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Where to get guidance for soundproofing a basement

Stbby

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I’m aiming to soundproof the ceiling of my 1300 sq ft open floor plan basement without covering up the ceiling joists, as adding drywall in the standard way reduces the ceiling height too much and makes the space feel super claustrophobic.

My understanding from one soundproofing contractor is that if I cut two sheets of 5/8 drywall to fit between the joists and do a green glue sandwich, I should be able to get a good reduction in noise transfer.

What I’m a lot less clear on are all the edge cases: what are my options when there’s HVAC stuff in the between-joist spaces? What are my options for the area around the one room that DOES have a drywall ceiling, the bathroom? Are there soundproofing professionals (or experienced DIYers) I could hire just to help give me detailed guidance on all those edge cases? I’m thinking of spending the next month or two doing this project mostly full time and I don’t want to make huge mistakes via ignorance.
Thoughts on how to get the right information/guidance?
 

NiagaraPete

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I’m aiming to soundproof the ceiling of my 1300 sq ft open floor plan basement without covering up the ceiling joists, as adding drywall in the standard way reduces the ceiling height too much and makes the space feel super claustrophobic.

My understanding from one soundproofing contractor is that if I cut two sheets of 5/8 drywall to fit between the joists and do a green glue sandwich, I should be able to get a good reduction in noise transfer.

What I’m a lot less clear on are all the edge cases: what are my options when there’s HVAC stuff in the between-joist spaces? What are my options for the area around the one room that DOES have a drywall ceiling, the bathroom? Are there soundproofing professionals (or experienced DIYers) I could hire just to help give me detailed guidance on all those edge cases? I’m thinking of spending the next month or two doing this project mostly full time and I don’t want to make huge mistakes via ignorance.
Thoughts on how to get the right information/guidance?
I'm getting ready to do the same thing. I do have ceiling height so I can go with 5/8" drywall. I'm wondering if I should use some type of batting in between joists.
 

Doodski

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We soundproofed a rec room and a ping pong room underneath a bedroom. We used 5/8 gyproc with donnacona sheet underneath for sound deadening. It worked well.
 

alex-z

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Low frequency isolation = decoupling. Staggered studs, hat channel, isolation mounts for floor/ceiling.

Mid frequency isolation = insulation. Mineral wool, fibreglass, or recycled denim.

High frequency isolation = stiff mass. Drywall, plywood, brick, etc.

If you want to full isolate a room, you need to combine all 3 approaches. When I do home theatre consulting, people have frequently received mediocre advice from contractors who misunderstand their needs. A 5/8" drywall sandwich with green glue is excellent for mid and high frequency isolation, someone could be singing at the top of their lungs in the next room and not bother you. This is reflected in the high STC rating, which is all that many people reference.

However, this approach is poor for isolating mid-bass and below. Someone turns on EDM music or an action movie, person in the next room might as well be sitting with you.
 
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Stbby

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@alex-z : if the main thing I want is mid-high, and I’m only putting the drywall/green glue sandwich in between joists, but I’m doing a thorough job of using green glue compound all around the drywall to seal it and prevent air gaps, will that do the trick if I don’t care about low frequencies?

Right now I really don’t want voices going between floors. EDM and movie subwoofer stuff is pretty fine.
 

AudiOhm

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My choice instead of regular drywall would be QuietRock...

Ohms
 

Doodski

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My choice instead of regular drywall would be QuietRock...

Ohms
The website is showing gyproc'ers using imperial measurements. Huh? lol.
zzz shotrock.png
 

Dunring

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I've used Quietrock and it really works. They say it's 7 times more sound proofing than normal drywall and I think it's close to that. You can drill 2 inch furring strips into the basement wall and screw into that, so you don't add a lot of depth. Just use a masonry bit and make the strips deep enough to go through the drywall and bite into the strip.
 

alex-z

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@alex-z : if the main thing I want is mid-high, and I’m only putting the drywall/green glue sandwich in between joists, but I’m doing a thorough job of using green glue compound all around the drywall to seal it and prevent air gaps, will that do the trick if I don’t care about low frequencies?

Right now I really don’t want voices going between floors. EDM and movie subwoofer stuff is pretty fine.

Green glue is not meant as a sealant, it is designed to stay viscous to provide constrained layer damping. To seal small gaps, use caulking. For large gaps, closed cell expanding foam.

Yes, two layers of drywall with green glue and sealant will do a good job of blocking high frequencies. You should also place 3.5" insulation inside the wall cavity, this is extremely cheap and greatly enhances mid frequency absorption.

A relatively cheap way to boost low and mid frequency isolation is doing a staggered stud setup, where you have 2x6 top/bottom plates for the walls, and two rows of offset 2x4 studs. Any energy striking the drywall has to travel through the base plates and into the second stud row, several feet of distance, rather than directly through a single row of studs. This approach only costs you 2" of internal room volume + extra lumber, the amount of drywall and insulation used remains the same.
 
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Stbby

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What if I soundproofed the floor, rather than the ceiling? Is that a potentially good option that saves me my ceiling height?
 

alex-z

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What if I soundproofed the floor, rather than the ceiling? Is that a potentially good option that saves me my ceiling height?

For the purposes of soundproofing, the floor and ceiling are the same structure connected by the joists. If you don't want the ceiling in the bottom room to be dropped, you can raise the floor in the upper room. The important thing is that energy not be allowed to transmit straight through the joists, you want the floor or ceiling decoupled, ideally both.
 
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Stbby

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What are my options for soundproofing the floor, and what do I do where the floor stops and a wall begins?
 

sarumbear

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What if I soundproofed the floor, rather than the ceiling? Is that a potentially good option that saves me my ceiling height?
You are in a basement, what is the point to isolate the earth for sound?
 

sarumbear

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He means to soundproof the floors of the rooms above the basement.
Aha! In which case both is the better option. However, the best option is to employ a professional. Define a target noise reduction level and ask what options you have.
 
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Stbby

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Aha! In which case both is the better option. However, the best option is to employ a professional. Define a target noise reduction level and ask what options you have.
Where do I find a professional consultant for this? I don’t have the budget to hire a crew to do this (I got a bid for nearly $40k), but I could hire someone to advise me on doing it on my own if I knew where to look.
 
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