Basement studio-room project in Boston area

[Luftweg]

Hi to all:

Been lurking for a few days on this forum, reading past posts (and the ‘stickies’ and reference sections).
Just registered last nite, and am now posting about my proposed project.

(to try to save time, I’ve tried to ‘bullet’ stuff as much as I could).

Geographic region:
- MA, on North Shore of Boston.
Community:
- Suburban, residential, family.
- Privately-owned

Proposed studio/room location:
- Basement
- Exact location within basement has some flexibility
- Project start date: started! (Construction imminent)

Main existing building:
- one-story ranch house
- full basement
- NG forced-air furnace, NG water heater, full laundry (gas & electric) in basement
- Poured concrete basement floor and walls (full-height to sills)
- Wooden-framed (softwood) upper-level; hardwood (red oak) floors; sheet-rocked walls and ceilings
- 10,000 ft2 lot size; 1500 ft2 living space (excluding basement)
- Ca. 1959-60 construction date

Studio/room proposed purposes:
- (mainly) acoustic & low-level electric instrument rehearsal and recording
- Vocal rehearsal and recording
- Rarely, if ever: drum kits, or large amplifiers.
- Home theater and entertainment
- 90 db, presumed maximum SPL (Occasionally 100 db? How loud can I sing without amplification?)
- when not recording or rehearsing (majority of time), isolation of room NOT required (doors/windows can open for ventilation)
- NEED to be isolated from floor above when I sing (yes, it's that bad, lol); that is, I don't want anybody in the room above to hear me

Basement specs:
- Height (from poured concrete floor to bottom of joists): 7’3”
- Poured concrete walls extend from floor to sills
- 6 x 8 center beam, with filled steel columns spaced every 8 feet along beam.
- Joists (above): 2 x 8; 16” OC; 12 foot spans from sills to center beam; crossed bracing straps
- Sub-floor (above): 1 x 8 planks
- Dry (no uncontrolled water issues (2 sumps)); dehumidified
- Very cool, even in summers (most of basement is well below grade)

Basic proposed studio/room specs:
Dimensions:
- Floor: 14’ x 20’ (approximate outside); 12’6” x 18’6” (approximate inside)
- Ceiling: 6’ 8” (approximate inside; one area 6’ 2”, to accommodate heating ducts) –
- 2 sides of studio/room to be directly along poured concrete basement wall; the other 2 sides adjacent to the remaining space of basement (one wall has an outer adjacent, unattached stair case leading to the main floor)
- One entrance way (to main basement, 5 feet from outside basement entrance)
- 2 windowed areas, along one concrete wall, facing outside ( approximately 17 by 32 inches, spaced 10 feet apart)

Construction:
- Wooden-framed, double-walls, double-ceilings; 2-layers 5/8” sheet-rock (or 3 layers ½” Durock) per leaf (this may depend on location)
- Double-walls, even along the concrete (including outer leaf sheet-rock, approximately one to two inches from poured concrete wall)
- (2) 2 x 3 parallel base plates, spaced 1” apart
- 2 x 4 studs, 16” OC
- 2 x 3 top plates (inner top plate height lower to accommodate inner ceiling)
- 4 trusses: 2 resting on outer wall top plate; 2 resting on inner wall top plate , bisecting length of room, 2 on each side of main heating duct; longest span 13 feet
- Each truss constructed from 2 parallel (horizontal on edges) 2 x 6 ‘s (or 2 x 4 ‘s ?), separated by short pieces (about 9 inches) of 2 x 4 studs, all secured (somehow) with metal bracing
- 2 x 4 (or 2 x 6) outer ceiling joists; longest span 11 feet (on one side of ducts)
- 2 x 3 inner ceiling joist; longest span 10 feet
- Floor to remain concrete (may be painted?)
- Double, isolated, solid, entrance doors (both standard width, but different heights); one attached to inner wall, one attached to outer wall
- Double (opening) windows; 12 inches between each window pane; multi-layer (4?) sheet-rock for window soffits (but leaving one or one-half inch gap between wall leaves.
- Fiberglass insulation between wall and ceiling leaves, and between outer ceiling joists and main floor joists
- Electrical supply would be fed via long, doubled-back, isolated conduit; all lighting and wiring will be surface-mount via conduit, surface boxes, table fixtures, or track lighting (or maybe plug-mold)
Misc.:
- Furnace, water heater, meters, TV cable, water supply or lines, laundry, electrical panel, and outside door, are NOT near proposed studio/room location
- Telephone service cable is in corner, above proposed location; will be conduit-ed along sill past the studio/room
- A main furnace duct runs below existing joists, and above proposed location, nearly bisecting it.
- 2 between-joist, heating ducts are above proposed space, each beginning above main duct and ending on opposite walls
- Nothing is below concrete floor for except solid earth (therefore no treatment?)

