have looked at the noise requirements for my area, and I won't have any issues even if I do a lousy* job.

Exterior wall will look like this:
Stucco > 3/4" OSB > 5/8" drywall (backer rod and caulked around all drywall pieces)
pink fluffy inside stud bays as well as cavity

Interior Frame (walls and ceiling):
2x6 frame stuffed with pink fluffy
3/4" OSB > Green Glue > 5/8" Drywall > Green Glue > 5/8" Drywall

That's why I said you should be able to get 55 dB TL. That's a good plan, with plenty of mass, and GG. Better-than-average isolation is in your future....

One thing I forgot to mention, I planned on having a 1" space between the exterior frame and the interior frame. With the beef-up in the exterior frame, 1" air gap, and 5 1/2" for the 2x6 interior frame, that gives me about 8 1/4" as an air gap. I have been thinking about adding an additional inch between the frames to give me 9 1/4" air gap... but I'm wondering if it will be worth it. Will I gain a proportional amount of isolation as I will lose in overall square footage of the room? Or am I good with the 8 1/4" air gap?

One thing you could consider, is that the cleats don't really need to cover 100% of the edge. It's fine to just have backer rod and caulk in there, with some cleats to hold the sheets firmly in place. That's the real purpose: to provide support for the sheathing panels. The backer rod and caulk takes care of the seal and mass in the gaps. There's nothing wrong with what you did! It's great! But it's a bit more than you need. You could have cut the cleats a bit short in those nasty corners, for example, to make your job easier. But it does look really good, and the isolation is going to be really good too.

I thought about this. And I'm actually happy that I didn't see your response about this until after it was already done (lol). The stucco was quite un-even on the inside. So there was a lot of "wiggle" when pushing the OSB against the back of the stucco. If I had not cut the cleats to cover the entire area, there may have been areas where there were gaps between the OSB and stucco of 1/2". By making the cleats full length, I was able to push the OSB as close as possible to the back of the stucco. There are for sure spots on the walls where there is still a gap. It's not perfect, but I'm happy with the result.

I am sealing up the garage door as we speak.

Great! What's your plan for that?

Well... I'm not sure I want to answer this. lol. I posted about this on gearslutz, and you gave me your opinion, and it strongly disagreed with another users opinion. I have decided to use the other persons idea. But there is a very specific reason why.

What I've done is completely sealed the garage door into place. Once I removed the spring and rails, I caulked the entire perimeter, then screwed the door in place on all sides. Then I caulked it again. Maybe I was a bit overkill on the caulk, but I figured it couldn't hurt. Then I went outside, and caulked the door from the outside on all 4 sides. I also caulked in between each door panel (I closed the door one panel at a time and caulked in between) then caulked again once it was completely closed.

I will be putting EPS foam into the inside panels of the door on the inside so that when I build and stand up the isolation wall that will go up against the garage door, it will create a single complete outer leaf. I saw the idea on john sayers studio design site, and I feel that it will work very well for my design.

I'll post more pictures as I do it. I accidentally broke one of the windows on the garage door, so I need to repair that before I do anything (which I'm pretty pissed about). I also purchased THIS noise dampening paint to paint onto the door to reduce vibrations.

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.

Have you considered putting them up in the ceiling space, between your inner-leaf ceiling and outer-leaf roof, in the peaked central part? There's a lot of room up there, that could be put to good use. The problem then becomes: where to put the HRV itself? Hmmmm....

The interior wall on the north side (where the garage door is) will have a VERY large gap between the interior/exterior walls. I figure the gap between these is large enough that any silencer boxes and ducts should be in that space.

Another thought: when you isolate your garage door, I'm assuming you will be putting up an isolation wall behind the existing door. If so, then you could potentially put the HRV inside that area, and make it accessible from the outside, just by opening the garage door...

The door is a roll up style door (or at least it was before I removed all the tracks, springs and rails). Once the door closed, it can no longer be opened.

I need help with building the right size silencer boxes, and figuring out how big my ducts need to be inside the wall carrying the air to/from the outsize via the exterior leaf. The longer the duct run, the less efficient the HRV unit will operate.

I'm sure you are already aware of this, but the basic idea is to get the outlet from the HRV as close as possible to the inlet into the mini-split, so that incoming fresh air goes directly into the mini-split, to be conditioned before it gets into the room proper. But the return into the HRV should also be as far away as possible from the mini-split, so that it isn't just sucking the conditioned air right back out again. That's not an easy problem to solve! What is the maximum duct length allowed, according to the manufacturer of the HRV? Worst case, you can always add a booster fan in-line with a duct somewhere... but balancing the airflow between that fan and the HRV's own fan isn't so easy.

