Gigalittle Studio Build Thread

[Gigalittle]

Hi Everyone.

I have browsing the forum for a few years now but this is my first post, so please be gentle if I forget anything...

I am planning to build a 2 room studio in the basement of my home in central Massachusetts USA. I would like to record full bands (including drums) and also have a place to jam without disturbing the neighbors. The basement is a walk out - the back half is above grade, the front half is poured concrete. The existing above grade walls are 2x6 construction. The joists are 2x10's spaced 16" off center. The height from the concrete floor to the bottom of the joists is 7' 10". I am shooting for a finished ceiling height of about 7' 6". There will be bulkheads for HVAC trunk lines (not shown) where the ceiling height will need to be lower (about 6' 8").

Top View with Dim.jpg

I would like to achieve approximately 60 dB of isolation. My initial measurements of my band playing in the basement are typical for rock music - about 100 dB average, with peaks about 115 dB. The closest neighbors are about 50 feet away. At present when we rehearse in the space "as is" the music is clearly audible (especially the bass guitar) from the property line. We have only had one noise complaint so far which was during the summer (when the neighbors had their windows open) I have discussed it with them and it really is not an issue as long as we stop playing around 9:30pm. My goal would be to achieve enough isolation that just a subtle "thump thump" is audible from the property line - allowing us to play later into the evening. The local noise ordinance states that to be in compliance the noise must not exceed the ambient noise level by more than 10 dB at the property line. Unfortunately our neighborhood can be very quiet at night so the ambient level is low. I would guess around 40 dB, but my meter will not register below 60 dB.

I would also like to isolate enough that my wife can relax upstairs while we are playing without going too nuts. The house is two stories. The bedrooms are on the 2nd floor and are already pretty well isolated from the basement. You can hear a bit of bleed through the duct work when we play, but that is about it. The living area directly above is another matter. Again my goal would be to isolate to a subtle "thump" of bass through the floor so watching TV, for example, would be possible.

My plan is to build independently framed double stud 2x4 walls for 2 rooms in the basement: a control room and live room. I will not be doing any angled walls so that the basement would be convertible to other uses like a home theater or a rec room if we ever need to sell the house. My budget for this project is about $20,000

Basement Floor Plan Web.jpg

The ceilings will suspended from isolation clips and hat channel. I have already consulted with a structural engineer and have completed sistering of joists that needed to be reinforced to support the additional load of the 4 layers of 5/8" drywall.

I am getting ready to beef up the existing subfloor with 2 layers of 5/8" drywall between the joists, and will also beefing up the exterior walls on the above grade sections between the studs.

My main concern at this stage is what to do about the existing ductwork which is servicing the living room, kitchen and dining room on the ground floor. There is a fair amount of it: 2 large trunk lines for main send and cold air return, which hang below the joists, and several branching ducts which connect to registers on the ground floor. In all this ductwork covers about 25% of the total ceiling area. This ductwork is not part of the studio design. (For studio HVAC I will be running separate ducts later)

Ducts and Pipes Web.jpg

More Ducts Web.jpg

The problem as I see it is that all this ductwork is likely going to be the weakest link in my isolation. I am trying to figure out the best way to deal with it.

My first idea was to "box it in" like this:

Duct Solution 1.jpg

The compromise here is that this would be creating a 3 leaf situation in these areas but the ducts would at least be completely sealed off from the studio (behind 4 layers of drywall). The decoupled air gap would be limited to 1 5/8" between the inner leaf and the "boxed in" duct but there would be an additional 9 inch air gap between the middle leaf and the subfloor. The rest of the ceiling would have an air gap of about 10 5/8" where there are no ducts interfering due to the additional 1 1/4" blocking on the joists to align the isolation clips. I am wondering if the inconsistent air gap would "average out" for isolation performance or would the smallest air gap govern?

