Double garage live room build (preliminary)

[ThorAssistant]

Hey guys,

I'm planning on converting my double garage into a jam room / demo recording facility and I stumbled upon this forum whilst looking for building materials.

I have spoken with a salesman from a sound management company here in Perth West Australia (taking all he said with a grain of salt as i was only looking for a quote on acoustic rated doors) I have concluded that most of what he told me was a load of bollocks designed to pack his wallet.

First off a little about my garage.

It is a brick garage with one wall ajoined to the side of my house, concrete slab floor and fibrocement ceiling. One side is open which will be bricked up with a door as access. My block of land is in a unique position between corner blocks meaning my closest neighbour's house is roughly 20m from the garage.

My goal here is to basically make it so a metal band can play in the room without pissing off the neighbours too much.

My plan of attack is to build a room within a room with stud walls/ceiling totally independent of the existing brickwork. For the walls and ceilings i'll be using 2-3 sheets of 16mm thick gyprock with rockwool packed into the stud cavities.

Now, my original plan was to rip off the garage doors and brick up the voids but this so called expert i spoke with advised me to build a stud wall behind the doors and leave them as is. To my knowledge this will result in a detrimental effect to what i want to achieve.

He also advised me to sheet both sides of the stud wall for added mass etc. but after reading through these forums I've noticed this 3 leaf method is strongly discouraged. He also recommended the use of something called barrierboard which I am a little skeptical on, if only for the exorbitant price.

As I'm only at the planning stage thus far I was wondering whether this highly knowledgeable community could give me some guidance and perhaps debunk what this "expert" has told me.

Attached are some pictures of the garage and a bit of a mudmap ive drawn up in LayOut. (The inner border on the plan is my proposed stud wall taking into account the advice of the salesman to leave the garage doors where they are, assuming a wall thickness of 100mm stud + 32mm gyprock and a 50mm decoupling from the brickwork)

Thanks in advance

[Soundman2020]

Hi there "ThorAssistant", and Welcome!

I stumbled upon this forum whilst looking for building materials.

Good job you did, by the sounds of things!

I have concluded that most of what he told me was a load of bollocks designed to pack his wallet.

It happens, unfortunately. There are many ethical, honest, good acoustic manufacturers and distributors around, but there are also more than just a few not-so-scrupulous places.

It is a brick garage with one wall ajoined to the side of my house, concrete slab floor and fibrocement ceiling.

You probably already know this from the research you have done, but it does no harm to repeat it: The brick and concrete slab are a great start, acoustically, and the fibrocement isn't bad either, provided that it is fairly thick, and depending on what is up above. And of course, the missing walls at both ends of the room are not good news at all!

My goal here is to basically make it so a metal band can play in the room without pissing off the neighbours too much.

You should try to put numbers to that: Measure how loud your band is during a typical session right now with a proper sound level meter (not an app on your smart phone!), and also measure the typical levels around your house at the time of day when you expect to have your jamming sessions going full-on- The difference between the two numbers is "How much isolation you need", and is the key for determining what you need to build, what materials you need, and how you need to build it.

My goal here is to basically make it so a metal band can play in the room without pissing off the neighbours too much.

Perfect!

For the walls and ceilings i'll be using 2-3 sheets of 16mm thick gyprock with rockwool packed into the stud cavities.

Right. If you are going with mineral wool, then you need stuff with a density of about 50 kg/m3 for optimal isolation.

Now, my original plan was to rip off the garage doors and brick up the voids but this so called expert i spoke with advised me to build a stud wall behind the doors and leave them as is. To my knowledge this will result in a detrimental effect to what i want to achieve

Well, you COULD do it the way he suggests, but as you noticed, that would not be optimal. You would need a huge amount of mass on that stud wall to even get close to keeping consistent surface density to match the rest of the building. You'd also lose that amount of space that you need to leave between the existing wall and the new one, to accommodate the door rolls up top.

The only reason you might need to do it that way, is if your local by-laws and regulations do not allow you to remove the garage door. In some places, you are not allowed to change the facade of the house (the way it looks from the street), so the doors might need to stay in place due to that. But if there is no such restriction where you live, then yes, by all means the best option is to take them out and properly brick up the gap. Even if you can't take them out, then the best bet would be to bolt and weld the visible section of door in place, cut of and remove the rolls, then build a brick wall anyway, as close as you possible can to the now fake "doors" that are only there for aesthetic purposes.

He also advised me to sheet both sides of the stud wall for added mass etc.

Yup, it looks like your assessment of this fellow was right! That's a great way for him to sell you more building materials, but bot such a great way to isolate your room.... Yes you do need extra mass, but now it does NOT go on both sides of the frame! It all goes on only one side of the frame.

but after reading through these forums I've noticed this 3 leaf method is strongly discouraged.

