Double-wall; Cable Routing; Ceiling Options query

[mi1ad]

Hi all,

This is my first post because most of my queries have always been addressed in other posts here! However, I have a couple of questions I couldn't find answers to here so if you could kindly advise on solutions or point me to relevant post I would be grateful.


Quick overview: I'm currently designing a small studio (approximately 8mx8mx2.4m) with a control room, a small ISO booth, and another room to be used as a second booth and/or CR. It's on the first floor of a two storey building with offices on the ground floor (studio directly above reception area). I'm raising the floor (using 2x3s on U-Boats, Rockwool, covered by plywood and acoustic floor boards), and building rooms in the room using double studded wall.


Q1) Does anything need to hold in place the Rockwool slabs in between the joists of the separating wall running alongside the existing exterior wall? Or will they hold with friction? Would it be okay to use another plasterboard or will this be considered a third leaf and affect the air gap in between?

Q2) What are the best methods of routing power supply, audio and data cables in between the rooms without jeopardising the sound proofing on walls, floors and ceiling? What are the pros and cons of doing it from under the floor boards, from the ceiling or through the walls?

Q3) Is using 2x3s for all joists and stud work okay? And how much gap between the walls should I consider (currently just 3cm) considering the size of the space.

Q4) The current ceiling has a hanging ceiling with t-bars and tiles with about 20cm gap. Shall I get rid of it and create new or use existing and fill with insulation? (only roof above)


I am attaching a draft plan for reference - I'm sure there are many other issues with the design so every guidance note will be much appreciated.


Thanks,

Milad

[Soundman2020]

Hi Milad. Please read the forum rules for posting (click here). You seem to be missing a couple of things!

Quick answers:

Q1) Does anything need to hold in place the Rockwool slabs in between the joists of the separating wall running alongside the existing exterior wall?

Not sure I understand the question: walls do not have joists: ceilings and floors have joists, but walls don't.

Q2) What are the best methods of routing power supply, audio and data cables in between the rooms without jeopardising the sound proofing on walls, floors and ceiling?

The general rule is one single penetration per room for the main power feed, and then distribute all the electrical from that point using surface mount system. Ditto for all signal wiring: one single point in each room. The actual penetration is best done with conduit that is decoupled inside the wall, between the two leaves.

What are the pros and cons of doing it from under the floor boards, from the ceiling or through the walls?

There should not be any "floor boards" in a studio! The floor needs to be solid, hard, rigid, thick, massive, and hermetically sealed. You can't get that with floor boards on joists.

The general rule of thumb is to run all electrical work high up inside the room, near the ceiling, and all signals low down, near the floor. Or vice versa. If they have to cross each other, only at right angles.

Q3) Is using 2x3s for all joists and stud work okay?

If your building code allows it, and your inspector is OK with it, then yes. But only for the walls: 2x3 for the ceiling won't span any useful distances with the amount of mass you need for good isolation.

And how much gap between the walls should I consider (currently just 3cm) considering the size of the space.

Air ap has nothing at all to do with the room size. It is only related to the amount of isolation you need (in decibels) and the frequencies you need it for. The gap size is calculated as a function of the MSM resonant frequency and the amount of mass that you plan to put on each leaf of your wall. A 3cm air gap is impossible, unless you are building both leaves inside-out, or building an inside-out stud wall close to a concrete or brick wall, which does not seem to be the case here. since the depth of a 2x34 stud is about 9 cm, The minimum possible gap for conventional construction is about 10 cm for a stud wall next to a concrete or brick wall, or about 19cm for a pair of stud frames with a 1cm gap between them. Even if you could get a 3cm air gap, that is way, way too think to be useful: the MSM resonant frequency would be very much too high to be useful, or you'd need to put so much mass on each leaf as to make construction impractical.

Q4) The current ceiling has a hanging ceiling with t-bars and tiles with about 20cm gap. Shall I get rid of it and create new or use existing and fill with insulation? (only roof above)

That sounds like a typical drop ceiling, which is pretty useless for studios. So yes, get rid of it, and build your new inner-leaf ceiling on top of your new inner-leaf walls, in the normal manner. And yes, in that case you would need to fill the cavity between those two leaves with suitable insulation.

guidance note will be much appreciated.

You don't need to splay the entire side walls of the control room: you can just splay the front part of the wall, and leave the rear part parallel. Much better use of space.

Also, I noticed u-boats and a very thin, flexible, light-weight floor system: That won't work at all. That's an attempt to float a floor, but that's not the correct way to do it. For the reasons explained in this link: http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173


Also, you are only showing one of the doors on each doorway: you should show both of them, for clarity. For example, the doors to your iso booth will not work, since the one that opens into the control room will be hitting the desk, and the outer-leaf door to the LR (not shown) will be clashing with the outer-leaf door to the vocal booth (shown). The main door into the CR is also in the corner, where it will interfere with the area normally needed for effective bass trapping. so I'd suggest re-thinking your doors, and making sure to add both of them to each doorway.



- Stuart -