SSDC1 Single Garage conversion in Maryland USA

[johnv]

Just northeast of the DC beltway

[johnv]

This part of the house is teh quietest.

Normal sound levels in the garage are around 48dB C
worst case is in teh music room where currently it is open to teh HVAC system which, when burners are running, is hitting 75dB or so C


A few concerns.
THe cielings I assume will have to be ripped, RISC channeled and restored,
they have fire suppression sprinkler heads scattered around and these will have to be 'dealt with'...?
The truss-joist things are part of my concern. Looking to get an structural person in to tell me what I can do up there, add layers of wallbaord or not.

I am obsessed with how to think about the PROCESS when we rip the wallboard off, add/modify walls, do ACpower install (subpanel and circuits for wall outlets and lighting) HVAC adds and such and then close it all back up. Making this as efficient as possible.

[johnv]

The intents here are for the control/voice room to be, first, a trustable monitoring room.
It's not large and that is a concern.
The isolation need there is to be able to do voice/narration work there without interference.

The music room is less critical both in isolation and overall room acoustics. The biggest thing there is the added wall with door to close it off from the hallway that has the HVAC roaring. A quick ballpark check with my phone dB meter (studio six digital) says this runs around 75dB at the hallway where the wall will go.

I have One thing that gets me into a cycle of in=for-a-penny-in-for-a-pound decision-block is once you start pulling drywall and ceilings down so you can get at electrical additions and HVAC elements, deciding what exactly makes sense to put back...

in the more critical control/voice room, since I'm going for isolation AND a trustable mixing playback sound,
with inside-out added walls , DO you bother to pull the drywall off, instal added eletrical, then put the drywall back on the original walls...
OR
do you just not take the original-wall drywall off in the first place, add the electrical on top of the original drywall in conduit, and bring that back in through the new inner walls?

Foot falls and movement noise from teh upstairs through the ceiling is a very real issue. That has to come down and have some reasonable isolation done. What happens with teh added thickness where the fire-sprinkler heads come through? is that something I have to farm out to a plumbing contractor?

[johnv]

Having never seen 2x4 truss floor joists I was concerned, but it seems that they are indeed a very good thing. Better is that I have very easy lateral routing access for duct, cable and such.

My thought at this point is that I ought to strip drywall from walls and ceiling in the mix room, trying to re-use the drywall re-installed against the back side of the walls as recommended for added mass.
This gets access to most of what I need to install the AC power , wiring and air duct work.
What goes back up though?
If I do inside-out wall construction, do I leave the original walls without surface drywall?
Since the inside-out design has a layer of absorption on the far side, does that mitigate the two-leaf-rule and can/should I put drywall back over the original walls as more mass?

Is it foolish to try and minimise what wall-removal work gets done in the music-room?

The full-bore answer of course is to strip ALL drywall and ceilings and have a blank slate. Looking at costs and down-time.
Making priorities amongst all this makes me respect general-contractors' project management skills!

[johnv]

a couple of concerns

the idea here is to take the long open garage area as it stands now and divide it into a shorter outer mini garage/work area on the outside, and the inner area beyond it becomes an editing/mixing/voice recording room between that and the existing back rec-room (music room) area.

There is a natural division point for this along the first of two lateral ceiling beams.
The second beam is already incorporated in the original wall construction between the back of the current full garage and the rec-room/music-room.
These beams are enclosed in drywall so I do not yet know what they are made of... another larger wood-truss joist, or a solid wood beam.

Just how to work with the new garage wall along that first beam is an unknown to me.
My first thought is to remove the drywall around it, build this new wall directly under it right up into it. Treat that like a 4th of the existing walls and then build inside out walls all teh way round.
This outer wall needs have the only door in and out of the studio room
needs to be strong for security,
solid on the outside as a workspace wall.
Likely has to meet some sort of fire-stop code (?)

the floor in the garage is concrete.
Then, beyond the first beam, the floor in what will be the new studio/control-room has an old layer of ~1" (?) plywood with another ~1/4" layer on top of it. This wood overlay does NOT extend all the way to the floor line directly under the beam, it's about 10" short of that.
Not sure WHY that wood layer is there, or whether to extend and use it as the main floor base, or to pull it up and stay with the concrete. Part of this thought goes with the idea that garage floors are an inch or so LOWER than the main house floor to accommodate and drain garage-car fluid spills. This would play into the current entrance door from the basement into the garage which is a small drop down in level. This would NOT change but the garage floor WILL have a step up to the studio-room door threshold.

