Basement studio/drum room advice needed

[ScotcH]

Hello! seeking some advice on a build in progress ... short timeline, but want to do it somewhat "right". So I seek advice from the pros, and the experienced (ie, all the great folks on this forum!)

I am a rock drummer, and producer/mixer/recoding engineer (in my own band, lol). In other words, I like to play loud, and play with a DAW to record our noise making. Not a professional in either job, but it sure is a fun hobby. I also build and race cars ... totally different, but the footwork is sometimes similar

Anyway, I am about to start my basement drum/jam room and sometimes recording studio. I have read a crapload of articles, and watched a tonne of vids. I think I have a good base (and I'm a pretty good study), but need some help to wade through the bullshit and the MANY options. I'm also pretty good with sketchup, so I plan to mock up everything before construction.

Attached photo of the virgin space as it sits right now (just finished gutting it, we've since got the XPS foam up). It's ~quarter of the basement. Here are the specs:

1. Concrete block on 2 walls, 2x6 and 2x4 stud wall on other 2 walls, concrete floor (on grade)
2. 21' x 13', 90" floor to ceiling joists
3. 1 36" door opening, 1 36" window which will be removed and filled
4. 5" HVAC pipes to upstairs floor run in the joists (3x)
5. Some HVAC piping in the space (see image). This can't easily be moved, so will be boxed in.
6. Floor above is 5/8" diagonal pine planks, 5/8" OSB, and 3/4" engineered hardwood.

20201115_151019.jpg

Now the primary goals, in order:
1. Drum/jam room first and foremost
2. Reasonable Sound isolation for rest of house. It's a very open house, and I want to stay married
3. Sound treatment for volume control. We are a rock band, but lately been using IEM for jamming ... so the loudest thing is the drums, though occasionally we'd like to let loose
4. Recording room, maybe mixing. I mix in headphones now, and have gotten quite used to it, so a "mixing room" is low priority
5. Sound isolation escaping to outside the house is low on priority (I've been playing in there for 10 years already with no sound proofing!)

Expectations:
1. I don't need it to be silent outside the room, but above the space is the living room, would like to easily be able to watch TV at reasonable volume with drums going full blast
2. Have some money to spend, but not cubic dollars ... let's say $10k max for complete job of that single room start to finish.

My current approach and thinking:
1. Since this is Canada, the whole basement will be insulated for comfort. The plan is 1.5" rigid foam against the exterior walls, sealed for vapour/moisture. In the studio that means the 2 exterior walls. Against the 1.5" rigid foam, 1 sheet of 5/8" TypeX or quiterock or similar soundproofing drywall.
2. For the interior walls, existing stud walls will be filled with pink batt insulation, 5/8" drywall on outside (rest of basement side)
3. Second 2x4 24" OC stud wall spaced 1" from existing wall, again filled with pink batt. 2 sheet of 5/8 TypeX or quietrock
4. ceiling: Fill joists (7.25") with insulation, iso clips and hat channel, with 2 layer of 5/8" TypeX or quietrock.
5. isolation and caulking in all corners.
6. double door system with good seals.
7. Surface mount electrical and lighting to minimize holes. One main conduit coming in (3x 15A circuits)

Here is the proposed space (partial build to show some details):

basement top 3d.jpg

And the cross section showing the wall details:

basement-west elevation.png

Using this link as a rough guide (any comment on this source?) : https://www.tsib.org/files/STC_IIC_Ratings.pdf

Outside block walls (which I found out is actually 10" think) we have:
10" block, 1.5" foam panel, 5/8" drywall
STC 45-55 (ref 1.4.2.3.1.1). I realize this is 1 leaf. Not sure what the gypsum adds to this, but it's required for fire code obviously.

Inside walls (center of basement) we have:
5/8" gyp, 2x6(or 4) framing, 1" air gap, 2x4 framing, 5/8" gyp, 5/8" gyp
STC 61 (ref 1.2.4.5.5.4)

Ceiling we have:
3/4" engineered hardwood plank, 5/8" OSB, 5/8" plank, 2x8 joists, iso clip+hat channel, 5/8" gyp, 5/8" gyp
STC ~45-55 (2.1.2.2.1.5 is close, but additional 5/8 gyp, iso clips, and 3/4" hardwood should increase this)

Assuming HVAC and piping is properly taken care of, does this seem reasonable starting point? Based on the above, if I can achieve say 50 db of reduction, I would be pretty happy I think.

