slab or floating floor?

sweet thanks but pouring concrete won't really be an option. would 2x4 floor joists or even 1x4 joists flat be better for the floor? i plan for a high & absorbent ceiling, would 2x6s on their side be overkill? made a few changes... how's this sound? 2x6 joists up on side, sitting on neoprene pucks 6.5" of insulation/rockwool (that's a lot of insulation and a lot of $$!) tyvek 3/4 osb roof roll <5/8 drywall (or would cement board be better?)> <roofroll?> 3/4 osb laminate flooring/area rugs thanks again!

The cement board is higher mass, so better - everything else will help lower resonance, except the concept of laying the joists flat. You want a larger air cavity for lower resonance. You might get away with 2x4's on edge with a concrete slab, but with the lighter floor the extra 2 inches will help lower resonance. I know all that insulation is expensive, but still cheaper than tearing it out... Steve

great steve, thanks. i think i'm going to go with the 2x6 floor in the drum room and a 2x4 floor in the control room, where it wont get nearly as loud. i'll have to weigh the options... what will give me the best results for my $$? a. to add more mass/layers on 2x4 studs b. to add more height/insulation on 2x6 studs i don't know if i can do the 2x6s in both rooms. gotta price it out & i'll get back to you!

I just "faked out" the Insul calculator (modified ceiling calculations) and ran two different scenarios - one, using 2x6's (defaults to standard house insulation, no choice) sitting on 6" concrete, resilient mounts, two layers 3/4" OSB - the other, using 2x4's, adding a layer of 5/8" gypsum between the two layers of OSB - M-A-M resonance is 2 hZ lower (35 hZ) using the 2x6's without the center gypsum layer. If you do BOTH the 2x6's and the 5/8" center gypsum layer, M-A-M drops to 30 hZ - I don't have weight specs on the cement board, I assumed it to be nearly twice the mass of gypsum and recalculated for 2x6, 2 3/4" OSB, and a center layer of 5/8" cement board - drops to around 27 hZ. With ANY of these, you will definitely want to overstuff the insulation a fair amount to damp the panels - this won't completely kill the boominess but I've yet to hear complaints from any of our members who've used enough insulation... Steve

do you know where i can get rockwool in nj? or, would any other insulation work here, such as r-30 fiberglass?

also, sorry i forgot to ask... will my floors need a 16" center or a 24" center? what's the diff? i imagine 24" centers would be best for low frequencies. Thanks! :lol:

Not sure on a rockwool source for jersey, I'm west coast - but for a floor you want either rockwool or rigid fiberglass at least 3 PCF, higher if you can get it. You want the batts to be somewhat compressed against the floor panels to damp ringing/booming. Floor joists - 16", even 12" if you can - more mass, stiffer construction, lower resonant frequency... Steve

Hey Steve what would the resonant frequency be on a floor with 2x4's, 2 layers of 3/4" OSB and rockwool?

Need more data - spacing of joists, whether walls and ceiling will bear on the floor, and if so what do they weigh along with everything in the studio - with all that, I can probably guess within an octave or so... Steve

About Rockwool in NJ: I spoke with a guy from Solatek [removed] x214 who was extremely helpful and knowledgeable about estimating my needs (including figures when compressed). However he said rockwool only came as loose particles, namely Kafco fiber, not huge slabs (i must be thinking of the seed starting/plant propogation medium). Anyway, he estimated i'll need 20 bags of 35lbs each and to call Nick Spagnoletti of State Insulation at [removed] because Solatek doesn't ship less than 600 bags at a time. I called, and got quoted $18.50 per bag, or $370 for insulation (not including delivery). 1. am i on the right track? i.e. is the loose stuff that i'll need? 2. is this price about right? Thanks! :lol:

I did a search on rockwool a while back and was amazed at all the plant propagation stuff, and no slab stuff mentioned... no, it's NOT the right stuff. You need to check out industrial insulation suppliers and ask for 3 to 6 PCF rockwool, mineral wool, or slag wool slabs. Some will sell to private individuals, some won't. You may need to call every one you can find before getting someone to sell to you, but that's what is needed. http://www.roxul.com/sw34066.asp That's what you're looking for... Steve

thanks, steve. i've sent roxul an email... do you have an idea as to what 3pcf costs per sq. ft for the thickest stuff?

