Mix room in unfinished attic. Advice?

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allbaldo
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Mix room in unfinished attic. Advice?

Post by allbaldo » Sun Aug 10, 2014 9:44 pm

Hello!

I received some excellent advice from the forum a while back, regarding a room I'd been using to mix in. As it turns out, we ended up buying a different house, which is fortunate, since the room I was mixing in was 10' x 10' x 8'. Yeah? ugly.

In our new house, we have a 3 car garage with a decked attic above it, which I get to convert to my new mix room. I'm super happy about this, because I'll have a good deal more space to work with. It has a pitched roof, which is less than ideal, but it has a reasonably high apex, and with any luck, will allow me enough headroom to make a nice space.

I've included a very bad SketchUp of the space as it currently sits. This is done as a sort of cross section, because my SketchUp skills are severely lacking. The lines you see illustrate where how the framing lays out. To help make sense of it all, I've included a picture of the space.

Some particulars. (Measurements are in feet and inches):

1. The dimensions of the floor space is 20' long x 15' 4" wide, and the hight is 11' 2" at the apex of the roof.

2. As you can see there are cross members between the sides of the room. These are a concern, as I'm pretty sure they can't be removed. The bottom of the cross members are 8' 6" from the floor.

3. The floor sits on 2x12 joists, and the floor is decked with 1/2" chip board.

4. There are 2x4s about 21 inches high from the floor, that connect to the 2x6's that support the roof. Hopefully I've illustrated them.

5. Though I haven't figured out how to illustrate it in SketchUp, there is a full staircase that leads up to this room from the garage. As it is now, when you go up the stairwell, then step to your right into the space. There will need to be a wall at the top of the stairs with a door. This door will be hard to negotiate, because of the pitched roof, so that will be a challenge.

The main focus of the room is mixing/mastering, but I would like to occasionally record drums in the room too. I do some TV music, and have to track drums occasionally. The drumming is secondary, but I'd like to provide for it. I'm a guitarist first and foremost, and will likely build an isolation cabinet for tracking occasional guitars.

I'm fairly close to my neighbors, so some amount of isolation is desirable. I won't be tracking drums constantly, and It's just me doing it during the day, so I don't have to go super far with it, but I'd like to do what I can. It's a fairly quiet neighborhood, and I don't want to make enemies. Most of the time I'll be mixing, and there won't be a problem, as I don't mix that loud to begin with.

I'm located in Tulsa, Oklahoma. USA.

I should have about $10,000 to work with for construction, HVAC (I'm thinking mini-split), and acoustic treatments. I can build basic bass traps, etc, so that might save some money. My first thought is to use resilient channel, and 2 layers of sheetrock for the walls, but I'd love to hear some suggestions. It'd be nice if I could find a way to de-couple the floor as much as possible, and install hardwoods. Again, opinions and suggestions are appreciated. I've spent hours reading, but still don't feel confident about how to approach this.

I should also mention that since this is above the garage as opposed to the house itself, and I'm mixing for the most part, I'm not as concerned about disturbing my family. I do the loud stuff when they're not around.

Many thanks in advance for any help in getting me started!!

Stephen

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Post by Snarl 12/8 » Mon Aug 11, 2014 12:53 am

I didn't read your whole thing, so maybe you answered this, but are you concerned about being "up to code" at all? Just from the photo and codes around here, without blowing in a dormer, you will just have a narrow tunnel once you bring the side walls in enough and add enough insulation to be up to code.
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Post by floid » Mon Aug 11, 2014 3:39 am

are the floor joists tied to a center laminated beam or span the entire floor width/ how are they spaced? this will affect how much weight you can safely add to the floor.

the 2x4s form what is called a knee wall. they are structural, tho most knee walls are an even 4ft interior dimension. (better leverage against the rafters, and making it possible to use a full sheet of osb - which adds shear strength)

behind the knee wall, check to see if the soffit (flat part of eave) is vented. it should be. you need to maintain this venting thru to the ridge, using styrofoam channel between every rafter pair before applying insulation. you should also confirm that you have a vented ridge or eave vents.

the A-braces are structural. if they're run every other rafter, you'll need to come back with the remainder and use this plane for your ceiling. you can't insulate all the way to the ridge w/o compromising yr venting.

my gut tells me 2x6 rafters won't support more than a single layer of drywall.
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Post by allbaldo » Mon Aug 11, 2014 8:43 am

Hello Floid. Thanks for responding!
floid wrote:are the floor joists tied to a center laminated beam or span the entire floor width/ how are they spaced? this will affect how much weight you can safely add to the floor.
I think I'll have to tear into the floors a bit to answer this. I'll check that out. The joists definitely run the short distance, and not the long. They run the same direction as the rafters do in the pics, if that makes sense.
floid wrote:the 2x4s form what is called a knee wall. they are structural, tho most knee walls are an even 4ft interior dimension. (better leverage against the rafters, and making it possible to use a full sheet of osb - which adds shear strength)
Sorry, I'm a complete newbie at this. What is osb?
floid wrote:behind the knee wall, check to see if the soffit (flat part of eave) is vented. it should be. you need to maintain this venting thru to the ridge, using styrofoam channel between every rafter pair before applying insulation. you should also confirm that you have a vented ridge or eave vents.
I see that there are only a few soffit vents around the house, and only 2 in the space I'm working with. There's a vent on the face of the house that which you can see near my left arm in the photo, which would end up behind a wall I think I'd need to build in the space behind me in the picture. There's a pitch similar to the sides of the room in the front with some complex angles, and I figured I'd end up making a flat wall at each end of the room.
floid wrote:the A-braces are structural. if they're run every other rafter, you'll need to come back with the remainder and use this plane for your ceiling. you can't insulate all the way to the ridge w/o compromising yr venting.
The braces span each rafter. I'm going to try to figure out if there's a ridge vent up high. Hard to tell.