Concerns and (some) potential problems:
Spans of ceiling joists:
- 2 x 4, or 2 x 6 (?) ; no ‘extra’ room for 2 x 6 joists (especially inner ceiling joists)
- If joists are of oak, maple, yellow pine, metal, etc., could 2 x 4 joists be sufficient?
- If joist spacing is decreased, could 2 x 4 joists be sufficient?
- Conflicting numbers from span ‘calculators’
- Is ‘live load’ of any consideration?
- Does ‘dead load’ include joist weight also (not just external load)? Why?
Floor:
- Any problem leaving floor concrete exposed, since only solid earth is below it?
Windows:
- Is leaving existing basement window and glass (thin) a possibility?
- Thickness of inner window?
- Should I double-leaf the soffits or leave them ‘open’ to the leaf space?
Leaf spacing:
- How much of a compromise is the decreased leaf spacing of the ceiling or of the areas surrounding ducts?
- Will putting an outside wall within 2 inches of concrete wall constitute an additional leaf, or otherwise be a compromise (even if there is no ‘seal’ between the sheet-rock and concrete)?

Other thoughts:
The ‘adding extra leaf’ concept:
- From looking at all the pictures of how adding extra inner leaves decreases performance, I noticed that none of these leaves pictured a ‘free-floating’ extra leaf; indeed, all of the permutations had sheet-rock affixed to the studs which supported the 2 original leaves; having the sheet-rock attached to the same studs itself could probably a big factor in the performance decrease.
- I’m wondering: if the total space between the original leaves remained the same, and if the extra leaf was not attached to the either original leaves, what would the performance be (not that I’m even considering doing it). Of course, this additional leaf must isolate both compartments, otherwise wouldn’t it really then be just a ‘baffle’?
Span calculators:
- I had always understood that most hardwoods, such as oak, maple, birch, etc. (and even some softwoods), had greater strength than spruce, balsam, or pine; why does that linked span calculator (from several posts on this forum) actually end up DECREASING the maximum allowable span when one changes from, for example, spruce to white oak or maple? Is it more of a deflection issue than of strength? For me, it is counterintuitive.
- I found at least 2 span charts that list an apparently higher maximum span for the same input criteria, than does that span calculator – I don’t understand why this is so (other than the possibility of different regional regulations being used).

thanx,
Kenni

PICTURE DESCRIPTIONS:
(NOTE THAT ALL STUDS AND INSULATION SEEN ARE FROM OLD CONSTRUCTION AND WILL BE TORN DOWN)

FIRST PICTURE:
Shows the 2 biggest ‘meanies’, the 6 x 8 center-beam and the main heating duct (drops 10 inches from floor joists).
On the concrete walls is OLD construction that will be torn down shortly.
Above the beam are 2 x 8 floor joists, and really not much room to put in 2 x 6 isolated ceiling joists (for the outer leaf), so I’m scrambling to find an alternative (possibly ‘sistering’ smaller metal or wood 2 x 4’s to gain span strength).

SECOND PICTURE:
Here is view of the top of the existing concrete wall and floor joists.
Top of the concrete is only 3 ½ inches from the bottom of the floor joists.
Top plate and studs you see are OLD work and will be removed.
NEW top plates for the outer leaf of the wall will be in approximately same position, although 1 inch below the floor joists (and not attached).
Note that the door will not be within the studio/room; the communicating double doors to the studio/room will be about 4 feet opposite this door.

