Building a small demountable drum room in my garage

[Twitchy]

I am designing a small room to be built in my garage for the purposes of rehearsing, recording and teaching drums. There will be loud bass players! The neighbours house is 6m from the garage. Fortunately my neighbours are music lovers on both sides.

The property is a rental and here in Australia renters have few rights. I am in no way allowed to alter the existing structure and my room cannot be permanent. Thus why I am building a room within my garage that is easy to disassemble and relocate, knowing that my lease is only two years. My goal in to reduce sound levels as much as possible for under $5000 AU. (that's about $5700 US.) Sorry I can't provide a db requirement.

The garage is single brick with a roller door, side door, tin roof, window and a concrete floor. It also has a slanting roof. It is approx 5m wide and 7m deep. The roof is 3m on the high side and 2.7 on the low side. The side door and the window face towards my yard, not towards my neighbours.

The room I wish to build will be 4.5m x 3m with the roof as high as possible and slanted. I will have a minimum of 40cm between the room and the existing structure along two solid brick walls and approx 1.5m space between the other two walls.

So far my design is to build a room withing a room inside the garage. A two leaf structure. Each leaf having its own independent steel framing. The gap between each leaf will be filled with earth wool. Each leaf will be made from two sheets 16mm of MDF with green glue in between. The entire structure will be free standing and in no way will it touch the garage in any way. I repeat that I am not allowed to alter the existing garage in any way whatsoever. My room must be completely independent.

I have been learning a lot from a user named Stuart. (Thanks Stuart!) He points out that its really a three leaf structure if I include the garage itself into the equation. This is the bit when I'm lost. I'm only a drummer after all!

I'd like to know about any considerations I have missed and if I'm on the right or wrong track to achieving my goal?

[Soundman2020]

Sorry I can't provide a db requirement.

Without knowing that, there's not much we can do to help you! If you don't know what your goal is, we can't help you attain it. This is sort of like saying "I need to get in my car and drive to a place where I really want to go,... but sorry, I don't know where it is, or how to get there. Please help me!"

So far my design is to build a room withing a room inside the garage. A two leaf structure. Each leaf having its own independent steel framing.

Sorry, but that would be a three-leaf structure, NOT a two-leaf structure. The first leaf is the existing garage. If you build two leaves inside that, then you will have a three-leaf system.

He points out that its really a three leaf structure if I include the garage itself into the equation.

Right! If you have no choice, then you can still get good isolation from a three-leaf system, except that it requires more mass and larger air gaps than you would have needed with a two-leaf structure. This diagram explains it all:

2-leaf-3-leaf-classic-walls-diagram-MSM-walls.gif

That shows the difference between coupled-two-leaf walls on the left (with and without insulation), followed by four-leaf, three-leaf, and two leaf versions of the same wall. The second-last (fifth) image shows a two-leaf system that has the exact same thickness of the wall but one third LESS mass, compared to the fourth image, which is what you are planning. You can see that the isolation is vastly superior on the two-leaf, even though it has one third less mass! Not intuitive. But very true. In order to get the same isolation from a 3-leaf system as you would from a two-leaf, you need twice the mass on the middle leaf, and 50% larger air gaps on both sides.

I'd like to know about any considerations I have missed and if I'm on the right or wrong track to achieving my goal?

You can do it, yes, but only if you design it right. What you are proposing is a three-leaf system (assuming that the existing garage wall is only one leaf, such as solid brick). Yes, I get it that you can't modify your existing structure in any way, so you have no choice but to build a three-leaf (or maybe it is a four-leaf, if your existing wall is already two leaves). You still can get good isolation, by increasing the total mass on each leaf (especially the middle leaf) and increasing the size of the air gaps. It can be done. As long as you understand the limitations, and can set an actual goal of how much isolation you need, then it can be designed and built. It won't be cheap, due to the need for so much extra mass, and it will take up mire floor space, but it is possible.


- Stuart -