Hi Knightfly
Thanks for the post - you have to be one of those guys who can survive on 2 hours of sleep, based on the number of questions you answer on this site!!
Soooo, that explains the "eyes" -- Got it! ;-):mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen:
Now then... scalpshifter sent me a private message, to which I responded, and I have his blessing to post it here...
scalpshifter wrote:
Thanks for your input regarding my wall to ceiling delimma.
No problem. :cool:
I liked the idea you suggested of tucking parallel joists inbetween (and not touching) existing joists.
Yeah, that should be a winner, if you can achieve the clearance you'll need to put your panels on top of your existing joists.
In fact, you may want to use OSB as your topmost layer inside your attic -- that way you should be able to walk or crawl on it afterwards... Or store lightweight stuff on it.
My question is where can I find information about whether or not 2x6 or 2x8 lumber is adequate for the largest span (ranges from about 14 to about 18 feet when all is said and done)? I plan on adding 2 layers of 5/8 drywall to the ceiling system.
See this thread for information about span tables.
Fortunately, the Internet being the way cool thing that it is, there are some on-line calculators, like this one that I just found, that make it much easier for novices like us to use.
I'm not sure what kind of lumber is available in your part of the country. Out here in the West, it's usually Douglas Fir, #2 or better.
Steve is good with span tables. I know he's behind right now, but if you do your best to come up with all your specs and then post them for feedback, he (and others) should be able to post back their "thumbs ups" or "thumbs downs."
You will need to have these calculations in order to secure your building permit.
Best of luck! I'll be interested in seeing your progress. ("Progress" doesn't require construction -- this stuff is 90% planning, and 10% doing!)
--Keith
That was the right link; may 30, 9:13 pacific; should be 11 pm your time, daylight time notwithstanding. there are several drawings, it's the very last one on that post.
Keith, now you know; I photoshopped out the 47 mil-spec toothpicks per eye before posting that :shock: plus, one advantage of being (among other more useless things) a licenced electrician - inserting yer pee-pee into an electrical socket only wakes you up a bit instead of killing you - can be very helpful when coffee quits working... :roll:
Spans - with no other support, 2x8 doug fir # 2/btr will (@ 10 psf dead load) span 13'6" on 24" centers, 16'6" on 16" centers, and 19'1" on 12" centers.
BTW, that 10 pounds per square foot INCLUDES the weight of the framing, so you can't put 10 pounds of DRYWALL per square foot.
A small clarification of terms in the interest of clarity... Steve
Thanks for the terminology lesson - I'll commit it to memory (if there is any left...) :lol:
Looks like I am going 2x8 w/12 inch centers!!
Now to psych up to overcome both economic and activation energy barriers!!
Thanks again!!!!!!
E
Somehow the term "enlightenment" does not seem to fit whatever stage I am in. But perpetual confusion has worked for me for 49 years...
I do feel an affinity for stage 22:
22. OK, I'm starting now, but everyone watch every step and stop me if I do something stupid!
I am not sweating the drums because the space I have is too small to cram 3 or more people into - but I WILL miss the jams and rehearsals!!!
In the last few years the bulk of my efforts have been more in keeping with the digital paradigm shift of "assemble music as you go", at least as far as clients are concerned. And for solo stuff - the CR is good for me!
Of course, after saying all that the first thing I will want to do is record drums...hence the perpetual confusion...
BTW I have not even begun on the mini live room because:
1. I am short on dough (always), and
2. I have a lease running out in October and gotta put my gear somewhere!
So - it seems like my next task might be tearing down the sheathing on the inside of building exterior walls (?). I do not see how I can totally avoid a 3 or 4 leaf problem unless..
I put only a single frame wall on the floated floor, cover one side with lots of mass and cover the other side with fabric, and do the same (fabric, air, mass) on the adjacent exterior wall.
Somehow that scenario does not sit well, yet... :?
