Questions about mistakes I'm about to make

[SoundnoobJnr]

Damn I wish I'd found this forum 3 months ago!!

Thank you for being willing to take the time to offer advice.

Overview:
I have a drum kit in the house and I need to turn an available space into somewhere that the drum kit can be played without other family members trying to kill the kit player.

Budget -Overall, approx $20K (but that includes slab floor, elec, aircon, materials etc). Approx $6,500 to solve these problems including the cost of the plaster board. I've already bought the RC and metal framing materials mentioned below and boxed the area under the plumbing

Hoped for sound result:
Our neighbours on one side are over 80 and hearing impaired (no issue!), on the other side it is a young family and we'd like to annoy them less. At the moment the sound from the kit inside the house makes watching tv almost impossible (with the kit downstairs it is approx 90-100dB upstairs). I don't care if we can hear it, I just want to be able to hear other things as well. So aiming for a possible volume of around 50-60dB outside the drum room.

Assumptions:
1. I won't be doing any electricals, aircon installation or plaster installation
2. The plasterers will be experienced in the use of acoustic caulking and how to seal the room.
3. Aircon will be a split system with pipework coming in through one of the brick walls.
4. Electrical switches/power outlets will be soundproofed.

The room:

Room plan.JPG

The room is on the ground floor of a 2 story house. Concrete floor. Brick walls (no gyprock panels yet) on 3 sides. Standard gyprock stud wall with no insulation on the fourth (longest straight) wall. The ceiling is "I" beam construction (beams running parallel to the long walls) 450 centres and no sheeting on it at the moment.

One section of the ceiling is lowered (2100 height) due to plumbing from the upper story and there is a drain pipe running down the wall (small circle at the bottom left corner of the plan). That pipe will have a small 600x600 (roughly) box section around it.

Under bulkhead.JPG

There is also a beam that protrudes approx 200mm from the 2400 ceiling height (dotted lines in the plan) that makes it feel a bit like two rooms.

The Plan:
Brick walls: Fyrechek (or similar) 13mm to all of the brick walls. The two end brick walls (single brick thickness) will have steel stud walls (quiet stud) with 100mm 32kg batts installed (approx 60mm gap from back of studs to bricks). The gyproc will be attached to the brickwork (and steel stud wall sections) with Rondo 581 RC. I know this may create a 3 leaf system in the double brick section, but the gyprock has to be attached to the wall with some sort of channel and I figured RC was as good as any.

Steel stud wall.jpg

Ceiling: 100mm 32kg insulation batts with a 70-90mm gap above the insulation to the floor above. Two layers of Fyrechek (or similar) 13mm with Green Compound between. Fyrechek suspended from the I beams using Rondo 581 RC.

Stud wall: This wall has bracing ply along the full length of the wall.
Original plan - use 581 RC to attach 2 layers of Fyrechek (or similar) 13 mm with Green Compound between between them to the current gyprock wall - i.e. a 3 leaf system. But after finding this forum (and finding out what a 3 leaf system is) I'm not so sure. I could pull the plaster off the garage side of this wall and insert insulation but I'm trying to avoid messing up more of the house than I have to. Even if I do put the insulation in, it will still be a 3 leaf system.

Problem 1 (Issue 1 in the plan). The stud wall has ply bracing panels under the gyprock which can't be removed. So my options seem to be
a. use resilient channel to decouple the wall but create a 3 leaf system
b. put the extra sheeting on the existing sheet (with another layer of Green Compound?) to increase the mass without decoupling the wall

Which would provide a better TL effect for a drum kit?

Problem 2 (Issue 2 in the plan).
There is an opening from the room that goes into a roof cavity (steel roof) in this corner. At the moment the only plan is to stuff more insulation into the gaps (not a big gap, several small fist sized holes with messy brickwork, sharp bits poking into/out of it - such as a small length of the steel roofing batten) and hope the decoupling of the wall does most of the work. Although, if the stud wall doesn't have the RC on it, I would imagine that the decoupling of the brick wall would be substantially compromised.

Problem 3.
The stud wall is not sitting exactly underneath one of the I beams so there is a cavity over the wall. Half over the sound room and half over the garage/next room. At the moment the only solution that I have is to stuff the cavity with the insulation batts. Are there any other options for this?