I have also seen some builds where it was done more like this:

Duct Solution 2.jpg

The compromise here is that the outer leaf has inconsistent mass since there is no way to beef up the subfloor above the duct, but the decoupled air gap is a consistent 9 3/8" throughout. I am also concerned that the ducts would only be behind 2 layers of drywall and there are direct openings through the subfloor where the registers penetrate into the rooms above, so the outer leaf actually is not completely sealed.

So which is a better compromise: an inconsistent air gap and some 3 leaf situations, or, an inconsistent outer leaf with a consistent air gap?

If I go with solution 1 which my "gut" tells me is better, would I be just wasting the money for the extra drywall?

Thanks in advance!

[Gigalittle]

Hi Again,

Just posting some additional info that may be of help...

I had the band over last night and had an opportunity to take some additional sound level readings.

The SPL in the basement while jamming: ~ 110 dB (C weighted)
In the living room directly above: ~ 80 dB
At the property line (closest to neighbor): ~ 70 dB
In the 2nd floor bedrooms: ~ 60 dB

Assuming a "quiet night" ambient noise level of ~ 40 dB, means I need to get to around 50 dB at the property line, which requires 60 dB of isolation.
I am only currently getting between 30-40 dB isolation from the structure as is...

More info on the existing structure:

The above grade walls are 2x6 construction with 1/2" OSB cladding. Outside of that is just lightweight vinyl siding. There is R30 insulation already in place which I will remove and replace after beef up. I definitely need to add a lot of mass here.

The ceiling / floor deck assembly is 2x10 joists, with 3/4" OSB decking, on top of that is 3/4" hardwood oak flooring. Also R30 insulation between the joists.

My plan is to beef up the exterior walls, and ceiling with 2 layers of 5/8" drywall, caulking and sealing each layer with 3/8" backer rod (as per Rod's Book), then build decoupled 2x4 interior walls with 2 more layers of 5/8". The ceiling will be suspended using isolation clips and furring channel also 2 layers of 5/8".

I have 68 sheets of drywall coming on Friday and will get started on the beefing up this weekend. I will start on the less complicated areas now, and wait for some feedback on my previous post before dealing with the ducts and other obstructions.

I am also wondering if I should invest in green glue for the beef up? Will I need it to obtain the isolation I am looking for? If I opted to only use green glue on one leaf would it be of more benefit on the outer "beef up" leaf or the inner leaf, or does it really not make a difference? (of course I know both would be best, but the stuff is very expensive)

Thanks again for reading!

[Gigalittle]

I apologize if this is premature, but I am still wondering about the best way to approach my ceiling. In any case please excuse me for "bumping".

[DasProductions]

Hi Steve, I have the same situation at my ceiling with ducts going in between the joists, were you able to find which method is best for adding more mass?

[Soundman2020]

Hi Steve, and Welcome!

Sorry about the delay in getting back to you: I've been tied up for several weeks on a big project, and it looks like nobody else is answering right now!

The height from the concrete floor to the bottom of the joists is 7' 10". I am shooting for a finished ceiling height of about 7' 6".

That should be possible, from the way you describe it.

I would like to achieve approximately 60 dB of isolation.

That's a reasonable goal to shoot for. Doable, but not easily.

I would guess around 40 dB, but my meter will not register below 60 dB.

Maybe you need a better meter?

I would also like to isolate enough that my wife can relax upstairs while we are playing without going too nuts. ... Again my goal would be to isolate to a subtle "thump" of bass through the floor so watching TV, for example, would be possible.

If you isolate the room to 60 dB, then you'll certainly achieve that too.

My plan is to build independently framed double stud 2x4 walls for 2 rooms in the basement: a control room and live room. I will not be doing any angled walls so that the basement would be convertible to other uses like a home theater or a rec room if we ever need to sell the house. My budget for this project is about $20,000

The plan is fine, but the budget might be a bit tight. That works out to about US$ 30 per square foot, which might not be enough to get the high levels of isolation you are looking for.

My first idea was to "box it in" like this:

Yup! That's what I would do...