THIRD PICTURE:
Another shot of the floor joists near a concrete wall.
The white telephone line is an approximately the same position as the outer leaf top plate would be.
Note the OLD work studs (attached directly to the floor joists!) and insulation, that will be removed before new construction begins.

FOURTH PICTURE:
Cross-bracing between the 2 x 8 floor joists.
The big reasons I would like to avoid using 2 x 6’s as outer ceiling joists between them are these braces, the 2 between joist-heating ducts, and that the bottom of the floor joists is just 7’3” from the concrete floor.

FIFTH PICTURE:
Here is a wider shot of the 6 x 8 beam, the main heating duct, the two between-joist heating ducts, the steel post, and the 2 x 8 floor joists.
Note the OLD work strapping, which will soon be removed (as will the old studs and insulation).

SIXTH PICTURE:
Closer view of the pole, the beam, the main duct, the between-joist ducts, and the 2 x 8 floor joists.
The beam and main duct will be ‘ducked’ by both leaves of the ceiling.
I’m planning on building trusses that bridge between the walls (4 trusses total).
These would be placed on both sides of the beam and main duct area (2 on each side), and would be used as support for each of the ceiling leaf’s joists.
The steel pole will be also enclosed within double-walling, and this will be used as center-support for the trusses (all isolated, of course).


****
I will be taking pics of my floor plans and detail diagrams for construction ideas.
I will also be posting more pics of other things, like where the stair case is, etc.

PLEASE FEEL FREE TO MAKE ANY COMMENTS. PLEASE PLEASE.

[Luftweg]

Below is a drawing of the cross-section of what the walls along the concrete might look like.

It shows a few things that are causing me questions:

1.) Third leaf?
There would be an UN-ISOLATED air gap between the outer stud wall sheet-rock and the concrete wall.
a.) Would this constitute a third leaf even if it is open to the rest of the basement (it is not sealed off, and air can travel between it and the entire basement)?
b.) Would it be better to incorporate the poured concrete walls AS the outer leaf? If that is true, it would seem a difficult matter of sealing the other outer walls to the concrete (what I mean is that the intersecting new walls need to seal against the concrete, AND there would still be a small gap ABOVE the concrete wall that needs to be sealed-off).

2.) Depth of ceiling joists?
I would really prefer to juse something close to 4 inch depth, than to use 6 inches, because I don't have lots of room between the existing floor joists, AND I can't really afford to lose any ceiling height in the proposed room.
a.) Isn't it possible to sister two wooden or steel 2 x 4's together and gain maximum span strength? I do have room to spare for that.
b.) What would be better to use wood or steel? If wood, is it possible to use a stronger wood, say oak or maple, and gain maximum span strength that way?

It would seem to me that if 2 steel studs were boxed together considerable strength could be gained:
(The following is a link of Steel Stud Manufacturers Association Technical Information; there are diagrams showing how to 'stiffen' a stud or joist by boxing or back-to-back joining of 2 members; page 42 gives span specs)
http://www.rinker.com/steelcon/download ... mation.pdf

*** UPDATE: I no longer plan to do the ceiling or walls like this, as it is obviously triple-leaf; see later posts ***

[kendale]

Aloha and welcome to the forum, Kenni

Congrats on your studio build! Great intro and info provided. Please don't be discouraged if there hasn't been any responses yet. Some of the questions/issues of your build require more knowledge/experience than most of us have, and Steve/Knightfly (our senior moderator) has an incredible work schedule/work load with his regular job before having the chance to respond to some of the posts. So hang in there.

In the meantime, looking forward to your floorplan and build!

Aloha

[Luftweg]

thanx Kendale.....

At least I will not have to contend with a volcano or any earthquakes (or hurricanes, for the most part).

I realize that I have to supply more detail diagrams and a floor plan, plus some more pics that will give the people 'who know' more to go on (and an easier time at it too).

