2x4 or 2x6

[guitarguy]

For walls is there any advantage to using 2x6 over 2x4 or vice versa.

Also, Would it be a bad idea to slant the ceiling in the Live room?

Here's a conceptual drawing of a layout we came up with of the room itself. It's a very old building (I base this on the remnants of wax coated wiring that I found). If you must laugh... 2 things it is an elementary drawing, and please tell me why your laughing. Dimensions are 37ft x 47ft the office space to the side is about 10ft x 24ft but will be sub-leased to a friend of our who does booking.

[knightfly]

Depends on what type wall construction whether 2x6 makes any difference, what did you have in mind; single stud, ditto with RC, staggered stud but single plate/cap, double framed... Generally, no it doesn't matter much, if at all. The actual air gap between leaves is the main thing.

You're expecting someone who once measured for door hinges with the door upside down to laugh at you? Not this week... Steve

[guitarguy]

Thanks for the reply Steve. I've just seen little literature with the use of 2x6's. Just wanted to make sure I wasn't missing anything, before I start to make any final decisions on my wall layout.

[dymaxian]

2x6s are used for structural walls most often- the exterior and load-bearing interior walls. For interior walls, 2x4s are fine. You'd gain a little more space between drywall panels with 2x6s. If you're going to be building rooms-within rooms, and your ceiling is bearing on the interior walls, you may want to build those walls from 2x6s depending on how big the ceiling joists are, how big the ceiling area is and how much stuff will be bearing on it, blah blah blah...

Rod Gervais can probably recommend better guidelines on how much 2x4s will support.

[knightfly]

2-story houses were built with 2x4 frames before insulation became the hot priority - you just put the first floor framing on 16" (or even 12" ) centers, no big deal. The only advantage to 2x6 framing would be some increase in wall stiffness - for best isolation, you want separate frames ANYWAY, so no reason to use wider than necessary studs. The one exception would be if building a medium performance wall using staggered 2x4 studs on plates and caps of 2x6, or perhaps a straight 2x6 stud frame using RC on one side, for increased air gap. Even that would be improved on by using separate steel stud frames - same air gap, better isolation.

So, no - not a lot of reasons come to mind for using 2x6's in most cases... Steve

[rod gervais]

2x4's are still used to carry 2 floors and a roof...... and will carry that all day long without a problem......

Of course they are installed at 16" centers to do that - whereas 2x6 are installed at 24" centers.......

so from the perspective of compression load....... the 2x6's will carry a wee bit more - (that because the area of 2x6's @24" centers in a 4' bay is 24.75" square vrs 21" square for 2x4's @ 16" centers.) but in the case of a home studio it doesn't make a bit of difference - this because you could never put enough load on anything to even begin to compress anywhere near the unity of the member.

As far as stiffness goes - there are those who believe that stiffer walls are better at lower frequencies....... in fact - it seems that Steve and I once had a telephone conversation relating to that.

Now I will admit that I am not a physicist - and do not understand all of the math involved.......... but I do know that sometimes what works on the plan table just doesn't work in real life.......

Each wall assembly has to be taken on it's own merit - and (regardless of what the "models" say) only actual measurements in a lab afterwards will tell the real story.

Here are 2 wall assemblies........ both 2x4's - exactly the same except for 16" centers vrs 24" centers........ guess what wins for LF..... slightly - ever so slightly.........

The following information is from the Canadian Study........ IRC-IR-761......

The examples are fully double wall systems.......... 2 layers of 13mm drywall - 2x4 studs - 90 mm glass fiber insulation in the cavity - 25mm gap filled with air - 2x4 studs - 90mm glass fiber insulation in cavity - 2 layers of 13mm drywall.

The readings on the left side of the chart are with 16" spacing - thus the right are 24" spacing.
16" Spacing----------------------------- 24" Spacing
TL-93-275----- Frequency------------- TL-93-286
21.7-----------------50 hz-------------------21.6
24.3-----------------63 hz ------------------26.3
29.3-----------------80 hz-------------------31.1
35.6----------------100 hz-------------------35.0
40.3----------------125 hz ------------------40.9
46.2----------------160 hz------------------ 47.0
51.6----------------200 hz ------------------52.3
58.0----------------250 hz ------------------57.4
62.7----------------315 hz ------------------60.5
67.6----------------400 hz-------------------65.0
70.4----------------500 hz-------------------67.0
73.6----------------630 hz ------------------70.7
77.2----------------800 hz ------------------73.1
79.4---------------1000 hz-------------------77.5
82.7---------------1250 hz ------------------82.8
86.5---------------1600 hz-------------------86.9
88.1---------------2000 hz ------------------88.1
82.4---------------2500 hz-------------------83.7
79.6---------------3150 hz-------------------79.0
84.3---------------4000 hz-------------------82.9
89.2 --------------5000 hz-------------------88.4
90.3 --------------6300 hz ------------------89.7

As you can see - pretty much everything below 250hz you gain by the 24" centers over 16". AND - where you don't the differences are so small as to almost be non existant. Note - this is not so much of a difference that I would consider it a large gain - but it is a gain none the less.