The compromise here is that this would be creating a 3 leaf situation in these areas

Sometimes you have no choice, and you just have to go 3-leaf. In those cases, you can compensate for the third leaf with more mass on the middle leaf.

If I go with solution 1 which my "gut" tells me is better,

Your gut is right! Listen to your gut... (well, for this case at least.... ! )


- Stuart -

[Gigalittle]

Hi Stuart,

Thanks for the feedback, extremely appreciated.

It has been a while since I last posted. I just wanted to post a status update on my build so far. Beef up is progressing, but very slow and tedious. It is just myself working bit by bit on nights and weekends. I will hire some help when I get to the HVAC and electrical, but I am hoping to do as much on my own as possible to keep on budget. There is no deadline, but I would like to finish before I die of old age! At this rate I hope to be ready to start framing by spring. Here are some pics.

[andy_eade]

Hi Steve,

Looks like you're making some great progress, but I do agree that the beef up is tedious work - though absolutely necessary for you to achieve your goals it would seem. I sure you're already aware of this, but just wanted to mention since I don't see it in the photos - make sure to add the cleats around the perimeter of the beef up. It looks like you have used screws and I believe those should be removed and the holes filled once the cleats are added.

Keep up the great work - it'll all be worth the effort in no time!

Andy.

[DasProductions]

"It looks like you have used screws and I believe those should be removed and the holes filled once the cleats are added. "

Hi Andy,

I'm glad you wrote this because I've been confused about this and been trying to better understand it.
If you beef up with one layer of sheetrock, it shouldn't be a problem to take out the screws once the cleats are installed. What would be the best way to achieve this if you install 2 layers? because i thought it's better to caulk one installed layer at a time. Any help would be greatly appreciated Andy.

Thank you,
Jim

[andy_eade]

We can see what the experts here say Jim - I only know enough to get you into trouble

You are correct to say that each layer should be caulked (with backer rod too) before moving to the next later. In Rod's book he suggests using nails fired into the joist, and not through the drywall to hold each layer prior to the cleats. I'm not sure if there is an advantage to this over screws (I'm sure there is else he wouldn't be suggesting it). I was wondering if it was because the screws punch a hole in both the Sheetrock layers and subfloor at the same place. There is a small advantage I see with screws too - they ensure the layers are pulled up tight to the subfloor, but I suspect the nails are the way to go since they don't puncture holes in the drywall.

Let's see what the resident experts have to say. I'm eager to know also as I soon will be undertaking this same process

Wishing you all the best,

Andy.

[DasProductions]

Thank you very much Andy

[Gigalittle]

I went with screws to hold the drywall in place (short ones for the first layer, and longer for the 2nd), but I did add the "safety" cleats and put the crossbracing back in place afterwards (will post some pics later).

I did this because it was the only way to physically hold the drywall in place (while working by myself). I also feel it helps hold the drywall tight to the subfloor as Andy mentioned. The screws weigh more than the drywall they "displace" and I caulked the screwheads so they do not create a hole in the drywall so I don't really feel this will create a problem.

I suppose if the drywall was too tight it could raise the resonant frequency of the assembly (like tightening a guitar string) which would be bad, but when I knock on the drywall it does not "ring" and the frequency of the "thud" is lower than when I started. I feel it is really just about getting the mass up there, held securely, and airtight. There is already a noticable reduction in sound transmission in the areas I have beefed, so I am pretty confident, but I would also be interested to know what the experts on the forum have to say about this.

Thanks!

[DasProductions]

Excellent info Steve, thank you.

[Gigalittle]

Here are some more pics, showing the newly installed cleats and the reinstalled cross bridging. I was able to reuse the cross bridging members previously removed by trimming them to fit the now shallower joist bay cavities.

Ducts Boxed.jpg

Cross Bridging Replaced.jpg

[DasProductions]

Great work Steve!
Please keep the pictures coming, great motivation because i'm working in slow motion

[Soundman2020]

Looking good! I love seeing good progress on studio builds!

- Stuart -