The problem with the HRV that I want to use, is that the outlet and return for the HRV are on the unit itself. So even if I position it so that the outlet blows directly into the mini-split, the return is approximately 20 inches away on the other side of the unit.

I am not dead set on the HRV system. If i need to just put a fan in the wall to pull stale air out, and put a hole in the wall on the other side of the studio so that fresh air comes in, that's fine. I just want to make sure I'm getting a good exchange of air. My biggest obstacle, is whatever system I use, everything needs to be accessible from the inside so I can service it if necessary. So silencer boxes, HRV (or fan units), need to be accessible from the inside of the room.

Update on recent progress.

I sealed the sill plate (bottom plate) on the exterior frame. I used DAP 230 caulk, and then put Wigluv seal tape over it. There will be absolutely zero air, water, bugs, sound getting through the exterior frame.





I also taped off around the inside of the garage door to prepare for the "Second Skin" sound deadening paint. This stuff is meant to be used on cars to deaden the reverberation inside the car, but can be used on anything metal. I'm excited to see how it will perform on the metal garage door. This is the stuff. https://www.secondskinaudio.com/sound-d ... rum-liquid

Ready to paint!



Next up will be an added mass wall to attach to the garage door to make one solid exterior leaf. Then building the interior frame.

Greetings,

If i need to just put a fan in the wall to pull stale air out, and put a hole in the wall on the other side of the studio so that fresh air comes in, that's fine. I just want to make sure I'm getting a good exchange of air.

You probably have already thought of this, but just in case: You will need filtration for the outside air to keep your gear (and you) in good shape. A simple fan system does not provide that, and dust/smog/etc could be a major problem.

All the best,

Paul

Yeah I figured I'd have to put some sort of filtration in the line somewhere. I really would rather have the HRV unit and not worry about it, but I just first need to figure out where to put the damn thing. lol.

In your other topic, Jag94, Paul and Stuart were recommending that you place it centrally on the front wall of your studio, where it can be boxed in. Based on your drawing, above, that would mean relocating the AC, although that could also be centred but above and in front of the HRV. It would be in front of the HRV because the HRV would be inside the building but behind the speaker soffit wall (as per Stuart's photo) and the AC would be in the studio. As your HRV, according to the PDF you linked to in your other topic, has two vents, at the bottom of borth sides. If you can add a short duct so that the fresh air goes up and blows into the AC's air intake, and a long duct so that the extraction vent effectively reaches to the rear of your studio. That may need an inline fan if your HRV is not up to the job without help.

Look again at what Stuart wrote and the photos he posted in your other topic, especially around this one:


PS. You don't need to add additional filters; your HRV has filters on both incoming and extrated air.

Hey Starlight,

Thanks for chiming in. I'm not sure building an enclosure for the HRV unit is necessary. I'm not so much worried about the noise of the unit. I'm more worried about the sound/drumming/music inside the studio getting through the isolation and going outside. I also was not planning on building speaker soffits. This room is more of a live room/practice & rehearsal room than a mixing room. I do like the idea of running a duct from the other side of the room to feed the extraction vent. I don't know how I'd go about calculating if I need a fan to feed that extraction vent (or if it's necessary at all).

In either case, the HRV ducts still do need to penetrate the wall, and then ducts need to carry that air outside. I spoke with the manufacturer and they said duct runs of over 10 ft will start to cause a decrease in performance. So I'd like to keep those duct runs under 10 ft, which I think is very possible (maybe slightly more difficult if the silencer boxes end up being on the larger size).

PS. You don't need to add additional filters; your HRV has filters on both incoming and extrated air.

Right, I meant if I just used a fan, and no HRV.

You will need filtration for the outside air to keep your gear (and you) in good shape. A simple fan system does not provide that, and dust/smog/etc could be a major problem.

Right! And regardless of filters, you always need some type of screen on the exterior fresh air intake, to keep out bugs, leaves, grass cuttings, floating seeds, and stuff like that. Often forgotten in the joy of building! ... until you find a hornet's nest in your intake one day... or a bunch of old leaves sucked way down the intake duct, to some inaccessible spot.

In fact, for most studio systems I also recommend a course filter on that same intake, after the bug screen: since your silencer box interiors and duct interiors are not going to be accessible ever again, it's a good idea to keep the air flowing through them as clean as possible, free from dust, etc. that could start building up at some points inside the HVAC system. For the same reason, I often put filers inside the return air registers, inside the room, so that even the outgoing stale air gets cleaned up a bit before getting into the silencers and duct work. Yes, it's a pain to go around cleaning an replacing filters every few months, but it's a much bigger pain to have to chop holes in your silencer box or ducts, to clean them out! And when you do your calculations, don't forget to all for the increased static pressure from the filters.