quote="floid"]my gut tells me 2x6 rafters won't support more than a single layer of drywall.[/quote]

I had wondered about that. Especially since the rafters are at angles, which would likely distribute the weight oddly. I'll have to do some thinking on that part.

Again, thanks for responding!

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Post by JWL » Mon Aug 11, 2014 11:20 am

Definitely get a structural engineer to sign off on any building you do, to make sure the structure can handle the additional weight you will add.

Regarding treatment, the pitched ceiling won't really hurt you that badly, you will just have 5 reflection points not 3. Details here: http://realtraps.com/rfz.htm

Also, you will want to find out where the bass buildups are in your room, and put a bass trap everywhere you hear a strong bass buildup if possible. Details here: http://realtraps.com/lf-noise.htm

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Post by Snarl 12/8 » Mon Aug 11, 2014 12:56 pm

I just started worrying about the room below that room. Are the studs 16" or 24" on center for the room below that? You might need to reinforce downstairs before you can do much upstairs, which will tear into your budget.
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Post by allbaldo » Mon Aug 11, 2014 5:49 pm

Thanks for the responses folks!

Everything appears to be on 24" centers. I'll definitely be asking a structural engineer what I can pull off. I guess that's my next step.

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Post by floid » Mon Aug 11, 2014 7:34 pm

osb, organized strand board, aka chipboard. the randomized fibers make it stronger than milled or ply wood under shear stress conditions, though it's weaker under others, like kicking it. 7/16 osb over 2' center joists is fine for storage, but not so much for live loads - i'd replace it with 3/4 osb or preferably plywood.

i'd be very surprised if the downstairs studs weren't on 16" centers. but 2' centers above will limit what you can do soundproofing-wise (mass and more mass), and esp if the joists aren't hung on a center beam, i'd say any kind of floor decoupling scheme is a bad idea. hardwood over decking won't have enough mass to keep the floor from singing with yr kick.

i'll stress the venting thing again, it controls both heat and moisture - your roof decking can fry in the summer and mildew in the winter. problem is it compromises yr outer leaf.

i've got a little less than 10 g's in my self-built studio. something to think about. or steal the garage for drum days. :twisted:
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Post by rhythm ranch » Mon Aug 11, 2014 10:36 pm

OSB = Oriented Strand Board

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Post by MoreSpaceEcho » Wed Aug 13, 2014 6:12 pm

floid wrote: the A-braces are structural. if they're run every other rafter, you'll need to come back with the remainder and use this plane for your ceiling. you can't insulate all the way to the ridge w/o compromising yr venting.
what does come back with the remainder mean? he needs to add braces to every other rafter and attach the ceiling to the braces?

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Post by floid » Wed Aug 13, 2014 7:12 pm

it's common to run a-braces between every other pair of rafters. 4' centers won't be enough to keep drywall from sagging tho, so every pair will need them. the a-braces now double as ceiling joists, and this ceiling forms a new attic space to be vented.

you also need to check that the a-braces are on plane, unless you want a wonky ceiling. confirm that the furthest brace on each end is level. then nail a 2x4 block to each end of each of these braces, close to where they hit the rafter. run a tight string from block to block on each side of the roof. use another 2x4 block as a gauge, checking that each brace is the same height above the string. it may be necessary to fir some down, tacking additional lumber to the side of braces that are too high. you might need a thicker gauge if the end braces are themselves too high - if braces in the middle touch the string. use 5/8 drywall.

hope that makes sense.
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Post by floid » Wed Aug 13, 2014 7:31 pm

before doing all that, you might just set up a stepladder on one end of the room and sight along the braces to see how on-plane they look.
:)

another thing: vinyl or plywood soffit? viynl will leak significantly more sound.
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Post by allbaldo » Thu Aug 14, 2014 9:20 pm

They're slightly wonky, for sure, so I figure I'll be adjusting in some way.

Do you think that if I'm going to end up not using 2 layers of sheetrock, that there's any point in using resilient channel?

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Post by floid » Fri Aug 15, 2014 4:12 am

RC will still decouple your drywall from your framing. And it should be possible to incorporate the hangers into your firring scheme.
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Post by Waltz Mastering » Fri Aug 15, 2014 7:01 am

I designed a friends attic mix room and ran 1x stringers to support 4" rockwool between joist with 16" centers that still left room for an air gap/ventilation between the abortion and roof. This worked really well for sound. I wouldn't bother with the sheetrock unless you want it finished for re-sale, .. but you can always add that or cover later. 2' between joist might be a little wide without some extra support.

Most likely you'll need to re-enforce the floor joist or/and double layer the 3/4" sheets depending on how much gear and foot traffic you'll have.

Air flow, cooling and heating will have to be taken care of. gl

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