BTW, that 10 pounds per square foot INCLUDES the weight of the framing, so you can't put 10 pounds of DRYWALL per square foot.
i've been wondering that. so, for example you'd deduct 2.5 lbs per square foot for 2x8s on 12" centers (assuming 20lbs per 2x8x96)
so you could then add 7.5 psf of drywall safely ... sound right?
thanks!
dan
I have been thinking about the leaf “law” and trying to understand the physics involved. In the diagram below I have drawn the MAM condition In Panel A and then two variations. Panel B is the MAMAM (3 leaf) condition. Panel C is the same as B except that the third leaf is not parallel to the other two leaves.
Is it true that the detector in Panel B will hear a higher amplitude signal at specific frequencies than in Panel A? That seems counterintuitive, even allowing for resonance, because there must be additional energy loss passing through the third leaf.
If so, will that signal only occur at sympathetic resonant frequencies of the 2 leave preceding the third leaf?
Maybe what I am confused about is that the shape of the measured TL curve may show an embellished dip at resonant frequencies in > 2 leaf systems, but the global STC rating should improve with additional sound barriers even if they are additional leaves - right? Or maybe not if the TL curve becomes so crappy at a particular frequency that it pulls the STC rating down (since STC is defined by a specific dB variation from a standard STC contour).
Finally, if the panels in the systems are modeled as uniformly resonating planes (which the are not because I am sure they have all sorts of resonant modes and configurations) then in the system in Panel C the planar compression (sound) wave will create a pressure gradient across the face of the third leaf, which should disallow sympathetic resonance to some degree, thereby reducing the degree of resonance based sound transmission. This is akin to being off axis with a microphone to reduce sound pressure and alter the tonality.
Or is my head totally in the sphincter zone…? :shock:
. . . if I build a double framed wall (inner and outer leaf structure) things will be wacky (scientific term) when that structure approaches the existing shell which already has sheathing on the inside and paneling on the outside. . .
Why are you "building a double framed wall"? Why aren't you building a single leaf single framed wall for your inside leaf and (before that, obiously) ripping off the "mass" on your existing original construction outer leaf wall, and beefing up the outside leaf from the inside (between the studs)?
You seem to be approaching this situation as though you cannot avoid a triple leaf. Perhaps you can't avoid it, but I'm not convinced yet.
Scalpshifter:
You have put so much in your post I can not clearly address the points. The closer masess are, the more tightly they couple. With athree or mroe leaf partition, you hve masses closer together.
Andre
Thanks for the thread Sharward - which I had not come across yet - I'll get to readin' it shortly.
OK - I just read it and that was very interesting - my interprettion is that is the air between leaves has an "exit", meaning and inencumbered escape route, then its performance as a spring (to carry the compression wave from leaf to leaf) is compromised and the multileaf problem is reduced...
Back the current commentary...
You are correct that I can remove the interior mass on the exterior wall and stuff it in the wall - I just have to:
1. Overcome my dominant double dose of the "lazy bastard" gene, and
2. Decide if the gains I can expect are necessary for the work I plan to do.
3. Do it so the triangular space is not totally ugly between the two walls because that will be a walkway - though it really does not have to be - I could use it for storage or machines I 'spose...and save myself the hassles of putting in a new outside door (but I gotta get my console in there somehow.... maybe in the giant window hole before I install the glass...)
Also, Hi Andre, thanks for your comment on the probability of matching masses increasing with increasing number or leaves - that makes perfect sense!
Please don't anybody waste their precious time with my issues unless you really want to - I know we all have lives (more or less) and I will do some F.A. Everest reading in the next 2 days to see if I can figure some of this stuff out without hassling other brains!
But if you just have to...I am all ears (I guess that is eyes in this case) and will be eternally grateful! :D
THANKS!!!
