New Home Rehearsal/Recording Studio build. advice?

[Gregwor]

it looks like one layer of quietrock to cover the room, 37 sheets, would be about $2250, 24 bottles of green glue, about $500

Quietrock is basically drywall with Green Glue Compound already in between the sheets and packaged as a single unit. You wouldn't need Green Glue. However, you will need a caulk to seal everything. Please, do NOT use Green Glue Sealant!!! That stuff is honestly 100% useless. The Green Glue Compound is amazing stuff, but the Sealant cracks after a while no matter what. Stay away from it. I recommend DAP Dynaflex 230 in white around our area because it is cheap, easy to work with/clean up, and it actually works great!

with well made doors, how much isolation can I expect to get if I were to build up a single high mass airtight layer on the existing interior?

You can calculate the estimated isolation in decibels at any frequency you want using the formula below.

20*LOG(frequency*surface density in kg per square meter)-47.2

Sadly, with Quietrock, this formula wouldn't be accurate because the CLDM (Constrained Layer Damping Material) in the product will drastically change it's performance. They have charts on their website showing estimated performance.

Greg

[Bretton M]

More budget items, got quotes in on doors, and quietrock.

my custom sliding doors are going to be about 2000 apiece, with two entry points that those need to go on, one wall is 4000, two walls is $8000. One layer of soundproofing material as I've been planning it (37 sheets of quietrock, 20 bottles of green glue, and the supplier put in 7 units of CertainTeed SilentFX Putty) is 3700, so two of those is 7400. Already with one layer I'm at 7700, and with two layers 15,400. Add in the lumber, rockwool, silencer boxes, etc, and I'll definitely be clearing 20k to make a floating room.

Trying to keep my anticipated budget to 10,000, with room to go up to 15,000 after unexpected costs get added on.

a layer of cheap sheeting (OSB or cheap drywall) 600
Rockwool: 1200

has me up to $9200. Still need to figure out my silencer boxes, and will need to have some electrical work done.

Is it worth it to rip the existing drywall and OSB off the walls to replace the pink insulation with Rockwool? or would I be just as well off to just start adding mass to the existing wall via quietrock? if I rip off the old drywall to put in rockwool, is it worth it to put a layer of cheap sheeting up before the quietrock? or just go straight to quietrock.

should I be looking at those metal spacers to get a small air space between the studs, and a layer of mass, like isotrax or whatever brand name is in my area?

also, how do I go about putting up the quietrock, and mounting the electrical outlets, the heater, and anything else we might want on the walls? Because we don't want to penetrate the leaf with screws right? just glue everything up?

thanks.

[Gregwor]

my custom sliding doors are going to be about 2000 apiece

Care to share details about the brand, specs, etc? Those are cheaper than I anticipated which makes me question their quality.

One layer of soundproofing material as I've been planning it

Don't take this comment as being rude, but we never use the anything with the term "soundproof" in it around here because it implies that it is in fact possible to achieve silence and well, that's simply impossible. Words like isolation and transmission loss are the correct terms to use.

37 sheets of quietrock, 20 bottles of green glue

Green Glue is pricey and as I mentioned in my last reply, you don't need it. Maybe the person quoted you Green Glue Sealant and not Compound?

a layer of cheap sheeting (OSB or cheap drywall) 600

When it comes to drywall, luckily the heavy stuff we want is only $23.48 at Home Depot right now.
CGC Firecode Core (Type X) 5/8-inch x 4 ft. x 8 ft. Drywall Gypsum Panel

The "ultralight" which we don't want (heavier the better) is more expensive at $23.98.
CGC UltraLight Firecode X 5/8-inch x 4ft. x 8ft. Drywall Gypsum Panel

Still need to figure out my silencer boxes, and will need to have some electrical work done.

These are both fairly expensive aspects for sure. Duct liner alone is wicked expensive and you can't just buy a little bit of it as it comes in big rolls.

Is it worth it to rip the existing drywall and OSB off the walls to replace the pink insulation with Rockwool?

It is not worth replacing the insulation. You can see in this picture that different insulation yields very small changes in isolation performances.