For now, does anyone know how an outer leaf should be done when it would be sitting right next to a poured concrete wall (within 2 inches)?
I'm not the least bit worried with transmission THROUGH the concrete wall (as it IS poured concrete), and there is only the outdoor earth behind it (up to 2/3 or more of the wall height), and there are NO neighbors in close proximity, then I could better 'finalize' my plans.

So I'm thinking that incorporating the concrete wall INTO the outer leaf should be okay; however, this might make it difficult to a seal with the other walls.
On the other hand, building a stud wall next to the concrete (within 2 inches, but NOT sealing-in an additional leaf) would make it easier to get good seal with the other walls.
I just don't know enough about whether that would create a 'quasi-leaf'.

If I could only get answers to this question, and the one about sistering joists in order to be able to use shorter joist heights (2 x 4 versus 2 x6).....

K

[kendale]

Aloha Kenni,

does anyone know how an outer leaf should be done when it would be sitting right next to a poured concrete wall (within 2 inches)?

Have you considered using John's inside out design?

Aloha

[Luftweg]

Aloha Kenni,

does anyone know how an outer leaf should be done when it would be sitting right next to a poured concrete wall (within 2 inches)?

Have you considered using John's inside out design?

Aloha

Hi Kendale:
Hmmm, interesting.... although there are a couple of things that I don't want or can't do.
I don't plan on floating any floor at all; just keeping the plain concrete floor (of course I will seal it with appropriate paint, and throw some sort of carpeting over).
One big reason is that I don't have the ceiling height to 'lose'.
Another thing is that I will not be having any drum kits or large bassy amplifiers in the room (thus not a large amount of 'impact' sound transmission).
And there is nothing but solid poured concrete and earth below it, so I'm 'assuming' that very little transmission of sound will occur through the floor (and much rather would worry about the walls and ceiling).

One other thing I see in that design diagram is the 'resonator'; is that used as a bass sink?
Finally I would not know how to address the upper part of the wall -- that is, the 3.5 inches between the top of the concrete wall and the (above floor) floor joists; I need a really good double-wall treatment (mass-air-mass) for that part.

I will have to examine that design a few more times until I 'get it'.
Maybe I can find the links for the posts so I can understand it better.

thanx,
K

[Luftweg]

I hope the following picture explains what I plan to do in order to double-leaf the ceiling.

Again, since the above floor and floor joist don't touch the proposed outer leaf, and since there is free flow of air movement over that leaf, I'm thinking that this would be okay.

I don't know enough about whether -- in some way -- that above floor and floor joists would constitute a 'true' leaf.
Any thoughts anyone?

thanx,
K

*** UPDATE: I no longer plan to do the walls and ceiling like the below pic, as this is too 'third-leafy', as well as excessive; see later posts for 'new' ideas ***

[guitardad72]

Luftweg,

Welcome to the forum, I had read your comments on another thread and meant to post here sooner but... I saw the length of your 1st post... and good job man. It takes some of us a while to read through things, once we get the time.

OK so your ceiling pic is definatly a 3 leaf wall, hands down.

Andy is currently dealing with his ceiling near the end of his thread:

http://www.johnlsayers.com/phpBB2/viewt ... &start=210

Basically you'll want to add cut up peices of drywall in between the ceiling joists and use cleats to hold them up against the ceiling/floor. Something like near the end of this page:

http://www.saecollege.de/reference_mate ... /Walls.htm

BUT you will have to figure out the load weight of your existing ceiling/floor joists before you make any plan. Green Glue although expensive can make 2 layers of drywall almost equal to 4 layers, and makes good cents on ceilings where load is critical.

I keep on refering in posts to Rod's Book in the stickies.... he has pages dedicated to this exact ceiling construction and how to do it correctly almost step by step.

Another factor with ceiling is if you have the height to use seperate inner room joists for the inner leaf of ceiling. From you pic I presume you have... again span/weight is important... wait ... no you don't at 7'3" slab to joist. Code for room height is 7'. Hmmm, I'm gonna stop on this topic for now.

How I wish I had solid concrete wall and not hollow Cinder Block for my own studio.