Gap over wall.JPG

[Paulus87]

Damn I wish I'd found this forum 3 months ago!!

Thank you for being willing to take the time to offer advice.

Overview:
I have a drum kit in the house and I need to turn an available space into somewhere that the drum kit can be played without other family members trying to kill the kit player.

Budget -Overall, approx $20K (but that includes slab floor, elec, aircon, materials etc). Approx $6,500 to solve these problems including the cost of the plaster board. I've already bought the RC and metal framing materials mentioned below and boxed the area under the plumbing

Hoped for sound result:
Our neighbours on one side are over 80 and hearing impaired (no issue!), on the other side it is a young family and we'd like to annoy them less. At the moment the sound from the kit inside the house makes watching tv almost impossible (with the kit downstairs it is approx 90-100dB upstairs). I don't care if we can hear it, I just want to be able to hear other things as well. So aiming for a possible volume of around 50-60dB outside the drum room.

Assumptions:
1. I won't be doing any electricals, aircon installation or plaster installation
2. The plasterers will be experienced in the use of acoustic caulking and how to seal the room.
3. Aircon will be a split system with pipework coming in through one of the brick walls.
4. Electrical switches/power outlets will be soundproofed.

The room:

Room plan.JPG

The room is on the ground floor of a 2 story house. Concrete floor. Brick walls (no gyprock panels yet) on 3 sides. Standard gyprock stud wall with no insulation on the fourth (longest straight) wall. The ceiling is "I" beam construction (beams running parallel to the long walls) 450 centres and no sheeting on it at the moment.

One section of the ceiling is lowered (2100 height) due to plumbing from the upper story and there is a drain pipe running down the wall (small circle at the bottom left corner of the plan). That pipe will have a small 600x600 (roughly) box section around it.

Under bulkhead.JPG

There is also a beam that protrudes approx 200mm from the 2400 ceiling height (dotted lines in the plan) that makes it feel a bit like two rooms.

The Plan:
Brick walls: Fyrechek (or similar) 13mm to all of the brick walls. The two end brick walls (single brick thickness) will have steel stud walls (quiet stud) with 100mm 32kg batts installed (approx 60mm gap from back of studs to bricks). The gyproc will be attached to the brickwork (and steel stud wall sections) with Rondo 581 RC. I know this may create a 3 leaf system in the double brick section, but the gyprock has to be attached to the wall with some sort of channel and I figured RC was as good as any.

Steel stud wall.jpg

Ceiling: 100mm 32kg insulation batts with a 70-90mm gap above the insulation to the floor above. Two layers of Fyrechek (or similar) 13mm with Green Compound between. Fyrechek suspended from the I beams using Rondo 581 RC.

Stud wall: This wall has bracing ply along the full length of the wall.
Original plan - use 581 RC to attach 2 layers of Fyrechek (or similar) 13 mm with Green Compound between between them to the current gyprock wall - i.e. a 3 leaf system. But after finding this forum (and finding out what a 3 leaf system is) I'm not so sure. I could pull the plaster off the garage side of this wall and insert insulation but I'm trying to avoid messing up more of the house than I have to. Even if I do put the insulation in, it will still be a 3 leaf system.

Problem 1 (Issue 1 in the plan). The stud wall has ply bracing panels under the gyprock which can't be removed. So my options seem to be
a. use resilient channel to decouple the wall but create a 3 leaf system
b. put the extra sheeting on the existing sheet (with another layer of Green Compound?) to increase the mass without decoupling the wall

Which would provide a better TL effect for a drum kit?

Problem 2 (Issue 2 in the plan).
There is an opening from the room that goes into a roof cavity (steel roof) in this corner. At the moment the only plan is to stuff more insulation into the gaps (not a big gap, several small fist sized holes with messy brickwork, sharp bits poking into/out of it - such as a small length of the steel roofing batten) and hope the decoupling of the wall does most of the work. Although, if the stud wall doesn't have the RC on it, I would imagine that the decoupling of the brick wall would be substantially compromised.

Problem 3.
The stud wall is not sitting exactly underneath one of the I beams so there is a cavity over the wall. Half over the sound room and half over the garage/next room. At the moment the only solution that I have is to stuff the cavity with the insulation batts. Are there any other options for this?