Things are not always as they seem.............. so I go back to something that I have been saying for years........... and that is this:

"If it isn't tested and rated - no matter the math - no matter the logic - you build it at your own risk .............. you might get lucky and find a goldmine - or you might throw your money away..............."

Sincerely,

Rod

[cadesignr]

I have a question Rod. It would SEEM, walls are simply a panel absorber in disguise, correct?
If this is the case, would one gain the same proportionately increase in absorption, if one were to build a membrane absorber, IN FRONT OF a wall, EXACTLY like a wall, only using a 4'x8' or 10' panel of gyp bd, on a 4'x8' or 10' frame that is fastened to the FACE of a wall and SEALED, whereby the wall surface becomes the BACK of a membrane absorber, and a full sheet of gyp. bd, is the front membrane of the absorber?

Also Rod, I've asked about this before, and STILL do not quite understand about absorption coefficients of membrane absorbers.
Let me put it this way.

IF a person determined he needed absorption at a certain low center frequency, the absorption FREQUENCY of a membrane absorber can be determined by a formula, which is a ratio of Mass/depth. But just as resistance absorbers have a coefficient of X Sabines per square foot, so must membrane absorbers. And if one were so inclined as to calculate the AMOUNT of absorption required at the determined low frequency, how would a person determine in Sabines, the absorption gained from a certain size membrane absorber? From my understanding, only testing will qualify this sort of data, and if so, how do people know they are indeed getting the required absorption with homemade membrane absorbers. This is what I don't understand.
I know the mass and depth affects the frequency, but no one seems to be able to tell me how to SIZE fits into the puzzle, as the usual answer is.......you have to have them tested Which tells me there is NO formula for determining how many, or size, or anything, in regards to what is required to precisely meet the total absorption goal. Hmmmm, does that make sense? Sorry, this one belongs in the Acoustics forum, but I've already done it. And I STILL don't understand why people arbitrarily build these things at a certain size, without even knowing how MUCH absorption they are indeed getting. Same with Slat absorbers. Ambiguity is NOT my friend.
fitZ

[z60611]

cadesignr

This is one of those posts where I give ideas, not advice.

I've never built a studio wall, but I've read that:
a) with walls, if you build runing the first layer of gypsum vertically, vs running the first layer of gypsum horizontally, you get a different resonance frequency
b) If you change the size of the gypsum from 8' to 10', you get a different resonance frequency.
c) if you put electrical outlets in the walls, you get a different resonance frequency.
d) if you hang things on the walls, you get a different resonance frequency.

In short, you can't predict until after you've built the walls, what the resonance is going to be, and if it's going to support or detract from the room -- for example if it resonates at a strong room mode that could be very hard to fix. Walls are big things. Whatever they do, they do a lot of. One solution, for example, would be to tear down the walls and start over.

IMUO (in my unexperienced opinion) flexible walls are not something that I'm willing to experiment with. RSIC or rigid massive interior walls are good things for my room. (townhouse basement HT)

So, yes walls are a panel absorber. But that's not nessessarily a good thing, because it's really hard to predict what frequency it will be a panel absorber at. You can still build your walls with the intent for them to be panel absorbers, but it depends on the room, and what's around it, and the budget, what you want the wall to do acoustically when it contributes to the room.

Every wall probably gives some bass absorbtion (either by actually absorbing it, or letting the energy out of the important room and into the next room), and little high frequency absorbtion (because most of it is reflected back into the room). For example, a wall might have the following absorbtion coefficients: 0.10, 0.08, 0.05, 0.03, 0.03, 0.03
Now that doesn't look like a lot, but you have a lot of wall, so when you multiply it by the area you get a lot more sabins at 125hz than you do at 4khz. It is somewhat fortunate that this curve is opposite to fiberglass/rockwool.

know the mass and depth affects the frequency, but no one seems to be able to tell me how to SIZE fits into the puzzle, as the usual answer is.......you have to have them tested

I believe that you have to have them tested to figure out what the frequency and absorbtion characteristics of what you've just built is. You may be able to do the tests yourself. I believe that a panel absorber will have the same absorbtion characteristics all over its surface -- to get the sabins (sound removed from the room) you multiply the absorbtion coefficients by its surface area. If you have one 2'x2' surface area panel, and then stick 15 more just like it right next to it, you've increased the sabins for each of those same frequencies by 16 times.

You might want to have a glance at http://www.bobgolds.com/AbsorptionCoefficients.htm . About 95% of the way down there's a section called Helmholtz Absorber Examples. It lists a bunch of designs that Everest had success with, followed by a comment about how hard it is to DIY these things from the prediction formulas. Companies that make these for a living say they make/test/redesign/make/test/SwapMaterials/make/test/ over and over.