Yup. Very much so. Sometimes there is no choice for other overriding reasons, in which case there are methods for compensating, but those methods involve more expense and wasted space, so why do that if you don't have to?

He also recommended the use of something called barrierboard which I am a little skeptical on, if only for the exorbitant price.

Whenever an "expert" wants to sell you some really expensive building materials that have magical properties, then your reaction is spot-on. Extreme skepticism. The more magical and the more expensive, the more skeptical you should be.

The equations for calculating the isolation properties of a wall have no place for inserting the cost of the materials. It turns out that sound waves have really lousy eyesight, and just can't read the price tags as they go by...

The ONLY properties that matter a lot are the mass (surface density) and the resilience (stiffness), and of those two, mass matters more. So you want the heaviest (=most massive) building materials you can get, at the lowest cost. Normally that turns out to be things like brick, concrete, drywall, glass, plywood, OSB, fibercement, and suchlike. IF there is a really unusual situation you might need more exotic materials under some circumstances, but for the majority of cases, just go with the lowest cost mass that will do the job.

As I'm only at the planning stage thus far I was wondering whether this highly knowledgeable community could give me some guidance and perhaps debunk what this "expert" has told me

Not a problem! Consider him duly debunked...

Attached are some pictures of the garage and a bit of a mudmap ive drawn up in LayOut.

Before you do anything about buying materials, the very first thing you should do is to use SketchUp to design your place. Yeah, it takes a bit of getting used to, but there are some great tutorials on-line to help you learn it fast. It really is a very useful tool for studio design, and you really do need to design your place in great detail before you start building it.

As I'm only at the planning stage thus far I was wondering whether this highly knowledgeable community could give me some guidance

You will very likely need to add a lot more mass to yoru existing ceiling before you build your new ceiling below it (which will also need lots of mass). To help design that part, you need to know what is up above that existing ceiling...

I'd suggest that as soon as you have all four brick walls in place, you should render them on the inside (plaster them). That serves two purposes: firstly to get a good seal on the bricks, which are porous by nature, and secondly it adds a bit of extra mass and thickness. If that would be too expensive, then at the very least you should paint them with a good masonry sealant. Air-tight seals are critical to getting good isolation, so sealing that brickwork is very important.

Then within that finished, rendered, sealed outer-leaf, you can proceed to build your inner-leaf, pretty much as you are planning to do.

A couple of things you are missing (or didn't mention yet): Your HVAC system. Yes, you need one: the room will be doubly-sealed air-tight, and having a half dozen musicians jamming away in mid-summer with all the gear and lights on, is going to make it really warm, stuffy and unpleasant, real fast. You need ventilation (properly designed, of course!), and you need cooling / de-humidification. And that all has to be designed in such a way that it does not harm your isolation system...

You also need to think about your electrical system: That can be a major issue in destroying yorur isolation, if not done correctly.

And finally, your access door: It isn't just one door, but two. One in each leaf, back to back, with full perimeter seals around each. And they need to be heavy.... VERY heavy...


- Stuart -

[ThorAssistant]

I'd suggest that as soon as you have all four brick walls in place, you should render them on the inside (plaster them). That serves two purposes: firstly to get a good seal on the bricks, which are porous by nature, and secondly it adds a bit of extra mass and thickness. If that would be too expensive, then at the very least you should paint them with a good masonry sealant. Air-tight seals are critical to getting good isolation, so sealing that brickwork is very important.

Hey Stuart thanks for the quick reply!

Just on the rendering of the bricks on the inside, they are already rendered on the outside of the garage (obviously barring the wall adjoining the house), would it be necessary to do the inside too?

Also you'll notice on my "plan" and in the photos that there are columns on the right hand wall which will obviously impair my ability to put a stud wall close to the majority of the brick, would it be a good idea to brick up the gap between the columns to add some mass? The wall that the garage doors sit on is also double thickness brick to give the doors a recessed look, again would it be a good idea to double brick these (without leaving a cavity)?

If thats the case ill have the back wall built 2bricks thick with no cavity in between.


Regarding the bricks themselves, my resident expert advised me not to use bricks with the holes through the centre as they dont have the mass, which makes sense, but the rest of the brick walls are built from this type of brick, so would that throw out my dampening in any significant way if I were to use solid bricks?

Regarding the HVAC design, will a split system reverse cycle air conditioner suffice? I'm an electrician so installing these is a cakewalk for me.

Cheers

Dave

[ThorAssistant]

Bump!

[ThorAssistant]

Still chasing clarity!

Cheers!