Gap over wall.JPG

Hi,

Your construction seems very complicated and not consistent between all walls/ceiling.

The black and white of it is this:

In order to achieve your goal, there is only one way within your budget - the outer walls (outer leaf) and ceiling must be as heavy as possible and completely sealed air tight. Then you must build an inner set of walls (inner leaf) completely decoupled, not attached in anyway to the outer leaf. The only place they will attach is the massive concrete slab. There must be an insulated air gap between the two leaves, this air gap needs to be as big as possible (within reason) measured from mass to mass. It must be insulated with cheap low density insulation, completely filled but not compressed.

One penetration for electric, one penetration for AC and two penetrations per room for ventilation. Each of those penetrations must be done properly. For electrical it should be as small as possible and then completely sealed with a non hardening caulk. Same for the AC pipework. For the ventilation you must build silencer boxes which are sized correctly for your ductwork, which must be designed properly as to have low enough velocity to not produce audible noise within your space, while at the same time providing enough fresh air for the amount of people inside, as well as exhausting stale air.

All doors and windows must be designed so as to have the same surface density as your walls/ceiling. They must be airtight when closed by using suitable seals.

All of the above is for sound isolation purposes only and anything short of the above is a waste of time if you are trying to achieve high isolation (TL 60+) down to low frequency (like a kick drum). There is no other way.

All your talk of 3 brick walls and 1 stud wall, three leaf systems, resilient channel and insulation unfortunately is only going to get you average results. I suggest you either do it properly or not at all or continue the way you are and live with the compromises.

Paul

[SoundnoobJnr]

Hi Paul,

Thanks for taking the time to reply.

I realise this is well short of the ideal size/shape/structure for a drum room but it's all that I have available. Unfortunately, the budget is limited to what I have and the lack of width in the long part of the room makes it impossible to build internal frame/walls with the necessary gaps and still have a usable space inside. With new walls on both sides, the width of the room comes down to at most 1.8-2.0m at the narrow points and possibly less. So I guess that means that it will be a compromised outcome, but I'd still like to avoid making the situation worse than it has to be.

There are no windows and only 1 door which will be re-built when everything else has been done. Each of the walls (and ceilings) has different characteristics and I've tried to do something that *might* reduce the sound transmission through each. I realise that in an ideal world the room should be regarded as a whole but with such a complex shape I don't think that is realistic in this case.

If the TL can only be 50 (or less) then so be it.

With that in mind, which is the better option for the long wall, two new layers of heavy plasterboard fixed to the existing plaster (and two layers of GG) or two new layers of plasterboard on RC attached to the existing plaster (with one layer of GG)? Or, will it make no difference?

Assuming an airtight seal around the interior of the plaster work, is there a better option for the air gap above the wall than just stuffing insulation in?

Thanks,
Brad.

[Paulus87]

Hi Paul,

Thanks for taking the time to reply.

I realise this is well short of the ideal size/shape/structure for a drum room but it's all that I have available. Unfortunately, the budget is limited to what I have and the lack of width in the long part of the room makes it impossible to build internal frame/walls with the necessary gaps and still have a usable space inside. With new walls on both sides, the width of the room comes down to at most 1.8-2.0m at the narrow points and possibly less. So I guess that means that it will be a compromised outcome, but I'd still like to avoid making the situation worse than it has to be.

There are no windows and only 1 door which will be re-built when everything else has been done. Each of the walls (and ceilings) has different characteristics and I've tried to do something that *might* reduce the sound transmission through each. I realise that in an ideal world the room should be regarded as a whole but with such a complex shape I don't think that is realistic in this case.

If the TL can only be 50 (or less) then so be it.

With that in mind, which is the better option for the long wall, two new layers of heavy plasterboard fixed to the existing plaster (and two layers of GG) or two new layers of plasterboard on RC attached to the existing plaster (with one layer of GG)? Or, will it make no difference?

Assuming an airtight seal around the interior of the plaster work, is there a better option for the air gap above the wall than just stuffing insulation in?

Thanks,
Brad.

Ok that is good that you understand that this will be a compromised space isolation wise as I would hate for you to do all this work and spend all this money and not be satisfied with the end result!