Insulation Density In MSM Cavities.jpg

or would I be just as well off to just start adding mass to the existing wall via quietrock?

I wouldn't use QuietRock for beefing up your outer leaf. I would seal all of the stud bays with DAP DynaFlex 230, then use Green Glue Compound between the existing sheathing and a layer of 5/8" heavy drywall held up with cleats. Of course, apply a second layer of caulk after the drywall is up to ensure a great seal and fill any voids with the required surface density. Note, you'll need to move the cleats to a different position once the caulk is dry. Moving them will allow you to caulk where they were initially.

if I rip off the old drywall to put in rockwool, is it worth it to put a layer of cheap sheeting up before the quietrock? or just go straight to quietrock.

In order to get a worthwhile increase in isolation, you're going to have to rip off the old drywall in order to seal and beef up the existing outer leaf. As I pointed out above, cheap sheeting IS the stuff we want. Adding an extra layer of 5/8" drywall underneath the QuietRock would help for sure, but I wouldn't say it will make it a lot better. I'm guessing that you might gain a few dB more of isolation tops.

should I be looking at those metal spacers to get a small air space between the studs, and a layer of mass, like isotrax or whatever brand name is in my area?

Not if you want it to sound great in there. All of those devices have a weight limit which means it's really hard to safely mount acoustic treatment devices. Also, if you figure out the math and you can safely anchor the devices on the sheathing, you pretty much have to install a layer of OSB on the hat channel first so that you can freely mount your devices anywhere --> you still have to avoid putting any screw through spots that might have a stud or joist in the way. If you were to accidentally hit a stud or joist, ultimately you short out the system and completely ruin the isolation the clips+hat were supposed to provide. Also, the clips+hat systems are wicked expensive. Installation has to be done very very carefully.

also, how do I go about putting up the quietrock, and mounting the electrical outlets, the heater, and anything else we might want on the walls?

In an inside out build, it's great because you can run everything through the studs/joists just like a normal house build. The fabric you would put over the framing hides all of that and the outlets and things like that appear to be flush. If you don't do inside out, you have to surface mount everything because you cannot have any holes in your sheathing as that would ruin your isolation.

Because we don't want to penetrate the leaf with screws right? just glue everything up?

Screws are fine. Holes are not.

Note: As I said above, if you're using resilient channel or clips and hat, you cannot put a screw where it has the potential to hit frame work!

Greg

[Bretton M]

cool cool.

Here are the quotes I got, this is all I know about the doors and what was included in the quietrock/greenglue quote:

Door quotes.PNG

door details.PNG

quietrock quote.PNG

I certainly don't take any corrections as being Rude, that's why I'm here after all so please excuse my layman's term.

for my "cheap sheeting" option, I was looking at 1/2" ultralight on homedepot.ca, and it's showing 14.48 a sheet, and 7/16" OSB is 15.20. so 37 sheets of either of those, I was rounding to $600. 23.48*37+12% gives me about $1,000 for a layer of firecode drywall. If I'm doing

since I'm looking at one wall of construction now, are we still looking at the exterior sheeting, and the interior sheeting being the two leaves of a 2-leaf construction?

I just removed the 3 exterior facing windows and boarded them up with OSB. in doing so I found that there's no house-wrap under the siding. I wonder if I should take the siding off and work on beefing up the exterior wall and sealing it from the outside, since I should be taking it off anyway to add the house wrap?

I still need to beef up both sides of the wall, so I'll end up with OSB and firecode drywall with green glue in between, on both sides of the studs. Looks like quietrock is out of the budget.

budget:
doors: 5000 (also have the man-door to account for)
firecode drywall: one layer outer, one layer inner, $2000
OSB, one layer inner: $600
green glue: one layer outer, one layer inner, $1000
vapour barrier: $100
Electrical: $?
silencer boxes: $?
DAP Dynaflex 230: 5.97 a bottle, not sure how many bottles I need
insulation: (reuse existing)

process:
rip off existing drywall and OSB, pull insulation.
install new doors
Seal outer wall with Dynaflex
add strips of firecode drywall with greenglue between studs
pull all electrical wires to consolidate to one entry point.
replace insulation
sheet with OSB
sheet with greenglue coated firecode drywall
drill entry point for electrical
have electrician run all electrical, surface mounted
build silencer boxes
drill entry points for ventilation
mount silencer boxes
caulk around electrical and ventilation ports

am I just about ready to start working?