[Soundman2020]

Sorry about the delay! Lots of active threads on the forum, and only a couple of us helping out with answers (Hi Steve!!!). I have too many projects on the go right now! Slows me down a bit, on the forum...

Just on the rendering of the bricks on the inside, they are already rendered on the outside of the garage (obviously barring the wall adjoining the house), would it be necessary to do the inside too?

If the bricks are well rendered on the outside, then you should be OK with that, but just to be safe paint the inside surface with a masonry sealant, or even just with a good quality paint that will seal the pores.

Also you'll notice on my "plan" and in the photos that there are columns on the right hand wall which will obviously impair my ability to put a stud wall close to the majority of the brick, would it be a good idea to brick up the gap between the columns to add some mass?

You don't need to do that. You have two options: A) build the inner-leaf wall far enough back that it clears both pillars, and use the resulting empty gap for your HVAC silencer boxes (no wasted space!), or B) build the inner leaf wall to follow the contour of the outer leaf wall, a constant distance away from it: so you'd have a couple of "kinks" in that wall, where it fits around the columns. Personally, I'd go for plan "A", since it is simpler to do, and it's always tough to find good space for your HVAC silencers in any case.

The wall that the garage doors sit on is also double thickness brick to give the doors a recessed look, again would it be a good idea to double brick these (without leaving a cavity)?

You could if you want: but the main concept here is that the outer leaf should have consistent surface density: at any place on the outer-leaf wall, you should have roughly the same number of kilograms per square meter of mass, that you have at any other place. If one area has significantly higher mass than all the rest, then that's a waste of money. And if one area has significantly lower mass than all the rest, then that's where you need to invest more money, to build it up to the same mass. Acoustic isolation of a room is only as good as the weakest part, so there should be no weak parts. On the other hand, having one small section with much better isolation doesn't help the overall situation much, so there's no need for it. Of course, it does no harm either, so if you already have such an area, just leave it like it is!

Regarding the bricks themselves, my resident expert advised me not to use bricks with the holes through the centre as they dont have the mass, which makes sense, but the rest of the brick walls are built from this type of brick, so would that throw out my dampening in any significant way if I were to use solid bricks?

Well, yeah, strictly speaking bricks with holes have slightly lower mass, but in the overall scheme of things, it's not a huge difference. Bricks are very dense anyway, and thick, so with or without holes, there's plenty there to go around. Find out what is cheaper, and what is easier to build: talk to your contractor, and find out what type he prefers to use, and is accustomed to using. If the bricks cost the same, and the contractor doesn't care, then go with the no-hole type. But of the cost is higher, or the contractor isn't too keen on those, then go with the standard "holey" brick. If you really wanted to get fancy, you could pour dry sand into the holes as the wall goes up, to make up for the lost mass, but that would be a pain, and would probably be overkill. Sand does provide some damping, as well as the extra mass, so it is an option, if you really wanted to do that. But it isn't all that necessary. Especially if your walls will have a good coat of render on them.

Regarding the HVAC design, will a split system reverse cycle air conditioner suffice?

Mini-split systems will work fine for the "H" and "AC" parts of the acronym, but does nothing for the "V" part!: ventilation. In addition to heating / cooling / dehumidifying the air inside the room, you also need to bring in fresh air and exhaust stale air. That implies knocking huge holes in your walls to pass the ducts through, and that implies trashing the isolation you worked so hard to get. So you need to put "silencer boxes" (a.k.a. "baffle boxes") on each such hole, to allow the air to flow through while preventing the sound from getting through.

Why do you need the "V"? Because your room will be doubly sealed air-tight! Unlike a typical house or office, there will be zero leakage: no air will be able to filer in or out through the usual cracks, because there won't be any! One the doors are closed, you will basically have yourself sealed inside a zip-lock bag that is sealed inside another zip-lock bag! Not a good place to put a living, breathing creature... you need to get some O2 flowing in, and pull the CO2 out (along with all the other nasty stuffy smelly stuff). So yeah, you need it. There are equations for figuring out how much flow you need, how fast it has to flow, and the sizes of the ducts.

I'm an electrician so installing these is a cakewalk for me.

Cool! That's the final aspect that most studio builders forget about in the initial design: the electrical system. It also has to be sealed, so no air can flow through the conduit, and also so that the wiring and conduit do not create flanking paths between the leaves, if you want really high levels of isolation. The basic concept here is that you get to have one single conduit that brings your main power feed into each room, then all of the internals are done with surface-mount structured cabling systems, such as those from Legrand, Kalop and others. No holes in walls allowed for outlets, switches, or light fittings! Those would trash you isolation. Just one single feed into the room, then surface-mount distribution from that point, internally. Oh, and use only star grounding, to help keep ground loops and hum under under control.

- Stuart -