walls for the poor!! - your comments appreciated.

[Johnrg]

This is cost and ease of construction motivated:

I am weighing up the options of the following between by control room and drum room.

Any comments on which to recommend as space/money saver, verse transmissin loss and overall STC (remember - drum room)

note: no windows in either wall.

wall one: (192mm total width)
2x6 framing filled with insulation and double 13mm plasterboard each side built totally on the edge of the drum rooms floating floor, one door - This wall will not touch the control rooms existing floor and will be play-matted to the shared ceiling and sealed properlly.


wall two: (252mm total width)
one 2x4 stud wall on the drum rooms floating floor with insulation and double 13mm plasterboard- playmatted and sealed to shared ceiling.
one 2x4 stud wall on the control room floor with insulation and double 13mm plasterboard, two doors - playmatted and sealed to the shared ceiling.
20mm gap between walls

Space, ease of construction and cost are my motivators here.
With the first system I will get another 60mm in my drum room but lose some mass-air-mass of the double wall.

I am thinking on paper version two is better, but will version one provide an adequate drum stopper, that is easier to build and alot cheaper.

your commets are appreciated.

JG

[AVare]

Space, ease of construction and cost are my motivators here.
With the first system I will get another 60mm in my drum room but lose some mass-air-mass of the double wall.

Good news: you answered your own question. The first one is better in the criteria you mentioned. The second one will give better isoaltion at low frequencies.

The "shared ceiling" concerns me. that may end up being your weak link.

Isolationist
Andre

[Johnrg]

Thanks for the reply.

The existing ceiling in the drum room is going to get another layer of 15mm plasterboard - It has one layer already with insulation

I am really limited on height and just can't afford to float the floor and install a false ceiling - it will be bad for my back!!

I am hoping the rubber strip between the walls and ceiling will help any flanking noise from the walls/floor into the ceiling and the ceilings double layer of plasterboard with insulation will be enough to insulate the drums going into the ceiling space and back into the control room / outside world. If not I can add a RC and more plasterboard to this ceiling after the fact as a last resort in the drum room after initial tests are done.

Think I will go for wall two (double stud) -

I suppose in this case two wrongs can't make a right. At least with decent internal walls between the rooms the ceiling problem - if any - maybe slightly reduced.

[AVare]

I am hoping the rubber strip between the walls and ceiling will help any flanking noise from the walls/floor into the ceiling and the ceilings double layer of plasterboard with insulation will be enough to insulate the drums going into the ceiling space and back into the control room / outside world

My concern is sound vibrating the ceiling in the studio room and being transfered right through the ceiling to the control room. The walls would not make a difference on that if the "shared ceiling" is one continuous piece.

I hope that explians my remark about the ceiling.

Andre

[Johnrg]

Totally understand - It is also a concern of mine!!

Hopefully it's not to bad - my ceiling height will be 7.6feet once finshed this way but only 7.3feet if I include a new false ceiling attahed to my floating wall/floor.

I still need the place to be kinda nice to work in!!

JG

[AVare]

Totally understand - It is also a concern of mine!!

Hopefully it's not to bad - my ceiling height will be 7.6feet once finshed this way but only 7.3feet if I include a new false ceiling attahed to my floating wall/floor.

I still need the place to be kinda nice to work in!!

JG

Straight question and please give a clear straight answer. No vague generalities.

What is the construction of the ceiling?

Andre

[Johnrg]

Hi ,
the ceiling is 2x4 roof trusses with one layer of 13mm plasterboard attached to the bottom and roofing iron attached to the top.
The ceiling cavity between the plasterboard and the trusses is stuffed with fiberglass batts insulation.
I am going to glue and screw another 15mm plasterboard to this existing plasterboard (just in the drum room) and when I raise the walls I will put playmatt and caulk on the top plate to provide a tight seal when it touches this ceiling.
This idea came from "Silva Productions" on the "studio's under construction" part of this site. The owner/builder sent me an email and explained the process and said the isolation was incredible.(photo attached of what I was going to do).
I am also building in side out walls around the exterior, but a normal double stud wall between the two rooms.
Thanks again - hope this is enough info.
JG

[AVare]

Good news, maybe. The ceiling as described it is the "weakest link" for total sound isolation. IT controls how effective anything else will be in teh big picture. We now have the design factor to work with. No sense building greater TL than what the ceiling will do.