Now on to my immediate questions:
1. I'm not sure about HVAC. If I use the house HVAC without mufflers, just use some flex duct will it defeat the entire system and other work being done? There are already 2 5" supply ducts into the room, and 1 6" return. Are these workable at all? I can probably build some silencers into soffits ... but room is at a premium.
2. Replace 5/8 type X gyp with 5/8 quietrock silentFX or similar, or Green Glue between the layer? I'm trying to maximize space as well
3. Would using metal studs 25g on interior walls inner leaf be of any use, or just pointless?
4. Is there enough space in the 2x6 and 2x4 double leaf wall to build HVAC silencers? That 10" between drywall panels, which leaves 6" for the air flow (after 1" mdf and 1" duct liner). No go?
5. Should I do anything about the 3 duct running though the joists suppling the upstairs? Just insulation around them, or wrap in something? Or replace with flex?
6. Is it OK to mix 2 leaf and 1 leaf system? I assume that it would perform at the lowest level of all the assemblies, so probably the ceiling in this case.

Ok ... all for now. Please feel free to critique my approach, or shout if I'm totally off my rocker, and I genuinely am super grateful to have this resource available! In the meantime, I'll keep reading and educating myself (and goggling some seriously cool studio builds!)

[ScotcH]

A lot more reading, and lot more thinking ... here is version 2:

- Decouple the inside framing from the joists
- "inside-out" walls on block walls, with air gap (comments on this? Should I add loose pink stuff?)

wall cross section2.jpg

[John Steel]

Hello & howdo' ScotcH?
First thing I would say is don't be in too much of a hurry to build. Form a clear idea of your design and how it's all going to go together before you do anything else - I know it's tempting to pick up power tools and start making things but you'll be glad you waited!

1. I'm not sure about HVAC. If I use the house HVAC without mufflers, just use some flex duct will it defeat the entire system and other work being done? There are already 2 5" supply ducts into the room, and 1 6" return. Are these workable at all? I can probably build some silencers into soffits ... but room is at a premium.

HVAC takes a lot of planning for all kinds of reasons. If you don't build silencers into the system it will definitely compromise the isolation of your room. You also need to make sure that the fresh air supply and stale air exhaust are adequate in all likely conditions (i.e. with a room full of people playing hard, the depths of winter or height of summer). Being able to breath is not optional!

2. Replace 5/8 type X gyp with 5/8 quietrock silentFX or similar, or Green Glue between the layer? I'm trying to maximize space as well

I'm using green glue in my own build as I understand it makes a significant difference to isolation when used correctly but I can't really answer this question as I don't know exactly how much isolation you need. Every aspect of your design should really be motivated by the question "how loud am I (are we)?" Until you know this, the details can't be figured out. I would buy a decent sound level meter and measure how loud your practise and band sessions are exactly in dBs. Then you'll be able to make an informed decision about the density of materials and type of construction needed. I think a 1" air gap is unlikely to give you what you need tho'.

3. Would using metal studs 25g on interior walls inner leaf be of any use, or just pointless?

See previous answer.

4. Is there enough space in the 2x6 and 2x4 double leaf wall to build HVAC silencers? That 10" between drywall panels, which leaves 6" for the air flow (after 1" mdf and 1" duct liner). No go?

I don't see why you couldn't make the silencers integral to the wall but you would have to make sure the cross sectional area was large enough to supply the air at the right velocity.

5. Should I do anything about the 3 duct running though the joists suppling the upstairs? Just insulation around them, or wrap in something? Or replace with flex?

Difficult to say with any certainty, but if they aren't insulated they'll be leaky & also possibly form a flanking path to the rest of the house

6. Is it OK to mix 2 leaf and 1 leaf system? I assume that it would perform at the lowest level of all the assemblies, so probably the ceiling in this case.