. . . I can remove the interior mass on the exterior wall and stuff it in the wall - I just have to:
1. Overcome my dominant double dose of the "lazy bastard" gene . . .
Gee, can't help you there. :roll:;-)
. . . and
2. Decide if the gains I can expect are necessary for the work I plan to do.
Well, triple leaf is much more detrimental at the low end, so if you plan to do a lot with bassy stuff (and I would think that you would), then it's probably worth the effort. But, only you can decide. :)
3. Do it so the triangular space is not totally ugly between the two walls because that will be a walkway. . .
There are lots of ways to make a "partition" that breathes... Insulation with fabric over it would work -- John specs "inside out" walls in a lot of his studios, where fabric covers walls instead of gypsum wallboard (the wallboard is on the outer side of the room). You could do that pretty easily and it wouldn't look like an unfinished garage. :cool:
Also, Hi Andre, thanks for your comment on the probability of matching masses increasing with increasing number or leaves - that makes perfect sense!
Your welcome. There is no "probabality" about it. It is what happens. Paul Woodlock has an excelltn example with a free stranding door just moving betwen a wall!
Good luck with your studio!
Andre
i don't know that much about all this, but a couple of points ... sorry, it looks like you're going to be the victim of my morning "need to post to the forum" jones. :P
i think the intertia of the air is a factor, if there is a lot of air in a contricted space it doesn't matter if the edges are open to the outside world, there is still going to be a resonance effect.
it's kind of like having a crowd of people leave a building, it takes time, and if you tell them to turn around and come back in and then to leave again, 100 times a second or so, it doesn't matter how big the exit is does it?
i'm submitting that for the lame analogy of the year award
also take the example of a guitar or violin. guess what they have holes in them, and they still resonate, in fact the hole is what alows the sound to escape and be heard louder. right? so a leaf system with holes in it, or an "escape route" is still going to have a resonance
at resonance freqeucny and below, the air in the cavity essentially acts as a SOLID, essentially hard-coupling leaves together. at resonance, the system performs WORSE than the two leaves would if they were just pressed together.
so you can see if you had the right combination of leaves and frequencies, you could end up with a pretty low performing result.
can it amplify? maaaaaaayyybe. no one's proved that to me yet. but that doesn't matter really, what matters is these factors have to be taken into consideration when building walls, if you want to do have good results.
i just thought i'd throw that out there, i'm pretty sure this is correct.
i'm not sure how exactly to explain the whole triple leaf thing though. i think it comes down to, avoid if at all possible, but if not, do what you have to do.
let me know how that everest reading goes
dan :D
Just in case that "E" in some of your signatures stands for "ephemeral", and just in case I goofed on the previous link (since I've yet to see any indication you've found it :=) here are a few "germain-ities" -
Specifically, read the side-bar I added along with the screen shots.
If you can get your outer leaf (like the siding and outer frame) beefed up by adding inserts (or complete extra layers outside, whichever works WITHOUT adding more than about a MILLIMETER of air space between layers, the next (and ONLY) thing is a second, ISOLATED, inner leaf with its attending support system. Where ceiling meets wall (outer or inner) if there are areas where framing is the only mass, consider that (hermetically sealed) wood framing is worth approx. equivalent of 2/3 that thickness of gypsum.
Where headroom is limited, it gets trickier to maintain separation of inner/outer leaves; where not, just build an inner frame wall, rest the inner frame ceiling joists ONLY ON THIS INNER WALL FRAME, and sheet rock it.
If you have LOTS of space, and need LOTS of isolation, you can up the size of ceiling/wall framing and put your gypsum on the OUTSIDE of the inner frame; for the ceiling especially, this will help keep the stuff in the air where it belongs, plus leave you with stud cavities you can fill with insulation and cloth-cover, or slat-cover, killing at least part of the "acoustic alligator" at the same time.
Gotta run for now... Steve
Oh, the interesting "3-leaf" experiment -
http://forum.studiotips.com/viewtopic.php?t=1198
Thanks to all you guys for your input - and that expeimental data in the link kinghtfly posted was darn interesting (though I will, of course, have to repeat it.. :D since I am a science nerd)... Plus is finally clicked that small motions at one end of a MAM system can result in large motions at the other end as a function of the masses and the spring constant (if it obeys Hook's law...).
