slab or floating floor?

there is a crack in the slab and part of the floor in the drum room is slightly at an angle (not too bad, maybe 2"). should i use shims for the drum riser or should i just fill in the cracks and level the thing w. concrete? leveling seems like the obvious choice here... call me crazy but part of me thinks that the slanted concrete floor might help with acoustics? 1. because there is a crack in the slab it is already slightly decoupled? 2. slanted floor, flat ceiling = nonparallel surfaces?

Nearly 3 am here, so this will be kinda short - for the "drumhead" walls - what about having cellulose insulation blown in, then patch the holes and add a couple layers of wallboard? Not perfect, but not bad. It would be quite a bit better if you could pull off the inside panels and at least use Resilient Channel and two new layers of wallboard, with SAFB's for insulation. Sometimes pix don't really show things as clearly as a drawing - is your roof framed like this, or am I not seeing the pix quite right?

Jeff, just talked to John and it looks like your paypal notification got eaten by a spam filter - can you resubmit? thanks... Steve

sorry for the delay! i was out in Cally for the weekend. :lol: the picture of the roof... you pretty much got it! I'm looking at your drawing from this perspective: the left wall is the north wall (back of the control room) the right wall is the south wall (garage door) the top beam of the roof doesn't hang down. the slanted roof joists are flush with the top beam. there are 8 joists, and if we number them 1-8 from east to west... on joists 3, 5, and 7 there are 1"x6" boards going across the top for support, like an "A" frame. the tops of the 1x6s touch the top beam, forming a tight trianglular shape. about the donation, i'll resubmit somehow, but paypal deducted the amount from my card already... this is why i hate paypal! :evil: many thanks!

Man, that seems like a wimpy roof frame - how come it hasn't fallen down yet? :cry: Do you have a plan to make it work for you, or do you need me to help you design something that will be workable for isolation without getting buried in the rubble? The way it is now, I'd be scared s***less to hang ANYTHING more on those rafters... Steve

hmm. the roof is only 2 years old. maybe hanging something is not a good idea...? there are headers that go across the top. should i add more headers and make a ceiling across them instead of going with hangars from the roof? thanks!

how about something like this?

Headers that go across the top of what? Would they be from right to left across the tops of the walls in the drawing, or something else? Some term definitions, to help when pix aren't used - Header - a heavy beam across the top of a wall opening, helps strengthen the wall so the opening (window, door) doesn't collapse with the weight of the roof Rafter - lumber set on edge, usually pitched, on top of which roofing material for the outer roof is fastened. Joist - a horizontal framing member, used for floor framing or ceiling framing. Cap - top flat-laid board of a stud frame. Plate - top or bottom horizontal, flat-laid board of a stud frame. Stud - vertical board of a stud frame, usually 2x4 or 2x6. Tie - a horizontal board used to maintain spacing between two other framing members. Collar tie - a horizontal framing member used between opposing rafters to keep the walls from trying to spread due to downward force of the peak of the roof. Cripple - a short stud, used under (or over, I think) the horizontal framing of a window. Jack - an angled rafter, used mainly on hip roof construction to tie the end pitched roof section to the two side pitched roof sections. Truss - a (usually) pre-manufactured roof framing member, consisting (usually) of two rafters, a full-width collar tie, and several diagonal braces (called Chords) - all held together by stamped steel plates at each junction (sometimes plywood gussets are used instead, when site-built) - trusses are engineered at time of design for the specific loading needed, and cannot be calculated with normal span tables - the engineer takes in to consideration the grade of lumber and several other factors of the truss design to arrive at top and bottom loading, etc. Birds mouth - the small notch made in rafters (non-truss designs) so the rafter can sit flat on the caps of the stud framed walls. Probably forgot a few dozen terms, but these are the ones I see mis-used most often. Anyway, if you could clarify what you meant by "header" - preferably by another markup of the drawing, if possible... Steve

:oops: thanks for your patience with the dumb noob. there are 8 rafters in the roof. right now there are 3 "joists" that go east-west. i hope this will help clarify the situation.

OK, kinda thought that was what I was seeing in the pix - now, as soon as I get some time to figure out WTF the builder had in mind with those joists, and why they didn't tie the LOAD bearing walls together... Right now, it appears that your ridge beam is bearing on the end wall frames, and it's the only thing keeping your rafters from collapsing. This is typical of older construction, and the reason we see so many "sway-backed" houses in older parts of town. Gimme a while to get some ideas together, and maybe we can re-design your space so it can get sound-proofed... Steve