Correct. Again, it depends on how much isolation you really need. My guess would be that you probably need a two leaf room with a significantly larger air gap to achieve the transmission loss you need.
Good luck with your project - I'm looking forward to seeing it develop. Best wishes, John.

[DanDan]

i doubt very much if it is practical to isolate a 120dB Drum Kit from a TV room directly above it.
I would stick with the IEMs and check out the rubber drums.

[John Steel]

Hello Dan Dan,

i doubt very much if it is practical to isolate a 120dB Drum Kit from a TV room directly above it.

Yes, me too & certainly not for $10,000. Our friend's requirement is "to easily be able to watch TV at reasonable volume with drums going full blast" which may (or may not) be possible depending on how loud those variables are (including "reasonable TV volume"). Either way, I would measure first, then re-evaluate if neccessary. ATB John.

[ScotcH]

Thanks you, gents.

Lol ... Rubber drums are not an option (at least not a compromise I'm willing to make ). I will take some measurements (already have an SPL meter). However, I've been jamming in the basement for 11 years now, and I'm still married. The last year or so, it didn't even have a wall ... just that carpet hanging there to damp some high end, lol. So "reasonable" to my wife is probably a LOT higher than most people are used to

I'm working through the math now on the wall assemblies, and the HVAC. I think I have some progress. Will post again with further questions. Appreciate the feedback so far!

[DanDan]

You have presented extensive info, well done. But Noise issues may be best approached on a priority basis. If my guess is right about the floor/ceiling, you might do all the other work to achieve a 5-10% improvement. Work on the floor ceiling may render all else moot.

[ScotcH]

I'm somewhat limited in what I can do (willing to do) in terms of HVAC ducting baffle boxes. The return baffle I can make pretty big and follow the accepted best practice in terms of dimensions (ie, Gregwor's simple design).

However, for the 2 supply ducts, they basically need to run through the joist space (currently they are just metal 5" ducts). The joists unfortunately are pretty shallow at 7", and they are spaced 12" OC. So here's my idea:

baffle-box.jpg

NOTE: 1" duct liner not pictured, but would cover all internal surfaces

Basically, using the joists as the sides of the baffle box. The incoming duct is 5", the exit would be 6" with a round ceiling diffuser on it. I could bump that up to 8" for lower velocity as well, though I'm less concerned with the sound of the air itself, and more concerned with sound getting out of the room.

Questions:

1. Is this basically pointless, and would an insulated flex duct just be easier and provide the same level of isolation (ie, basically none)
2. Any though on how to improve this, give the 10 1/4" width between joists, and 7" height? I can make it longer, with more internal baffles, if that would help

[Paulus87]

I'm somewhat limited in what I can do (willing to do) in terms of HVAC ducting baffle boxes. The return baffle I can make pretty big and follow the accepted best practice in terms of dimensions (ie, Gregwor's simple design).

However, for the 2 supply ducts, they basically need to run through the joist space (currently they are just metal 5" ducts). The joists unfortunately are pretty shallow at 7", and they are spaced 12" OC. So here's my idea:

baffle-box.jpg

NOTE: 1" duct liner not pictured, but would cover all internal surfaces

Basically, using the joists as the sides of the baffle box. The incoming duct is 5", the exit would be 6" with a round ceiling diffuser on it. I could bump that up to 8" for lower velocity as well, though I'm less concerned with the sound of the air itself, and more concerned with sound getting out of the room.

Questions:

1. Is this basically pointless, and would an insulated flex duct just be easier and provide the same level of isolation (ie, basically none)
2. Any though on how to improve this, give the 10 1/4" width between joists, and 7" height? I can make it longer, with more internal baffles, if that would help

The general idea looks ok apart from the internal baffles need to overlap, so make each baffle over half of the internal width, it should work out that the cross sectional area remains the same throughout the entire pathway between the baffles.

Paul

[John Steel]

The density of the baffles also needs to be equal to or greater than the leaf that they're attached to.

[ScotcH]

This is my "best effort" HVAC. It's tied into the main house HVAC, so I don't have a lot of options, but for my purpose, I think this should do the job.