Your Concrete wall should (is) your outer leaf. Based on your sound isolation requirements I'm going to guess you'll want a 2x4 wall built 1" to 3" away from the concrete wall with 2 or 3 layers of 5/8" drywall on the inner leaf, inner side.

Your right on not needing the floated sub floor, expencive and easy to screw up.

The resontor wall and inside out wall in Kendales post from John.

Inside out walls are built on the ground, rasied into position to be squared, lowered back down and then drywall goes on. Then it has to be lifted back into place, and it would be really, really heavy. With all edges of the drywall not in reach you can not caulk it. Sound isolation is less with a inside out wall, although valuable space will be gained if using a slot wall inside the inside out wall.

The slot resonator shown would be a low-mid, mid absorber as well as a very good side wall diffuser and if built on side walls splayed will create a RFZ zone. A very useful acoustic tool, if built correctly. BUT even with all the "holes" a slot wall still creates triple leaf effect which must be taken into consideration. I am planning on putting one next to my exterior CB wall (cavities filled with sand), I'm still considering if I'll use another on a new 2x4 double (exterior) wall, and I'm definatley not using any slot wall where sound isolation is important.

BUT sometimes tripple leaf can't be avoided so it seems studio builders do there best to work around it.

And remember more mass or more air = more isolation. Inside out walls take away air and make mass on inner leaf a back breaker.

Marc

[sharward]

I just want to echo Marc's sentiments on the great job documenting the details in your introductory post, Luftweg. Awesome.

I'm afraid that's all I have time to do on it though... Life is crazy busy for me right now........ Getting ready to go to Hawaii next week, trying to pull forms off my concrete when time permits, treating an injured pet, rehearsing for a gig at the end of the month, and oh yeah, this thing they call employment now and then...

Please be patient...... I know your project construction is imminent, but you'd be wise to slow down, learn as much as you can, and wait for the feedback you'll need to proceed with confidence.

--Keith

(Sorry for the hit and run.)

[medo]

Perhapas you have gone too much in detail for the first post?
I have seen your post before I joined the forum and I didnt had the concetration to reed it all. I have read it last night, and its very well written, but from my point of view there is little I can gain from studying your case. ... That is, until you get some quality replies.
Maybe you could draw some more attention with a simpler post?
Anyway dont feel bad about it, it takes time and patience.
Hope your project turns out fine.
keep in touch, Medo

[sharward]

I have to disagree with the "too much detail" concept. There are so many threads on this forum where Steve and others have had to drag details out one post at a time. It's time consuming and frustrating for all parties.

I think we're just in one of those time periods where Steve and others (myself included) are just so busy that our ability to contribute is very limited. These are the times that we need to be especially patient, yet also not be somewhat assertive at times.

Please don't be discouraged and let's help reinforce the "give us lots of details up front" message that Steve sends regularly on this forum.

--Keith

[kendale]

Aloha,

I will have to examine that design a few more times until I 'get it'.
Maybe I can find the links for the posts so I can understand it better.

Sorry about that. Here's the link: http://www.saecollege.de/reference_material/index.html
(click on construction tab at left - walls and ceilings at top)

Aloha

[Luftweg]

Hi Guit-Dad:

thanx for the reply...

Luftweg,
.....
OK so your ceiling pic is definatly a 3 leaf wall, hands down.

Actually, although I definitely see that it could be considered a 'third leaf' because of where it lies, I'm not at all convinced (yet) that it is a TRUE third leaf.

As far as I'm currently being led to understand, a TRUE leaf is formed when an air space is sealed-in.
My original picture doesn't show that the ends (above the outer (2nd) leaf) are open to the rest of the basement; see the new picture below.

If there is no seal between the above floor joists or floor, then it is not quite the same thing as a TRUE leaf.
Remember, air can freely move around the the 2 leaf system, between the 'third leaf' floor and floor joists and circulate with the air in rest of the basement.
This would almost HAVE to have some effect.