I do not have a totally clear vision of exactly how your walls and ceiling are built yet, I find your diagram confusing. From what I understand:

- you have 3 brick walls on to which you want to put RC and drywall?
- the fourth wall is a stud wall. Does it have some sort of panelling on both sides of the studs or just one side?
- above this stud wall is a massive gap between it and the ceiling?

So, where the cavity is above the wall you'll need to panel over it to continue the leaf. Insulation alone can be considered air... it will not stop much sound at all actually going through it. Can you not panel down from the ceiling and attach to the wall so that the whole space becomes enclosed?

Something to bear in mind is for every doubling of mass you'll only gain about 6db of TL. That is to say, if your brick walls already have a surface density of 200kg/m2 (estimate) then adding layers of drywall (10kg/m2) over it is not going to make much (if any) difference at all. Even if you added another layer of bricks in front of the existing brick walls, you'd only gain 6db extra of isolation. Though it's true that every little counts, it's a massive amount of work and cost for a seemingly small result. It is the good old law of diminishing returns.

Adding RC is not an effective decoupler in all honesty. The problem is you still have some sort of physical connection between the existing and new walls and the air gap between those two walls is very, very small. This means you will have a high cavity resonance and low TL between the two. Filling that cavity with insulation will lower the resonance a bit, but not very much. Have a look at some online calculators for membrane traps, that's effectively what you're building here.

The stud wall will always be your weakest link since it has the least amount of mass. Therefore your total isolation will be governed by the TL of that wall. You need to build that wall to have an isolation level of whatever you deem acceptable, and settle with that. What is on the other side of this stud wall? The outside or another room in the house?

Paul

[SoundnoobJnr]

- you have 3 brick walls on to which you want to put RC and drywall?

Yes

- the fourth wall is a stud wall. Does it have some sort of panelling on both sides of the studs or just one side?

Yes 10mm standard plasterboard on both sides

- above this stud wall is a massive gap between it and the ceiling?

Not quite. At the moment there is no 'ceiling' only the bottom of I beams that support the floor above. The wall sits between 2 I beams. My plan is to attach RC to the bottom of the I beams (seen with poly insulation between them in the picture) and then plasterboard (2x13mm fire rated plasterboard) to the RC.

So, where the cavity is above the wall you'll need to panel over it to continue the leaf. Insulation alone can be considered air... it will not stop much sound at all actually going through it. Can you not panel down from the ceiling and attach to the wall so that the whole space becomes enclosed?

Yes, I will.

Something to bear in mind is for every doubling of mass you'll only gain about 6db of TL. That is to say, if your brick walls already have a surface density of 200kg/m2 (estimate) then adding layers of drywall (10kg/m2) over it is not going to make much (if any) difference at all. Even if you added another layer of bricks in front of the existing brick walls, you'd only gain 6db extra of isolation. Though it's true that every little counts, it's a massive amount of work and cost for a seemingly small result. It is the good old law of diminishing returns.

The drywall on the bricks is for 2 reasons, First there is a termite barrier running down the wall that looks awful! Second, my wife said "THERE WILL BE PLASTERBORD ON THIS WALL!!". The RC is being used to attach it to the wall because the wall is too uneven to put the drywall onto directly

Adding RC is not an effective decoupler in all honesty. The problem is you still have some sort of physical connection between the existing and new walls and the air gap between those two walls is very, very small. This means you will have a high cavity resonance and low TL between the two. Filling that cavity with insulation will lower the resonance a bit, but not very much. Have a look at some online calculators for membrane traps, that's effectively what you're building here.

Thank you for that suggestion, I've just found someone who's trying to get away some very thin layers of insulation they don't need.

The stud wall will always be your weakest link since it has the least amount of mass. Therefore your total isolation will be governed by the TL of that wall. You need to build that wall to have an isolation level of whatever you deem acceptable, and settle with that. What is on the other side of this stud wall? The outside or another room in the house?

The other side of the wall is the garage. A bit of extra noise in there isn't much of a problem. I am thinking about cutting some holes in that side of the wall and sliding some poly insulation in between the studs.

Brad.

[Paulus87]

- you have 3 brick walls on to which you want to put RC and drywall?

Yes

- the fourth wall is a stud wall. Does it have some sort of panelling on both sides of the studs or just one side?