Since in the winter I'll be running heat for the whole house, with 5 people in the studio, It's likely to get too hot ... I'm hoping that the HRV dedicated to this one room will do the job to cool the room with outside winter air (at the expense of some energy costs, of course).

HVAC-1.jpg

HVAC-2.jpg

[gullfo]

overall - a good start. the silencer units - you need match pairs one on each side of the walls or very least th box is attached to the inside of the rehearsal room wall. i'd make the silencers half that size though since you really only need a couple of turns and mass+insulation. you can thread a flex duct through it and pack the rest with insulation. once in the room you can route the venting however you need.

one consideration - most homes operate the HVAC sporadically, for a rehearsal room, you need to have the venting operate full time while occupied. even guitarists need oxygen. so consider multi-zoning the AC... and make sure you have at least 8 room changes per hour with 15% fresh air exchange (usually a ERV etc). e.g. room 1000ft3 = 8000ft3/hr ~140ft3/min with 21ft3/min fresh air. so a 30cfm ERV could be sufficient for your room. think about the whole house needs as well since it's an expense...

ultimately 50db is max for a residential construction because of structural transfer but if you put your drums on an isolation platform and damp the interior acoustics you can probably continue to be married.

[ScotcH]

Thanks Glenn,

The HRV will be controlled from inside the room, and is dedicated to the room only (whole house HRV is a separate unit). It'll be a small 60 CFM, and should do the job nicely (room is ~1900 cu ft, so 38 cfm requirement). When the A/C is running, it will feed the house and this room. Multi zone not really an option either due to the duct layout, but worst case, I will add a through wall A/C dedicated to the room.

I've seen the design of a flex duct though the baffle box, and it seems that it's not the best way to go. The baffle box will be between ceiling joist, so I don't mind them being bigger. IN the image above, they are only 48" long (10" wide, and 7.5" deep exterior dimension).

I understand the need for a baffle on each leaf, but I can't afford that space. What I don't understand is why you're suggesting I attach to the inner leaf, not the outer leaf? My plan was to hand the boxes in the joists (outer leaf), and penetrate the inner leaf with a square duct, with plenty of caulk to seal it. No contact with the inner leaf.

[gullfo]

if you attach the box to the outer leaf, you have a gap between the inner leaf and the box. since the air space between the leafs is full of sound, it will "leak" back into the inner space. this may also cause more noise into the upstairs since it's a hole... another option is nesting a pair of solid boxes around the connecting duct that is decoupled but sealed (a layer of duct liner slightly compressed between and flex caulked on the end) so the effect is equiv to the connection to the inner leaf but it's not a hard connection.

yeah, if you're going with the boxes between the joists, then stick with the duct liner. i'm used to building them much larger where the flex/hard duct option is viable.

a minisplit AC should suffice since your air handler is independent.

[ScotcH]

if you attach the box to the outer leaf, you have a gap between the inner leaf and the box. since the air space between the leafs is full of sound, it will "leak" back into the inner space. this may also cause more noise into the upstairs since it's a hole... another option is nesting a pair of solid boxes around the connecting duct that is decoupled but sealed (a layer of duct liner slightly compressed between and flex caulked on the end) so the effect is equiv to the connection to the inner leaf but it's not a hard connection.

Do you mean like this cross-section:

duct.png

And the outer box would be mounted to the joists (outer leaf), and the inner box would penetrate the outer box, and the drywall (inner leaf) in a decoupled way ... do I have that right? I could do this, but being limited to ~8" exterior height, the duct cross section would be 4x6", which is still better than 5" round, but the baffles might be pretty small.

If the box is attached to the outer leaf (the joists), and the inner leaf ceiling is below that, with a square box duct penetration through the drywall, but not touching it (the gap fully caulked), I don't see how that would be worse than having it attached to the inner leaf drywall (sorry for being dense, lol )

I guess the question is, which of these compromises is better for sound getting out. The noise of the air, and outside sounds getting in is lower priority as the main function of this space is a jam/drum practice room, not so much a quite recording studio.