I also totally understand and agree that air has viscosity and experiences inertia and therefore even "free" air (air that can escape out of a cavity) will still have some spring quality. I suspect that as the as the freedom approaches infinity the spring response approaches zero - but never gets there completely.
I think the violin example is related and I need to digest that concept some more fo' sho'...
Knightfly, I apologize for not letting you know that I did find and read the material, including your sidebar comments, in the May 30th link - my bad! It was great and I'd like to get my hands on the program that does those calculations 8)
I am going to remove one sheet of that sheathing and see what is under there and decide what to do to fill in the gaps to increase mass.
I think that Sharward is 100% correct that I can figure out how to do the whole project with single frame walls and no multileaf (>2) problems - I'll sketch it out and post it for critique shortly. I have a couple questions...
1. How many sheets of 5/8" drywall can one hang on one side of a single frame 2x4 wall before the leverage (of the gypsum mass extending away from the wall) causes significant wall distortion/buckling or other stability concerns?
2. Is RC necessary with single frame walls if the entire room is floated and isolated?
3. How does RC compare to the ISOmax hangers in price, performance and ease of installation? I'll be careful, but I'd hate to spend time and cash using RC and have one errant screw hit the framing and screw the entire pooch flanking-wise.
BTW Everest shows some interesting alternatives including a 3 leaf system consisting of: drywall - framing (airspace 1) - drywall - RC (airspace 2) - drywall..... with an STC of 56 compared to an alternating stud system (STC 56) and a double framed system with the same amount of drywall (STC of 63) (Fig. 13-16, page 186).
sketch coming shortly...
Here is a sketch of my rooms with the brown representing framing and the green representing the positions of drywall or sheathing mass. As far as the two trapezoidal rooms are concerned I see only interfaces with two leaves (and a few weird angle juxtapositions). The area to the left is not a big concern since it is office/chill space only... :lol:
I am pumped!
1. How many sheets of 5/8" drywall can one hang on one side of a single frame 2x4 wall before the leverage (of the gypsum mass extending away from the wall) causes significant wall distortion/buckling or other stability concerns?
At least three; but if you're looking for high isolation, stiffness doesn't hurt either; I'd go up to 2x6 just on general principles.
2. Is RC necessary with single frame walls if the entire room is floated and isolated?
How do you "float and isolated" with a single frame? If you mean, do I need RC when building a room-in-room when the inner leaf consists of multiple layers of gypsum all placed on one side of the inner frame, the answer is no. This construction is almost entirely governed by m-a-m phsyics, where the two masses and the air gap determine the overall resonance, at which frequency the isolation will be worst. (not zero necessarily, you do still have mass there; but definitely worst.)
If your m-a-m resonance is at (say) 14 hZ, then it will be at least 1-1/2 octaves ABOVE that before the deleterious effects of that resonance won't cause a noticeable weakness in the isolation curve. So a low B on a 6-string bass (around 31 hZ) should be attenuated fairly well with that low a resonance.
3. How does RC compare to the ISOmax hangers in price, performance and ease of installation? I'll be careful, but I'd hate to spend time and cash using RC and have one errant screw hit the framing and screw the entire pooch flanking-wise.
Haven't priced EITHER lately, not since steel rose in price by 300% - if you're planning on a full room-in-room, there may well be no need for either. The Isomax stuff is easier, maybe a dB or two better, and 'way more expensive (unless you buy your RC from an acoustic dealer on the web) - some web dealers want as much PER FOOT for the stuff as I've paid for a 12' stick :shock:BTW Everest shows some interesting alternatives including a 3 leaf system consisting of: drywall - framing (airspace 1) - drywall - RC (airspace 2) - drywall..... with an STC of 56 compared to an alternating stud system (STC 56) and a double framed system with the same amount of drywall (STC of 63) (Fig. 13-16, page 186).
Rule # 13b - don't do ANYTHING the same way the British do it, unless you're MADE of money - some points to consider: The british seem to like 6-leaf walls, (which they refer to as "triple camdens") with each wall getting heavier and more expensive, and taking up more space - sure you can eventually get as good isolation that way, and no SINGLE leaf's failure will be catastrophic - but there are cheaper ways that take up less space and get the same results.