"now, as soon as I get some time to figure out WTF the builder had in mind with those joists, and why they didn't tie the LOAD bearing walls together..." - OK, one brain fart bites the dust - those "joists" are a sort of "collar tie", in that their purpose is to keep your end gable wall from "folding in the middle", therefore not being able to support the ridge board, which in turn supports the upper ends of the rafters. Possible your best bet might be to do as you drew, not relying on the upper house structure at all but doing free-standing inner rooms - I'll get back on this as time permits. Meantime, did you already post the exact dimensions of your rafters, including spacing? If so, nevermind - if not, mind :wink: (as in, I need this) Steve

steve, i'm thinking i shouldn't mess with the rafters or roof given what you said. but i also want the ceilings as high as possible and within modest budget. do you think the joists can support my inner room ceilings without causing a problem with my end gable wall? do you think i'll need more soundproofing other than the ceilings on the inner rooms? the only room i'm REALLY concerned about is the drum room. also, how do you propose measuring the rafters? my ladder doesn't reach as high as the roof peak. and any attempt to reach it would be life threatening. any ideas? :roll: thanks again!

I've built trusses in place using plywood gussets glued and nailed in place, that have held up in near hurricane winds - it's not that hard once you have the concept. It looks to me like those joists are too far apart and too small to support much of anything. Building trusses in place will be a LOT stronger, and can probably buy you some more headroom as well. Soundproofing - even a mediocre 2-leaf barrier will beat a pretty heavy single leaf barrier, even one with several layers of gypsum - that's why this needs to be addressed for sound isolated rooms - here's a drawing that illustrates the basic concept of mass-air-mass soundproofing - http://www.johnlsayers.com/phpBB2/viewtopic.php?p=15478 Measuring the rafters - not necessary to get to the peak of the roof - all I need is the total width of the space, left to right in the drawing I posted - then, thickness and width of the rafters and their spacing (how far apart) - all this can be measured at the top of the wall where the bottoms of the rafters sit... Steve

steve, i'll do my best to make this as clear as possible: there are 8 rafters on each side of the roof, and numbered from east to west 1-8. i measured from centers and came up with the following: NORTH side: EAST WALL to rafter 1: 16" 1-2: 16" 2-3: 16" 3-4: 16" 4-5: 16" 5-6: 16" 6-7: 16" 7-8: 16" 8- WEST WALL: 15" SOUTH SIDE: EAST WALL TO RAFTER 1: 14" 1-2: 16" 2-3: 16" 3-4: 16" 4-5: 16" 5-6: 16" 6-7: 16" 7-8: 16" 8- WEST WALL: 15" looks like the EAST garage wall is slanted 2"? where do we go from here? :lol:

OK, 16" centers is better than 24" - now, we need the actual dimensions of the rafter lumber - looks like they might be 2x8's, which depending on the age of the building could be anywhere from a REAL 2" x 8" down to modern day 1-1/2" x 7-1/4" - Next I need the distance from one wall frame to the other, in the direction the rafters run (so the peak of the roof would be in the center of that measurement) - What I'm thinking of in order to get strong support for ceiling panels is something like this; only that's a barn, and has trusses only on 12 foot centers fastened to poles in the ground, then the rest of the roof is supported by the 2x6 purlins across the tops of the trusses. I built these trusses in place several years ago so I could remove the poles in the center of the floor - we get 80-90 mph winds regularly in winter, and it's still there - 'nuff said...

ahh, i see. the rafter lumber measures out to be 1.5" x 5.25" - can this be right? :shock: the span of the edge of NORTH wall sill to edge of SOUTH wall sill is 25'1" - 25'1.5" forgive me if i'm getting this wrong, but using the design in the photo where the top roof beam runs perpendicular to the trusses would mean that i'd have this running NORTH-SOUTH spanning both rooms. is there an alternative version where the support truss runs EAST-WEST, parallel to the top roof beam? thanks!

It's possible, although it would need to be done differently - what's your concern with running perpendicular to the peak, is it room to room isolation? Steve

yeah, i guess, plus the span is 25' as opposed to 12' east-west. i'm open to your suggestions though!

I'm a newbie myself, so I don't have much to add, although I am following this thread to benefit myself. There is one thing I would like to add though... At the beginning of this thread, you are taking science and numbers into consideration to try to reduce the sound that bleeds off to your neighbors. This makes sense, but remember that your neighbors are humans. What I mean by this, is that what they find acceptable can vary from person to person. I have learned this the hard way with a problemsome neighbor (who has since moved, thank goodness). I don't know what the SPL of my roads are (they are pretty close), but I'll ASSUME your 55 number for an example. The neighbors ALL accept this, probably because there isn't jack they can do about it. But even if I get the bleed from my building down to 20, 15 or less, I had one neighbor that WILL call the police in the evening hours. Even if the sound is so quiet that it wouldn't disturb the squirrel in the tree, if he can actually make out that there is a rhythym (proof enough that it came from my kit or system), he'd call. All this, and when the trucks go by, it rattles his windows! All I'm saying is that it takes one of these jerks, and all the science goes out the window! He used to call anytime of the day, and our police department responds to all calls, even if repetitive. I tried to reason with him, asking if I could have certain hours, or anything else I can do. His response-- "No, I don't want you playing drums at all." It just depends on the neighbors.