- Stuart -

Greetings Stuart,

And when you do your calculations, don't forget to all for the increased static pressure from the filters.

How do you account for increased static pressure from the filters? I REALLY hope you're going to say that the HVAC people can do it in their sleep and I don't have to worry about it.

a bunch of old leaves sucked way down the intake duct, to some inaccessible spot

Sounds like a great line from a dystopian novel. Or maybe something Don LaFontaine would have voiced-over as part of a movie trailer:
"In a world where a bunch of old leaves are sucked way down the intake duct to some inaccessible spot..."

All the best,

Paul

The static pressure of a filter depends on the flow rate of air going through it - the higher the flow rate, the greater the drop. So you must have your air flow rate worked out before specifying the filter.

Filters should have a datasheet stating the pressure drop at various flow rates. The following is a graph from a datasheet describing the behaviour of several course filters for varying duct sizes. The larger the filter, the smaller the pressure drop for a given flow rate;

Cheers,
Jennifer

Thanks Jennifer!

All the best,

Paul

Progress Update.

I coated the door with the second skin paint stuff. I did two coats, and the second coat was really thick, as that is what the manufacturer recommends. I used a spray gun, and it went on pretty easily. It's a very strange consistency though.





I knocked on the door before and after putting the paint on, and it definitely lowered the vibration of the door.

I cut up the EPS foam to the correct sizes to fit in the panels of the door, but I'm waiting for the paint to completely cure before I put the foam into the panels. The manufacturer says it will take 7-14 days, so it's kind of good I'm going on vacation for 10 days.

I also built the frame of the wall that will be up against the door.



I just need to put the OSB on it before it gets lifted up and into place, then I need to cut the drywall to put in the bays. After that, I can finally start building the inner frame.

I'm still researching ways to make the HVAC system work. I'm wondering if I can have the HRV unit penetrate the inner wall, and add mass to the other side of the frame to make a large cavity for the air to flow through. Basically turning the bays of the frame the silencer. But I'm not sure this will work.

I have a question, and I'm not entirely sure how to ask it. This may not make sense, but bare with me.

So this HRV unit I've been looking at is supposed to be installed to straight through the wall to the outside (going through the sheetrock on the interior, then through whatever the exterior sheathing on the outside). Essentially, the ducts wouldn't be longer than however thick the walls were (maybe 6" max?).

I contacted the manufacturer of the unit, and they said to keep any duct runs under 10ft to make sure the unit operates at it's optimal specs. Is there a way to "trick" the system into thinking it's blowing/pulling air from the outside (short duct run), even though the air has to travel say 10-15ft?

What if I put the unit right onto the wall, and have the short ducts that are on the actual unit penetrate my wall, and in that stud bay I can close the other side of the stud bay using OSB and duct liner, essentially making the bay of the wall a "silencer duct", then use a flex duct to take the air to the exterior wall. If I make the duct large enough, and the volume of the bay large enough, would that help the unit operate at maximum capacity, or without putting too much stress on the system?

Jag94 wrote:Source of the postSo this HRV unit I've been looking at ... Essentially, the ducts wouldn't be longer than however thick the walls were (maybe 6" max?).

I think you misunderstand: without any additional ducts this ventilator will not work with any efficiency simply because the inlet and outlet vents would be too close and too high a proportion of the expelled air would be sucked straight back in by the inlet. Here is your HRV.



You will need to add ducts to ensure that there is a reasonable distance between the inlet and outlet. You will need to add a duct of up to 10ft max. to one or both ports to achieve that. Here is the principle from my build, showing the red ventilator near the bottom right hand corner with grey ducts showing how it extends the distance between inlet and outlet - in my case on both on the outside world side and also on the studio side - and arrows showing the direction the air will travel.



In your case I would also look to do something similar inside the studio, too, otherwise the inlet and outlet, which are are on either side of the HRV's casing, will not reach the far end of your room. To be honest, if you have not yet bought this HRV I would suggest you re-read my recommendation in your other topic (reply #8) and think long and hard about whether you are setting yourself up for disappointment and instead consider something like the Frigate HRV/ERV 120 (here and pictured below) that will be up to the job. I really think the little one you are looking at is aimed at a single small room, such as the smallest bedroom in a house often gets used as a study or office. Your room is bigger and needs a capable machine.