ventilation help for detached garage music studio project

TomSkill

Hello,

I am working on renovating a 22x26 detached garage into a music studio. I live on Vancouver Island B.C, Canada, 30 meters above sea level about 2 km from the ocean. It's usually between 2-10 degrees Celsius in the winter (but occasionally gets below 0) and usually between 20-24 in the summer (sometimes gets in the 30's but rarely). It does rain a lot.

The "drum room" will have between 1 and 5 musicians playing in it. A max. of three amps will be generating additional heat. (some power amps will be located in the hallway so that heat won't need to be accounted for). The "control room" will feature a tv, computer monitors, lights, and usually 1-2 people but may have upto 6 in it. Rarely would there be more than 8 people in either room... maybe if I ever finish this and have a party....lol.

The garage no longer has a garage door, ( removed it and filled it to match the existing siding and structure) but just one 36 inch door way. I have already double dry walled and green glued the existing ceiling. (part of the sound proofing process). The rooms I build will all have dropped ceilings with an additional two layers of drywall on them, and the walls will be 1 foot thick, double stud walls with separate sill plates. I plan on using two layers of 5/8 with green glue to start, and will beef up 1 more layer if required.

I will be making one hallway (roughly 5x12, 8 foot ceiling) that will have the main door at one end, which will lead to a set of "communicating" doors at the other end. (basically two doors that face each other to assist in soundproofing). This room is the only one with a window.

These communicating doors will lead to a "drum room" (12 feet wide, 21 feet long, 7'6" high) with a dropped ceiling. The room will be air tight. I'm using multiple layers of drywall (using the two leaf technique, foot thick walls), green glue between the drywall and acoustic sealant on all edges and seams.
This room has a second door in it beside the entrance to the room that leads to the "control" room, which will be 12 by 14 feet, with the same 7'6" height, dropped ceiling, thick, air tight walls.

The outer leaf (existing wall) has r20 batt insulation. I will be adding Roxul safe n sound insulation to the inner leafs of the walls. The attic has blown in insulation. So, between using acoustic sealant on all edges and seams, a sealed tight vapour barrier (already installed) and all that insulation, it's gonna be airtight rooms.


So, as I'm flying along trying to go to work and build this thing, I have realized I neglected to think about the fact these rooms will be airtight... lol. I think I like air... so!

I am having issues deciding on how to properly ventilate the rooms!

Here is what I'd like to do, and I hope someone can provide some direction or advice...

1. I can't afford a proper HVAC system right now. Eventually I'd like to connect one to the venting I hope to install.

2.What I can afford is to put in vents, run them outside to a home built "fan house" that will supply fresh air in, and draw the air out of the room. I have technical info that will help me determine fan size for CFU of these two rooms...(but I'm having a hard time assimilating it, understanding it and applying it!!!)
I am a little hung up on whether I should use four fans in total (2 for intakes, 2 for out, so each room has a separate in and out system) or if I should use 2 large fans, one in, one out for BOTH rooms and split the vents up in the attic...?


3. I want to use 6" flexible insulated duct pipe. The reason is that it can laid out in the attic in a large loop, which will help prevent air turbulence noise, and the transfer of noise through the pipe from the fan or from the rooms...

4. I'd like to locate all vents in the ceiling, as it's proving very difficult to come up with a way to put vents at floor level... however if I'm told this is required I'm prepared to do it.. I'd just rather have them all in the ceiling, for sound proofing, ease of build and having them farthest away from mics, etc.

5. I plan on using electric heaters in the winter if required (rooms are heavily insulated though)...


Anyway, this is as far as I can see so far! Any assistance, advice or confirmation would be greatly appreciated!

beenthere

6" flex is TOO small. You won't get enough air through it.

Trying to move enough air through it, will actually cause noise issues.

I've done sound studios before. They can be interesting, to say the least.

While you may not be able to afford an A/C unit/system at the moment. Its best to find out what size you will need, and you will need one. And then install the ductwork for it now. And use that duct system for your ventilation air requirements.

Your not going to get away with less then 2 tons of A/C for your set up.

You will NEED a min fresh air ventilation of 15 CFM per person. 8 people in 1 room, thats 120 CFM, well outside the range of a 6" flex to deliver quietly.

For noise consideration, no supply should be less then 7" for 100 CFM. 6" for 60 CFM. You don't want to be over 2 db from your supply and return registers when the system runs.

You should install a supply trunk line sized for a max of 600 FPM in the attic. It can be either acoustical lined sheet metal, or ductboard.

Gary in WA

Won't the flex ducting capture the moist coastal air depositing water as there is twice as much surface to contact as straight pipe? Will the sounds travel through the double walls via the continuous floor decking under them?

Gary

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beenthere

The outer jacket of the flex duct will be the same temp as the air.

Flex duct is a great sound attenuator. Shouldn't be any transfer.

Gary in WA

Isn't there usually a dehumidifier or something to remove the moisture when piping air from outside to a heated room full of electronics? Before his permanent system is in....

"Will the sounds travel through the double walls via the continuous floor decking under them?" --- think flooring with two walls to trap sound, connected by sheathing to transfer noises.

Gary

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beenthere

Usually. If someone wants to build a recording room/studio. They build the whole thing at one time. So no, usually, there isn;'t any dehumidifier installed or needed. Since the equipment produces a large amount of heat. The A/C runs long enough to remove enough moisture that the RH is plenty low.

Ted White

This is a very effective use of flex in a soffit muffler to attenuate sound. The flex alone won't attenuate much sound, however when deployed in a specialized structure like this, the results are quite dramatic