**** I HAVE YET TO HEAR ANY EXACT DEFINITION OF, OR WHAT CONSTITUTES, A 'TRUE' LEAF, or what the effects would be on sound transmission if it were NOT a 'true' leaf (e.g., if it's not sealed-in, if the air gap is huge, etc) ****

If what you say IS true, and the above floor and joist constitutes a leaf, then ALL the walls -- including the ones where the concrete wall will be 15 to 25 feet away -- would also be three leaf walls.
The only real differences would be the proximity of the leaves, and the size of the air gap.

So, I hope I'm being understood when I repeat:
There must be limits to the 'third leaf effect', AND there must be an exact definition of what constitutes a TRUE third leaf.

I think alot of this is becoming like a 'taboo', or 'folklore'.
People see 3 things next to each other and automatically think 'three leaves'.
Sometimes that may be true, other times it may not, and still other times there might be a middle ground (my so-called 'quasi-third-leaf').

IF there is a middle ground, then one has to try to determine to what degree there is a third-leaf effect.
It may just be that if the 'third' leaf is NOT sealed-in, not physically connected, AND/OR is significantly far away, then other factors could become more dominating.

Again, a direct answer to the 'big' question remains to be answered.

Andy is currently dealing with his ceiling near the end of his thread:
http://www.johnlsayers.com/phpBB2/viewt ... &start=210

Thanx. I will take a look.

Basically you'll want to add cut up peices of drywall in between the ceiling joists and use cleats to hold them up against the ceiling/floor. Something like near the end of this page:
http://www.saecollege.de/reference_mate ... /Walls.htm

thanx, will take a look (think I've seen it before though).

BUT you will have to figure out the load weight of your existing ceiling/floor joists before you make any plan. Green Glue although expensive can make 2 layers of drywall almost equal to 4 layers, and makes good cents on ceilings where load is critical.
I keep on refering in posts to Rod's Book in the stickies.... he has pages dedicated to this exact ceiling construction and how to do it correctly almost step by step.

Another factor with ceiling is if you have the height to use seperate inner room joists for the inner leaf of ceiling. From you pic I presume you have... again span/weight is important... wait ... no you don't at 7'3" slab to joist. Code for room height is 7'. Hmmm, I'm gonna stop on this topic for now.

Yeah, that's alot of it; I don't have the luxury of the vertical space.
Where is it code that ceiling height for basements has to be 7 feet?
I think that would be for 'living' spaces, no?
I'm just wondering because we have a part of the basement where the ceiling height (height from basement floor to above floor joists) is less than 6'6".

Your Concrete wall should (is) your outer leaf. ...
Your right on not needing the floated sub floor, expencive and easy to screw up.

I agree that my concrete wall COULD be my outer leaf; it very easily could be the best sound-blocking item I got going for me!
It's too bad that I don't really need to block direct sound through the concrete (walls or floor) since there is nothing behind them except earth.
But it might block alot of indirect path-ing.

An issue I have with the concrete walls is that there's a space of 3.5 inches between top of the concrete wall and the above floor joists -- this area might be difficult to get a good seal.
It may also be hard to get a good seal between the outer leaf sheet-rock walls and the concrete.
However, it's well worth looking into.

Those were really the only reasons that I wanted to avoid directly using the concrete wall.

The resontor wall and inside out wall in Kendales post from John.
...... Sound isolation is less with a inside out wall, although valuable space will be gained if using a slot wall inside the inside out wall.
.... a slot wall still creates triple leaf effect which must be taken into consideration. ....
BUT sometimes tripple leaf can't be avoided so it seems studio builders do there best to work around it.

And remember more mass or more air = more isolation.

I have no real plans to use the slot wall or inside-out wall design, unless it somehow could be adapted for ceiling use in my situation -- to save vertical height.
But if the isolation is not too good, and the construction is more complicated, then it might be best avoided.

More mass and/or more air space = more isolation.
But there are other factors involved.

For instance, different densities seem to have an effect, even if the total mass of leaf remains the same (the effects appear to be related to specific frequency ranges).