Better;
Andre

[Johnrg]

So, bearing in mind I have a correctlly built floating floor, with correctly built double and inside out walls what do you recomend I do with the ceiling that will (a) not effect the height to much and (b) increase the rooms isolation at this weak link.

(1) How about a RC. So the ceiling would be 13mm plasterboard (original ceiling) - RC - 15mm plasterboard

(2) How about another layer of plasterboard - 13mm (original ceiling) / 15mm / 15mm (staring to think this maybe getting to heavy for the roof trusses.

Any help appreciated

JG

[knightfly]

Is that a photo of YOUR construction, or is it of Silva's - I'm not clear from your description -

Also, is this what you're describing as your roof situation, more or less? Steve

[Johnrg]

Hi Steve,

(1)That's Silva's photo - just used as an example of the playmatt on top of the inside out walls meeting the ceiling Gypsm board.
I got my original ceiling idea from this photo when I noticed that he only used one 5/8 board on the ceiling. I thought if I used two boards glued and screwed without the RC I would be OK.

(2) Your drawing is perfect, the only difference is that the ceiling has 100mm insulation in it resting on the Gypsm board (fibreglass ceiling batts)
Thanks
JohnG

[knightfly]

OK, next step -

Do your trusses run the long way or the short way (6 meters or 5 meters)

Is the existing 13mm wallboard on the ceiling continuous from wall to wall, or is it two separate sections separated by your inner wall?

You REALLY need to read (or re-read) the first few pages of the Complete Section thread located in the Reference Section of the Construction Forum; I can tell, because you asked about putting RC on your existing ceiling and then adding more wallboard.

From what I can see so far, it's going to be really tricky to get very good isolation from inside to outside with this; your roof (attic) area needs to stay vented, or things will rot up there; so that iron outer cladding can't be the outer leaf in a mass-air-mass system, because that would require hermetic sealing between the inner leaf (your existing wallboard) and the outer leaf. Doing that will bring you no END of grief from moisture/mold/rot. Ventilation is a necessity for maintaining a dry condition - without air circulation, the warm interior of the room will drive moisture from the room through the ceiling and into the attic, where it MUST have an escape path or things will get really ugly.

Next problem is getting decent isolation without massive weight; this requires that you have two separated leaves of mass on EVERY side of you, including the ceiling. The more mass, the better the isolation. The wider the gap between those masses, the better the isolation.

Your trusses, if made of 2x4's with only a 5 or 6 meter span, should support at least 3-4 layers of normal wallboard - there are a couple of tricky things about doing this though (not including the cost, I understand gypsum isn't as cheap in most parts of the world as it is here)

Where these layers should go is ABOVE and BELOW your horizontal chord (the level 2x4 of your truss) - below is relatively easy, because there's nothing in the way - however, even this may be a problem (more later)

Above the horizontal chord, you have the angled chords that make these into trusses - the "W" as some call it. If you were to install two layers of gypsum ABOVE the horizontals, the "W" boards would penetrate through these layers; even proper sealing around these joints won't stop the fact that you still have a solid board extending from the horizontal chord up through your upper wallboard and fastening to the rafter, which fastens to the iron, which can then radiate any and all sound that reaches it through this path. Still, this will be necessary for any decent isolation.

