Best floor isolation method for an attic voiceover booth

[soundgun]

I am assisting in the design of a voiceover booth located in the attic of a 3 story home in Toronto, ON.
To prepare to best isolate the noise from the kids playing video games in the room below from the voiceover booth located directly above, we've taken the following steps:
Laid in strips of 5/8" Gypsum with Greenglue between the ceiling joists on the existing drywall ceiling
Caulked all edges and seams
Blown in cellulose insulation into the joists

Now we are preparing to lay in the floor. I mentioned the hockey puck method as one possible way to further de-couple the floor from the ceiling joists below, then with a layer of GreenGlue between two layers of MDF. Should there also be a layer of 3/4" plywood on the joists before we put in this floor arrangement? Are we fooling ourselves here?

Here is a video tour of the space: https://app.odrive.com/s/a0d5545a-f35f- ... 2-55918886

Thanks a lot for your input, everyone.

George

[stevev]

Hi George,

To prepare to best isolate the noise from the kids playing video games in the room below from the voiceover booth located directly above, we've taken the following steps:

Have you got a db measurement for how loud the video games are, both in the room that they are being played in and also in the proposed booth space? That'll give you a figure on what kind of isolation you already have and what you'll need to achieve for the finished product.

Being video games there's going to be a lot of bottem end so measuring with a properly calibrated meter 'c' weighting, slow is goinf to be necessary.

Laid in strips of 5/8" Gypsum with Greenglue between the ceiling joists on the existing drywall ceiling
Caulked all edges and seams

that's good news. what thickness was the existing ceiling drywall? I'm guessing 1/2 inch?

Blown in cellulose insulation into the joists

probably not ideal, but then again, i don't know the density of cellulose insulation. Ideally you would have used a fibreglass around 30 kg/m3 or rockwool around 50kg/m3.

Now we are preparing to lay in the floor. I mentioned the hockey puck method as one possible way to further de-couple the floor from the ceiling joists below,

By 'hockey puk' i'm guessing you mean using a neoprene pad between the flooring and joists? If so you'll need to do a lot of maths regarding final load per sq/ft to space and thickness the puks correctly. Not enough and they'll compress to much, too many and they'll act as a solid connection.

then with a layer of GreenGlue between two layers of MDF. Should there also be a layer of 3/4" plywood on the joists before we put in this floor arrangement?

Green Glue will probably be helpful, but whether you need another layer of ply is going to be dependant on how much isolation you need from the room below, hence the need for a metered test.

Are we fooling ourselves here?

that depends on the isolation requirement. If you need 110db of isolation, yes, you're fooling yourself...if you need maybe 60db or so then you should be able to get there with attention to detail and a good budget. If you only need 40db then you'll walk it in with attention to detail and a reasonably modest budget.

all the best,

Steve

[Soundman2020]

probably not ideal, but then again, i don't know the density of cellulose insulation. Ideally you would have used a fibreglass around 30 kg/m3 or rockwool around 50kg/m3.

Right! But there's also the issue that blown-in insulation doesn't necessarily end up laying evenly and consistently distributed: there may be voids, pockets, unevenness, or even flanking paths, in extreme cases. I'm not a big fan of blown-in insulation for acoustics.

I mentioned the hockey puck method as one possible way to further de-couple the floor from the ceiling joists below,

Not a good idea. For all of the reasons laid out here: http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173 the exact same principles are at work in your case.

Steve is spot on with his comments: no need for me to add anything more.

- Stuart -

[soundgun]

Thanks, Gents. I did read the FAQ, but wanted to address this unique situation. The Contractor already blew the cellulose, too late to fix that now. I told them to be very careful and make sure it's settled in to all the corners. We'll skip the puck/rubber pad idea and just go with a floor sandwich of ply-GG-ply. 60dB of isolation would be pretty exceptional, IMHO, but they'll need to keep the subwoofer turned WAYYY down for sure. Maybe Dad can have a remote power switch to kill the kid's subwoofer when he's recording, LOL!! I'm always into the practical solutions...

[Soundman2020]

One quick question: Is this vocal booth going to be a free-standing unit with it's own floor? Or will the floor of the room be the floor of the booth? If the former, you might want to consider doing it along the lines of a drum riser, using something like OC-703 as the pad between.

- Stuart -