That's what cyanide was invented for... :evil: Seriously though, good comments - this is why I mention from time to time that communication (and a mild amount of ass-kissing) goes a long way toward peaceful coexistence - if you start out making noise, and try to stick to the "rules" of acceptable levels, someone like this neighbor will ALWAYS bitch, even if you're BETTER than the so-called rules require in your area. If you start by having a talk with the neighbor(s), and explain that you do NOT want to cause them any problems, and follow it up with some "dime store science" display, like having someone play full frequency music inside your area as loud as you'd ever do, standing WITH the neighbor in THEIR space with a sound level meter and, while communicating with your helper, have them turn DOWN the music til the neighbor is happy, then measure inside the room and note the DIFFERENCE between the two levels, that will give you a good idea of how much MORE sound isolation you need. This also gives the neighbor less reason to bitch, because you're obviously trying to be the good guy - it's a lot like the ploy of inviting the neighbors to your party so they'll be less likely to call the cops, even if they DON'T attend... Not much time right now, but Jeff, don't worry about spans - trusses are used every day that clear-span 120 feet - it's all in the design and implementation. As to isolation, that's what resilient hangers are for... Steve

lol! :D that sucks for you Joey, thanks for the heads up! in college, i had a neighbor just like that who would actually pound on the wall until we stopped playing. I've spoken with the neighbors, and they're cool. the one guy plays keys in the church down the street... his son is a rapper though! I'm starting to get the feeling that we wouldn't really need forums like this if you drummers weren't so damn loud :shock: butcha know i love ya when ya crush those things :P

steve, i just discovered that there actually is insulation in the east wall, separating the house and the garage. do you think i still need to take down all the drywall or can i just put up another layer of drywall to help w. mass? thanks! p.s. the guy installing the door is coming tomorrow so the sooner you can get back to me the better!!! THANKS AGAIN :wink:

One more layer of properly caulked and sealed 5/8 drywall will give you about 6 dB better isolation all across the spectrum - a THIRD layer would improve that by another 3 dB - the RC wouldn't do much of anything for the bottom end, but will improve the upper midrange isolation by over 10 dB in some cases - worth it especially if playing live drums - those cymbal crashes need all the high mid iso they can get. If your walls were insulated half-assed, they might still ring - I wouldn't chance it, but my luck is so crappy I don't try to get away with ANYTHING I can't prove out in advance... Steve

all right... change of game plan. i think for the better, though. 8) i'm now planning on building new walls on top of the new floating floor instead of trying to mess around. i took down the drywall and yes there is crappy wall insulation there. i'll leave it, but the plan is now to build the floor for each room, put the individual walls for each room on top of said floor, then put the ceiling on top of the walls. floor first: here's the idea in order, please provide thoughts. 2x6 joists up on side, sitting on neoprene pucks 3 pcf insulation/rockwool tyvek 3/4 osb roof roll 3/4 osb laminate flooring/area rugs the major area not mentioned above is cabling and cable troughs for power and audio. i plan for the noisy computers and d/a converter to be built into the west wall slat resonator, which means i'll have to connect audio (xlr & 1/4") send & return, midi, usb, ethernet, firewire, phone, computer monitor cable through the floor. 1 trough for all non-audio wires 1 trough for audio snake send 1 trough for audio return am i missing something? how is it going to be possible to add wires through the trough? thanks! :wink:

Using those materials for a floated floor would give a resonance of around 31 hZ, which means that you'd have no isolation below at least an octave and a half ABOVE resonance, or around 45-50 hZ - best you could do in that case is to make SURE you have enough rockwool in the cavities to be compressed by about 1/2" when the floor goes on the joists - that would help damp the floor and keep ringing down. Better, if you can, would be to put ONE of those layers of OSB down and then plastic, and pour a 3" thick concrete slab on top - this would lower the mass-air-mass resonance to around 15 hZ, which would drop even further when you added the weight of the walls and ceiling, to around 10 hZ - this would put all audible frequencies above your resonance, ensuring good isolation throughout the audio range. If that's not practical, adding a layer of 5/8 gypsum between the two layers of OSB would help lower the resonance; you want this as low as you can get it, but definitely sub-audible range. In either case you want the insulation to compress about 1/2 inch, maybe 3/4" - more would start to short out the floor, and much less would not damp the floor enough. Troughs, in order to add wires, need to have removable lids - if you don't want to design lids that have enough mass and can seal when you close them, then using PVC conduit makes more sense... Steve