Seeking acoustic advice for new Project Studio

[cschroeder]

SUMMARY

I currently have a small "recording studio" in my home.
This is a spare bedroom that I've acoustically treated, and while the room sounds "good" to my ears, there are a couple of issues with the space that have proven challenging to workaround.

• - No Room Isolation

• - Limited Storage

• - No Dedicated Vocal Booth or "Live Room"

To solve this, I've been exploring the idea of converting my garage into a dedicated studio space. A "room-in-a-room" style design.

I'm currently in my research phase of this project, and have a handful of general acoustics questions, along with questions more specific to this project.
I've provided some details below that I think may be relevant.

Thanks for taking the time to review and for sharing your thoughts!

EDIT: I've updated this post for format/clarity - hopefully that makes it a bit easier to consume. Apologies for the length!
I've also included some initial sketches to help illustrate what my room looks like currently, as well as a potential layout.

PROJECT DETAILS

ROOM DETAILS

• This will be an attached 2-car garage, with the following details:

• - 3x exterior walls: [composite siding]+[2x4 wood stud w/ R-13 insulation]+[1/2" drywall]

• - 1x interior wall: [1/2" drywall]+[2x4 wood stud w/ R-13 insulation]+[1/2" drywall]

• - 1x 2-car wide garage door (metal, non-insulated, no windows)

• - Unfinished concrete slab

• - Total buildable volume: 111.75" H x 186" W x 234.75" L

ENVIRONMENTAL DETAILS

• - The structure is approximately 500' from main 4-lane road

• - The structure is approximately 1500' from train tracks

• - The structure is approximately 3000' from a shopping center, highway, professional sport arena

• - The structure is in the southern region of the United States - lots of heat and humidity

• - The houses in my neighborhood are fairly close together - I'd say there is <15' distance between my house and the houses on each side

• - There are a few vehicles on my street that are very audible from within my home (motorcycles / diesel trucks)

BUDGET
My initial thought is that I could likely find a fairly nice solution for around $20k. It won't be world-class, but would likely be a significant upgrade over my current room.

GOAL

• - A control room for primarily working on electronic music production / sound design.

• - I would also like a separate space for recording. It would be fantastic if it was large enough for something like a drum set, but I realize this is a small space overall.

• - I want to be able to record/listen at moderate volumes at any hour without disturbing my family or neighbors. (example of expectation: I would love to be able to record and not capture the sound of my neighbor's motorcycle as it drives by.)

QUESTIONS

1. Room Dimensions

• 1.1 I've seen many posts about ideal room ratios, along with links to a variety of room mode calculators.

• I generally understand the value of a room with these properties, however, I'm not sure to what level I need to stress about this given the current buildable volume restrictions. Thoughts?

2. Air Gap

• 2.1 How much does the thickness of the air gap affect the approximate STC?

• 2.2 Does more gap always result in a higher STC value?

• 2.3 Does uniformity of air space surrounding the isolated room matter?

3. Framing

• 3.1 Is there a significant difference between using wood vs metal studs in this application - aside from cost?

• 3.2 Is there a significant difference between using 2x4 vs 2x6, aside from increased air gap?

4. Drywall and Insulation

• 4.1 Dual-layer 5/8" drywall w/ Green Glue (or similar product) vs Single-layer 1 3/8" Quietrock (or similar product)?

• 4.2 Standard R-13 Insulation vs Quiet Batt (or similar product)?

5. Ground Isolation

• 5.1 Do I need to worry about trying to decouple this space from the concrete slab in some way?

• 5.2 If needed, what is the best way to increase ground isolation without a significant reduction in usable room height?

6. Garage Door

• 6.1 I'd like to keep the door in place, as to not modify the exterior appearance of my house. What would be the best way to wall this off on the inside?

• Initial thought is to build a cement-filled cinderblock wall.

LAYOUTS

original_layout.png

updated_layout.png

[gullfo]

welcome.

overall a reasonable plan. i would contemplate the removal of the existing interior drywall and if done carefully, insert between joists to add mass to the outer walls. with 2x4 walls, and 1" air gap between frames, you would have 8" of air (filled with R-30 slightly compress) which is decent. if you have 2x6 walls you'll have 12" of air gap (filled with R-49 slightly compressed). either will be decent given your current structure.

- HVAC - you'll need continuous air circulation (+ the cooling and humidity) so your house system might not be extendable for that - consider a small forced air unit + HRV separate from the house system. probably $5K if you buy the parts yourself. give an HVAC pro studio time to install
- i'd also suggest the roof rafters area gets some of the spray-on insulation to improve thermal, and then make sure your inner ceiling will be fully insulated and damped.

typically the sheet materials (drywall, insulation, cloth, and MLV, etc) will be the bulk of the expenses. so consider your budget realistically as $20K is likely too low for this amout of space.