Images
- the view from the outer roll-up garage door looking back at the garage and the first cross beam
- the view of the beam itself where it meets the wall by the garage door to the basement interior
- the view of the floor wood over concrete

[johnv]

Having learned that I have open truss-joists rather than solid wood ones in the ceiling, Does this change the approach to the usual ceiling design wherein you strip the existing ceiling drywall, maybe add a layer of drywall up against the underside of the upper-floor decking, then add insulation, then RISC clips and a new ceiling? Does the apparent fact that, unlike the solid wood joist, which seals things up on either side of the insulation, the truss is OPEN to the sides and so may create an wide, open ceiling area, instead of essentially long individually-sealed cells with the solid wood joists as sidewalls?

[johnv]

bump...?

[johnv]

re-bump...

[Soundman2020]

Wow! Your thread sure does seem to have slipped into a very quite place! Sorry about that!!!

they have fire suppression sprinkler heads scattered around and these will have to be 'dealt with'.

Do you have a plan for that figured out?

The intents here are for the control/voice room to be, first, a trustable monitoring room.

Have you taken a look at ITU BS.1116-3? That should be your guideline for the acoustics response of the room.

The biggest thing there is the added wall with door to close it off from the hallway that has the HVAC roaring. A quick ballpark check with my phone dB meter (studio six digital) says this runs around 75dB at the hallway where the wall will go.

What type of wall did you have in mid here? A typical house wall will get you roughly 30 dB of isolation, so your roaring monster will end up around 45 dB. Perhaps not silent enough? Are you planning to do a proper "room-in-a-room" build?

in the more critical control/voice room, since I'm going for isolation AND a trustable mixing playback sound,
with inside-out added walls , DO you bother to pull the drywall off, instal added eletrical, then put the drywall back on the original walls...
OR
do you just not take the original-wall drywall off in the first place, add the electrical on top of the original drywall in conduit, and bring that back in through the new inner walls?

Depends on what your goal is, and what your design concept is, as well as the existing construction, and also your budget....

Foot falls and movement noise from teh upstairs through the ceiling is a very real issue. That has to come down and have some reasonable isolation done.

Then it seems that you do need proper "room-in-a-room" construction.

My thought at this point is that I ought to strip drywall from walls and ceiling in the mix room, trying to re-use the drywall re-installed against the back side of the walls as recommended for added mass.

If I do inside-out wall construction, do I leave the original walls without surface drywall?

Yes, and that is regardless of whether you do inside-out walls or conventional walls. The issue is not how you build your inner leaf, but rather that it needs to be built as a single leaf, which when combined with the existing single leaf (studs with drywall only on one side) will give you the two-leaf system that you need.

Since the inside-out design has a layer of absorption on the far side, does that mitigate the two-leaf-rule and can/should I put drywall back over the original walls as more mass?

I'm not sure I understand the question: You ALWAYS need to put insulation in the wall cavity between your two leaves, regardless of how you build. It does not matter if you build the inner-leaf inside out wall or conventional, you still always need insulation in the cavity. The purpose of that insulation is to act as a damper on the resonances going on in the cavity, and that is always necessary. I'm not sure why you would think that putting insulation in the cavity would allow you to add an extra leaf. I don't follow the reasoning there at all.

The full-bore answer of course is to strip ALL drywall and ceilings and have a blank slate.

Yup!

Not sure WHY that wood layer is there, or whether to extend and use it as the main floor base, or to pull it up and stay with the concrete.

If that were my place, I'd pull up the OSB and save it for re-use in other places, and use the concrete slab as the studio floor.

Does this change the approach to the usual ceiling design wherein you strip the existing ceiling drywall, maybe add a layer of drywall up against the underside of the upper-floor decking, then add insulation, then RISC clips and a new ceiling?...

I would suggest that your best course of action here is to create a complete, accurate model of your current situation in SketchUp, then post it here so we can take a look at it. Then also do a second version that includes what your current plans for the inner leaf rooms, so we can see if it makes sense, and suggest ways of improving it.


- Stuart -