Yes 10mm standard plasterboard on both sides

- above this stud wall is a massive gap between it and the ceiling?

Not quite. At the moment there is no 'ceiling' only the bottom of I beams that support the floor above. The wall sits between 2 I beams. My plan is to attach RC to the bottom of the I beams (seen with poly insulation between them in the picture) and then plasterboard (2x13mm fire rated plasterboard) to the RC.

So, where the cavity is above the wall you'll need to panel over it to continue the leaf. Insulation alone can be considered air... it will not stop much sound at all actually going through it. Can you not panel down from the ceiling and attach to the wall so that the whole space becomes enclosed?

Yes, I will.

Something to bear in mind is for every doubling of mass you'll only gain about 6db of TL. That is to say, if your brick walls already have a surface density of 200kg/m2 (estimate) then adding layers of drywall (10kg/m2) over it is not going to make much (if any) difference at all. Even if you added another layer of bricks in front of the existing brick walls, you'd only gain 6db extra of isolation. Though it's true that every little counts, it's a massive amount of work and cost for a seemingly small result. It is the good old law of diminishing returns.

The drywall on the bricks is for 2 reasons, First there is a termite barrier running down the wall that looks awful! Second, my wife said "THERE WILL BE PLASTERBORD ON THIS WALL!!". The RC is being used to attach it to the wall because the wall is too uneven to put the drywall onto directly

Adding RC is not an effective decoupler in all honesty. The problem is you still have some sort of physical connection between the existing and new walls and the air gap between those two walls is very, very small. This means you will have a high cavity resonance and low TL between the two. Filling that cavity with insulation will lower the resonance a bit, but not very much. Have a look at some online calculators for membrane traps, that's effectively what you're building here.

Thank you for that suggestion, I've just found someone who's trying to get away some very thin layers of insulation they don't need.

The stud wall will always be your weakest link since it has the least amount of mass. Therefore your total isolation will be governed by the TL of that wall. You need to build that wall to have an isolation level of whatever you deem acceptable, and settle with that. What is on the other side of this stud wall? The outside or another room in the house?

The other side of the wall is the garage. A bit of extra noise in there isn't much of a problem. I am thinking about cutting some holes in that side of the wall and sliding some poly insulation in between the studs.

Brad.

Okay that's starting to make a bit more sense now.

the fourth wall which has drywall on both sides, are you going to treat that as the completion of your outer leaf and then build another wall in front of that wall with RC and drywall? That is what I would suggest you do in your case.

It would be good if you could take the drywall off of the studio side, fill it with insulation and then put those drywall panels on the other side (garage side). Then when you hang the RC and drywall on the open frame you will have a fairly good sized air gap.

Paul

[SoundnoobJnr]

No, at the moment the room is only 6'8'' wide at the narrowest points. Putting an extra wall along there will just make the room too narrow. I guess I'm trying to find the most effective way of increasing the effectiveness of that wall without making it too much thicker.

From what you've said it sounds like the next best option would be to find a way to fill the wall with insulation. Am I right that after that the last option is adding layers to the studio side?

[Paulus87]

No, at the moment the room is only 6'8'' wide at the narrowest points. Putting an extra wall along there will just make the room too narrow. I guess I'm trying to find the most effective way of increasing the effectiveness of that wall without making it too much thicker.

From what you've said it sounds like the next best option would be to find a way to fill the wall with insulation. Am I right that after that the last option is adding layers to the studio side?

Insulation inside/covering the wall will do almost nothing to reduce sound going through the wall, it'll just take the edge off of very HF. It will absorb the cavity resonance, which will stop the walls ringing like a drum.

If you're not going to complete the inner leaf by adding another wall infront then there is little point adding drywall on RC on the brick walls. Yes, it may look better but as that inner leaf will not be complete it will not actually help much in reducing sound.

You'll just have to leave drywall on both side of that stud wall, complete the envelope so that it meets the ceiling on both sides of the wall and live with a fully coupled, shorted out two leaf system.

It may be enough isolation for your needs, it will be anything but silent but will certainly be quieter than before.

Paul

[SoundnoobJnr]

Thanks for your help Paul.

It's appreciated!

Cheers,
Brad.