For that reason, I need to know what (if any) access you have to the space ABOVE your horizontal chords (where the insulation is now)

Below the horizontal chords, you could have an unbroken leaf (two layers) of gypsum; however, doing this would limit your isolation between the CR and live room due to flanking through that continuous wallboard between rooms; the way around that is to run your wall framing up almost to the roof frame, then do SEPARATE inner ceiling layers on EACH SIDE of that wall - the wall frames themselves would need to be resiliently sway braced at their tops, and all wallboard layers hermetically caulked. This would help isolation between rooms. (This is the solution to the problem referred to above under "more later". )

This approach would still leave you with marginal isolation to the outside, due to the flanking mentioned from the "W" boards of the trusses. The way around that would be to use RC for your inside wallboard layers on the ceiling, in order to decouple the inner leaf from the outer leaf; you may also need to do this for the walls, we've not covered much there yet.

If you want good isolation on your walls, you need to forget using "inside out" walls, or at least leave a WIDE air space between inner and outer leaves of mass; basically, a ceiling is just a horizontal wall, so most of my comments on mass and air space, etc, apply here as well. You could, however, put up "inside out" walls for the SOLE PURPOSE of saving on framing lumber; you would still need to use a complete insulation fill inside the walls, and the "inside out" method would only make it so you need only ONE set of studs; between which your acoustic treatment insulation can go, covered by cloth/slats/panels, etc - these would do double duty by also holding your wallboard layers for the inner leaf.

These inner walls need to be decoupled from the outer walls to maximise the isolation; some type of resilient sway braces will be needed here, as well as for the tops of the CR/Live room wall frames.

I've not even touched on your typical climate, heating/cooling days, humidity, etc; this will affect where (and what kind of) air/vapor/moisture barrier material that will need to be done.

Please re-read the "complete section" I referred to earlier, this will explain more on the isolation methods. I also need to know what/where/how many vents are in your roof as it is now; if there are soffits under the eaves that's one location for screened holes, etc - another is sometimes at the outer end of the rafter bays; a third is louvers near the end peaks of the roof; a fourth is what's sometimes called a "turtle" - a baffled sheet metal vent that's cut into the roof surface itself. We need a complete tally of these to better understand how your roof will ventilate.

Gotta run; study hard and look closely at everything I mentioned. There is no such thing as an un-important detail... Steve

[Johnrg]

Thanks Steve,

Will get reading and come back to you.

To answer your question on access however, the ceiling has what we call here "hip" trusses (they run down to all four sides of the building from the middle) and there is no access at all to the attic space - even if there was there is very little room to move in the attic due to truss construction.

Any system we come up with needs to be applied with the existing ceiling in place.

It maybe easier just to run new 70mm joists from the top of new walls across the drum room - (it's only a short span) and then add new plasterboard sheets to these new joists. That way I will somewhat fix the flanking noise because the new ceiling will be floating with the rest of the room and I will create a better mass - air - mass(existing plasterboard) - downside I lose another 85mm of height but it sounds like it will be easier and cheaper as lumber is cheap for me (I am a marketing manager for a sawmilling company!!)

Anyways, I will get reading and revert back.

Thanks

JG

[Johnrg]

Hi all,

Well I read through the stickies and Steve's excellent post above and have come up with the following for my ceiling as a idea using all my reading and the fact there is no access at all to the attic and I need to preserve as much ceiling height as possible.

(1) Build walls on the floor with playmatt on the top so that when I stand them they will provide a nice seal to the existing plasterboard ceiling. The playmatt decouple walls from existing ceiling.

(2) attach RC to existing ceiling and run two new layers of wallboard sealing all edges around new walls.

(3) build other side of the double wall between control room and drum room on existing floor (not new floated floor) and also playmatt the top for tight seal to existing sealing.

How does that all look? Any other things I could improve on?.

I am thinking I will get some seperation from walls and existing ceiling with the playmatt. I will also get some seperation from the existing ceiling and the new ceiling with the RC (kinda mass air mass)

see bad bad drawing!!

[knightfly]

Using two layers of gyp with only RC between them, even with insulation, will give you a resonance around 200-250 hZ; EXACTLY where you do NOT want it if you're trying to keep your Tom fills to yourself - you need to figure out a wider air gap and one more layer of gypsum on each side of that gap.

Also, you never mentioned; is your hip roof VENTED, and how (or why not)? Steve