Keep in mind that all Everest's numbers are STC, and that this doesn't even consider ANY frequency below 125 hZ. The man, great as his contributions, was nearly 90 when the SUB woofer was foisted upon us... - so any wall with phenomenal mid-range performance will look SUPER when using STC, but the wall may very well not even slow down a kick drum's primary thud. This is what happens with multi-leaf walls. Bottom sucks; mids ROCK. not exactly what modern music needs for isolation, not to mention tractors/trucks/jet planes, and other "rumblers" (trains for example)
I'd like to get my hands on the program that does those calculations
Sorry, it's an OLD demo - the newer demo is randomized so pretty useless, and the full program costs $1000 from Marshall-Day acoustics in NZ - I'm pushing it just doing what I do with it, I'm almost feeling guilty enough to plop down the $1k for the real deal, but probably not THIS week... Steve
rule # 13b - don't do ANYTHING the same way the British do it
Does that also mean I should cut out the tea and scones after sex? :lol:
Thanks for the info - I will do as much 2x6 framing as possible and probalby avoid the RC issue altogether.
We are having a great (but highly electrical) thunderstorm so I am getting off the CPU!
Thanks a million for the help!!!!!!
Does that also mean I should cut out the tea and scones after sex?
If you like your sex steamy and gritty, then the tea and scones should happen first... :?
Hi To Anyone Interested in This Project
I have made a little progress - installing OSB above existing rafters then starting some initial framing. Here are some pix
I think I now have a decent handle on the multileaf issues and whatnot. I'll post some more pix as I go - especially when I am pretty sure I am totally confused :?
I have removed earlier links to pix to keep my server from getting too cluttered :wink:
scalpshifter,
wow, nice pix!!
putting up that OSB on the ceiling trusses must have been a huge pain. looks very neat and well done though.
too bad you had to delete older links ... these are good pix to save for future readers. don't forget you can post some pix directly to the forum ... see "add an attachment" below the message entry box. plus it's more convenient for readers too.
keep it coming!
dan
Yup, that stuff is heavy and it was pretty comical trying to hoist it up there then get all the T&G fitted together - I learned alot about leverage!
I'm not done with that part yet but my first goal is to to get the CR finished so I stopped when I had that covered. In retrospect it might have been better to frame walls first because with the OSB up there I have a tough tme driving fasteners from the top down into the vertical studs - lots of toenailing...
The old links are consolidated into the new one so all of those photos are still there. I'll put up a few on the forum - thanks for the suggestion!
e
Here is the Status Quo
The PVC sections are to protect the AC wire I have kicked and squashed about 1000 times :cry:
You can see 2 of the 2 x 8 ceiling joists that are interdigitated with the existing rafters - there will be 17 when I am done (12" oc)
Bravo!!! Congratulations on what looks like a terrific job so far, and on behalf of everyone, thank you for taking and posting the wonderful pictures! I can see this thread becoming one of the favorites here. :D
Thanks Sharward
I hope this is useful for people to learn what NOT to do - like today when I had to removed ceiling joists and re-position them to get them exactly 12" OC. Those 20 footers are not cheap either and since my room has walls that are at a 12 degree angle relative to the existing rafters, every joist is a different length (i.e., once I cut them, if I move them the length is wrong = spend more money!).
Also, Iowa is hot this time of year and caulking that attic space with a heat index of 110 outside (who knows what it was in the attic) was a sweat-a-thon!
I am making some compromises with regard to the ideal 2-leaf scenario, but based on the amount of isolation I'll need for the type of work I do things should be adequate. Naturally, in keeping with my exquisitely bad timing and poor planning, I re-discovered on a CD we just completed that live drums can turn an average track into an awesome one, so I might have to do some extra work to create a "drum friendly" recording space!
But first - the control room must be complete by October when my current studio lease runs out!!