*edit*
I can't seem to find the instructions on how to calculate the size required for the silencer boxes, and how to construct them. I'm sure there must be a thread, could someone point me to the right one? I found Gregwor's silencer box with the algebraic dimensions, but how do I calculate the what X value I need?

[Gregwor]

I just messaged Bretton through social media but I'll recap a few things here for you all:

I advised him to get the old school heavy firecode drywall instead of the ultralight stuff as we need mass here.

For the outer leaf beef up, if you have to pull the siding to install barrier then 100% add the mass to the outside. It will take a fraction of the time and be sooooo much easier to do!

I also recommended that he buy sliding doors designed by a company specifically to address sound isolation. The fact that his quote did not include any glass thickness specifications and seem to be constructed from plastic scares me. He said he just needs a good 4 foot wide opening to move gear in about might be pushing towards using a conventional door which would save him a lot of money.

He needs 3 doors. 1 to separate inside spaces and 2 that will go outside. Does anyone have have recommendations about how to deal with a slab that will handle rain and such?

Greg

[Gregwor]

I can't seem to find the instructions on how to calculate the size required for the silencer boxes, and how to construct them. I'm sure there must be a thread, could someone point me to the right one? I found Gregwor's silencer box with the algebraic dimensions, but how do I calculate the what X value I need?

Since plan to use the existing electric heater in the space and not worry about cooling, you only need to replace ~25-30% of the air compared to a ducted system.

Needed flow rate = (at least 8 air changes per hour X cubic feet )/60 min

30% fresh air = Needed flow rate x 0.3

Once you know how many CFM you're pushing/pulling through your system, you can find out roughly how big the duct needs to be to hook up your inline fan by referencing a standard friction rate of .10 inches per 100 feet of lineal duct chart such as this:

Residential Duct Sizing Guide.png

From there, you can calculate the cross sectional area of the duct. Here's a quick list to save you from doing the math yourself:

Duct CSA:

4” RD duct = 12.57 sq in. Double = 25.14 sq in.
5” RD duct = 19.63 sq in. Double = 39.26 sq in.
6” RD duct = 28.27 sq in. Double = 56.54 sq in.
8” RD duct = 50.27 sq in. Double = 100.53 sq in.
9” RD duct = 63.62 sq in. Double = 127.23 sq in.
10” RD duct = 78.54 sq in. Double = 157.08 sq in.
12” RD duct = 113.1 sq in. Double = 226.19 sq in.

Area of a rectangle = width x height
Area of a oval duct = major radius x minor radius x π
This is for a true oval, not a flat oval like HVAC duct though :-S
Area of flat oval = π (minor radius)2 + [(major diameter- minor diameter) x minor diameter)]
OR
[(π minor 2) / 4] + 3 (major - minor)

You can see in the list above that I've indicated what double the CSA would be. This is the minimum cross sectional area that the path inside your silencer box needs to be. If you could quadruple it instead of doubling it, that would be better. Just for fun, let's say you need a 10" round duct from your fan. Your box would then need to be at least 157.08 sq inches inside. So, if you had a simple square air path in your box, you could take the square root of 157.08 sq inches and end up with ~12 1/2".... let's be cool and increase that a bit to play it safe. So, 12 3/4" putting us at a healthy 162.56 sq inches. So, in the silencer box design image I made, 12 3/4" would be the value for "x".

Also, we should make sure that our velocity is good coming out of the box into your room.

In my 10" round duct example, let's say that the air velocity out each baffle will be 162.56 sq inches. In order to calculate the air velocity (which we need to be slower than 300 feet per minute), we need to convert our opening size from square inches to square feet. So, we simply divide our sq inches by 144 to get that value. 162.56 sq in / 144 = 1.1289 sq ft.