And as I was saying above, air spaces depend on not just how thick they are, but also on other things like how well they are sealed.
This is really quite apparent when one thinks of speaker cabinet designs (particularly dealing with low-frequency or bass ranges);
when a cabinet is sealed, the throw of the bass driver is restricted somewhat, but when it is vented the driver is free to move air in and out of the space behind it (sometimes this can even cause a driver to destroy itself -- by travelling too far back and forth); it could even end up cancelling sound waves if any phasing inversely aligns.
This almost HAS to have an effect on any of the air spaces of any of the leaves of a studio wall.
In fact, we are constantly told that the leaves of a studio wall have to be sealed very very well, and that even small leaks can greatly compromise sound isolation (sound pressure tends to take the easiest path)
Why then, wouldn't the fact that a 'third' leaf NOT being sealed or touching AT ALL have an effect on sound transmission?
It could even be conceivable that it might largely mitigate the proximity (closeness) of the wall.

What we really need to truly answer this question is results of controlled studies that vary some parameters, while keeping others the same -- or in the very least see a paper or two written by acoustical engineers or physicists, addressing this and explaining what the effects should be.
Anything short of that would be speculation (although construction experience in similar situations might account for something).


PICTURE NOTE:
The term 'outside' refers to the rest of the air of the basement; there is NO dead air space; in a sense, the quasi-third leaf is 'ported', allowing high pressure pulses that make it through the 2nd (outer) leaf to dissipate to the entire air of the whole 'outside' basement -- that's a pretty damn big 'spring'.
Does the fairly close proximity of the 2nd (outer) leaf override any benefits of this free flowing of air?

*** UPDATE: I no longer plan to do the walls and ceiling as pictured below for several reason, not the least of which is the 'third-leaf' effects; see later posts ***

[sharward]

Where is it code that ceiling height for basements has to be 7 feet?
I think that would be for 'living' spaces, no?

Check with your local building department.

Note that they'll probably consider what you're doing to be converting your basement into living space (i.e., "habitable area"), so you will probably be held to those standards.

There are exceptions... A certain percentage may be allowed to be lower than 7 feet.

I've also sometimes heard 7' 6" is required.

Again, check with your local building department. There are many sets of building codes and many versions of those codes, so it all depends on which one your municipality has adopted.

--Keith

[Luftweg]

Hi

Well I've pretty much resolved that the concrete wall WILL be the outer leaf.

It's AT LEAST 12 inches thick of poured concrete (might even be 13 or 14 inches), with nothing but earth behind it for a minimum of 2/3 the height of the wall.

So the sound-stopping power should be better than any other member in the system.
It might even be true that a 2-leaf wall is not needed on the walls of the studio bordering the concrete (not very sure on that one).

Regarding the above floor joists and flooring:
I'm not convinced (yet) that they should be incorporated AS part of the outer leaf of the ceiling.

However, I have attached a pic showing what I'm supposing it would look like to have the above floor (and concrete wall) AS outer leaves.

There ARE some definitely known good points though.
It would:
1.) allow taller final ceiling
2.) reduce material costs
3.) reduce labor time

The big question remains whether sound control would be better with the floor incorporated into the outer leaf, or have it remain as an isolated quasi-leaf.

The potential 'mitigating' factors:
1.) loss of one isolation from a solid connection
2.) loss of free moving air between the outer leaf and the quasi-third leaf.

I'm fairly convinced that this is not a matter of simply removing a TRUE third leaf, for the reasons I have outlined in the previous post.

So, whether the loss of the free-flowing air space, and the loss of a solid connection isolation balances out against a loss of a quasi-third leaf is still pretty questionable in my mind.
Remember, this 'third' leaf is NOT sealing-in a dead air space -- it allows free flow of air around it (where any low frequency pulses might escape and dissipate into the larger part of the basement before transferring any energy to the above floor and joists?); this factor alone likely adds for some level of effect.

One other thing that I haven't really figured:
How would I then attach the top plate of the outer leaf?
Is it to be attached right to the above floor joists? (if so, then that would be a GAIN of a solid connection between the outer leaf of the studio wall and the upper floor! perhaps that's okay, but if there is still some energy vibrating in the outer leaf, then it would be transferred by conduction to the upper floor)
Maybe I could put something between the top plate and the joists that maintains the air seal between the leaves, but reduces transmission of vibrations?

thanx again,
K