So, to get the air velocity, we do this:
30% fresh air CFM / 1.1289 sq ft = velocity in ft per min

If for some reason the air velocity is faster than 300 feet per minute, you will have to increase the size of the opening feeding your room. Or, if you have the space to have a bigger silencer box, simply make the entire thing bigger because it will also improve your insertion loss!

Lastly, you have to find an inline duct fan to push or pull the air in/out of your room. To make life easier (for now until audiomutt, Chris, and I fine tune my static pressure calculator) I would recommend using 0.2 inches water gauge to spec out your fan.

If you use a legit brand such as Fantech, their website has a calculator on it where you can enter your CFM and such and it will show you if the fan will perform as you need it to. Don't worry if the fan is slightly over spec as you can put a speed controller on it to slow it down.

Fan Spec Static Pressure.png

Greg

[Bretton M]

Progress report: Demo has begun:

demo 1.jpg

demo 2.jpg

definitely not going to use any ultralight drywall, going for fire-code heavy stuff. Going to scrap the idea of sliding doors and go swinging.

here's a shot of my heater to let that be known, going to just re-mount this once I've got the walls done:

heater.jpg

I don't remember getting too hot jamming in there last summer, but if I do, I was considering putting a window air conditioner in the garage next to this space, and ducting it through a silencer box into the space. This is before me knowing anything about ductless mini splits, so there's that to look into as well.



looks like I'm dealing with 4865 cubic feet in there.

[Paulus87]

It's looking good so far, looks like you and greg have got things all figured out.

Just a note of caution so you don't make the same mistake I did. How are you going to deal with ventilating your roof deck? Are you going to have a hot roof or cold roof?

This important detail needs to be worked out early to avoid interstitial condensation forming on the under side of your roof deck and causing you to tear down all your hard work!

Paul

[trodden]

Good timing! I'm about to start a similar build! Following this one for sure.

[trodden]

I

For the outer leaf beef up, if you have to pull the siding to install barrier then 100% add the mass to the outside. It will take a fraction of the time and be sooooo much easier to do!
Greg

Hmmm.. I just may go this route. I've got five windows to remove as well as beefing up my outer leaf on a 15x30 garage. I may just pull off all the siding and just beef it all up from the outside.

This is what i'm working with regarding the outer leaf. Cedar siding on plywood, over plank walls.

[Bretton M]

Are you going to have a hot roof or cold roof?

what should I do? it's a cold roof now, but it's ventilated, and I need to remove that ventilation to get isolation. the ceiling currently has pink insulation up against the inner sheeting, soffits on the underside of the roof outside the wall. I was thinking the easiest way to seal it would be to add sheeting going straight up from the wall and add my extra mass there, leaving some open triangular cross sections on the outside of the wall. If the soffits are left open, would that keep it from creating a resonating chamber/third leaf?

(material to add indicated in red)

roof.png

so there's a catch 22 between isolation and ventilation for the space within the trusses how do I get around that?

[Paulus87]

Are you going to have a hot roof or cold roof?

what should I do? it's a cold roof now, but it's ventilated, and I need to remove that ventilation to get isolation. the ceiling currently has pink insulation up against the inner sheeting, soffits on the underside of the roof outside the wall. I was thinking the easiest way to seal it would be to add sheeting going straight up from the wall and add my extra mass there, leaving some open triangular cross sections on the outside of the wall. If the soffits are left open, would that keep it from creating a resonating chamber/third leaf?

(material to add indicated in red)

roof.png

so there's a catch 22 between isolation and ventilation for the space within the trusses how do I get around that?

Actually, you can maintain isolation and ventilation at the same time if you do it correctly. Here's a diagram I drew to show you how to do that:

Cold roof assembly.jpg

You need a continuous free air air flow from your soffits all the way up to your ridge vent. There needs to be a 50mm gap (2") between your roof deck and your drywall. So, install some 50mm battens to the rafters and then install the drywall on the bottom of those battens. This Is your outerleaf, so you would install however many layers you need here and seal it air tight. You connect those layers to your walls, which seals the ventilation cavity as well as sealing your outerleaf. Make sure your rafters (and I'm assuming ridge beam?) are strong enough to take the load, check with an engineer.

Below that you would build your inner leaf assembly. So, you will have a double leaf assembly with a ventilated roof on top.

If your roof already has a ridge vent and soffit vents then double check with the Owens Corning calculator here to make sure you have enough inlet and outlet ventilation (please do not overlook this, it's extremely important that you have the correct amount otherwise you're going to be tearing everything down again to fix it!)

https://www.owenscorning.com/roofing/co ... calculator

I know in the UK if the building is less than 10m wide with a pitch of less than 35 degrees then you can get away with just 70mm soffit vents installed every 160mm, but it may be different in the USA.

You might be thinking, "isn't this a triple leaf assembly" No, not really. The roof "leaf" is not really a leaf since it is incredibly leaky, you have continuous holes in the soffits and ridge, so do not view it as a third leaf it is simply a rain screen to protect your double leaf assembly.

The alternative to this would be to convert your roof to a warm roof (or I think you call it a "hot" roof in the states). This type of roof completely does away with the need for any ventilation, and is how a lot of new houses are being built to save energy. This would be where you take off your tiles (or shingles, whatever you have as your waterproof layer) install a vapour control layer completely sealed with no gaps, then cover that with thick rigid foam insulation and then your final roof layer over that.

Having just gone through a nightmare condensation problem in my own studio I highly recommend you sort this out ASAP, it does not take long to completely destroy your whole roof and ceiling. I am worried about the pink fluffy you have up tight against the roof deck... make sure you have the correct roof ventilation in there otherwise you'll be in for a nasty surprise.

Paul

EDIT: I just noticed from your pics that you have what looks to be OSB already on the bottom of your rafters? and the ventilated roof deck is above that OSB correct? That's cool, you can leave it like that and just beef up that ceiling. It will save you having to install battens and cut in drywall between your rafters. All it means is you will not be able to use the depth of your rafters as part of your double leaf cavity, but you can just make your inner leaf ceiling lower to achieve the required gap that you need for your MAM assembly. Hope that makes sense? Still double check that your current rafters and Ridge beam can take the extra weight if you do need to beef that OSB up.

[Bretton M]

I do have OSB on the inside of the rafters/trusses. if you go back to my original post, there are a couple photos of the new trusses before the roof covering went on. A contractor did that part for me, up to where it had to pass a building inspection so there is vapour barrier behind the OSB, so if I'm making another inner wall, I'll have to take off the OSB to remove the vapour barrier, put the OSB back up, and put my vapour barrier on the inner leaf.

I made another diagram just now, which now that I look at it next to yours again, looks like it is a simplified version of yours. brown is wood, red is "leaf":

leaves.png

that look like it's going to work?

[Paulus87]

Yep, exactly, that’ll work just fine. The only thing you might need to add in order to stick to code is a fire stop at the top between the two walls, so check that out. If you do need to add it then see if you can just use rockwool instead of a solid connection, I’m not really clued up on Canadian regulations.

Paul

[Bretton M]

Progress report

more RIP AND TEAR (I've also been playing the new Doom game)

IMG_20200509_1501371.jpg

IMG_20200509_1501157.jpg

IMG_20200509_1501046.jpg

before adding mass to the outer layer, I suppose I'll have to snip off all those nail ends poking through that hold the siding on.

on the side that goes into my garage, I suppose I will have to seal up the peak there, where it goes higher than the other wall, making my outer leaf on the inside of that wall, much the same as I would be doing with the ceiling itself, so that should be fine.

now, since it will work to keep the ceiling with the same construction and add to it, can I save myself some work by leaving the vapour barrier in place? and if so, how do I account for it when finishing the rest of the vapour barrier? I have some options in mind:

vapour barrier.png

next steps... (if I can skip taking down vapour barrier):
- have electrician pull the wires,
- filling in the framing where the garage doors used to be (well, where one still is, gotta take it down still) and put in all the outer-leaf doors.
- caulking everything and self-levelling-concrete-ing the floor.

stop me if I'm going to mess something up!