Not in your area - Bryan Giles has bought closer to you, he's in the Detroit area - generally Roxul is cheaper than 703; probably around $.75 to $1 a square foot??!? I just posted a couple of things on this here http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2403 Insulation is sold primarily by weight, so the thicker (and denser) you go the more per square foot... Steve

Ok, after some more searching and no response from roxul, i found a quote for 4pcf rigid mineral wool. it comes in thicknesses of 4" for $.80/sq ft and 2" for $.40/sq ft I imagine this is what i'll need to insulate the floor... BUT the control room will be built on 2x4s and the tracking room will be on 2x6s. so what i'm thinking of doing is buying 4" boards for all around and then adding 2" on top for the control room only. However, given that the joists will be up on 1/2" neoprene, won't i need more insulation or is there a better way to go about this? how about thermafiber safb? are they usually cheaper or more expensive and would they work? thanks!!! :D

Hi, i know everyone is very busy, but a short answer yes or no to "am i on the right track" would be very appreciated as I would like to either place an order or keep looking. Thanks again!!! :lol: you rock!

I would use the thicknesses you mentioned, then buy a bag or three of standard R15, UN-faced fiberglass; cut it into strips about 6" wide, and lay it on top of your (almost) filled rockwool (halfway between floor joists) before laying the first sheet of sheathing on top of the floor frame; this will slightly "overstuff" the floor cavity, and will help damp the center section of flooring between each pair of joists... Steve

awesome, thanks! I received the 1/2" 60 durometer neoprene strips today. they are 2" thick, and 36" long. -what is the best way to cut them into 2" strips? -are drywall screws the best way to mount the pucks to the floor joists? if so would i need to drill a guide hole? -do you have any compression data regarding how many lbs it would take to compress one of these 2"x2" pucks 20-80%? thank you again, i will be ordering insulation on monday!! :lol:

Razor knife Contact cement No (check out this link for one way - http://www.johnlsayers.com/phpBB2/viewtopic.php?t=839 and this one for the math whiz way - http://www.earsc.com/HOME/engineering/T ... asp?SID=11 There are several papers at the last link, about half of which you should download and read repeately til your head falls off (only reason mine's still attached is that I've not yet found time to read any of them more than a couple times) Good luck... Steve

wow. :shock: ok i read through a lot of this stuff a few times. while very helpful to understand the concepts of sound dampening, i am still searching for information on compressing the neoprene pucks. the pucks will be 2"x1.5" (1/2 inch, 60 durometer). :arrow: how much weight will compress one puck 20%? armed with this number, i can calculate how many pucks i'll need after i calculate the weight of materials. thanks!!!

Jeff, you can actually go as low as 5% - lighter gets you longer life, heavier gets you lower mam frequency. Here's the closest to actual pounds I can offer you without your doing a bunch of experimenting - http://www.mason-ind.com/eafm_mounts.htm these round pucks have specs which I have highlighted, so you can run anywhere from 37 to 117 pounds given an unconstrained ROUND puck with an area of 1.35 sq. in. on a 1/2", 60 duro puck. change any of those values, and it's recalc time; but at least this gives you a ballpark. If you cut your pucks down in width to just under 1 inch, (0.9" in fact) and use them under 1-1/2" wide joists, then the values in the highlighted portion should work for you. I would stay somewhere in the middle, around 70 pounds per. Actually, I just noticed those pucks have holes in them; you'd need to subtract that area from the total area and recalculate, it would make your rectangular pucks narrower yet. If you need material weights, I have a doc file started somewhere, let me know... Steve

steve! this is great, thank you! :lol: please post or send me a link to the material weights! it's calc time...

Here's what I have on weights/densities so far, haven't had time to expand this much - OSB/waferwood will be close to plywood - insulation weights should be easily calculable given the density - for fluffy insulation, figure roughly 1 PCF based on nominal thickness - some will be slightly lighter, but 1 PCF should work for calculation purposes... Steve

Allrighty then! :D things are progressing along, i should have some pics together shortly. i'm working on the floor, we've cut the pucks and we're adhering them to the joists. now in order to connect the joists together, -can i use screws and a screw gun? -is this preferred over nails? -what kind of screws should i use? thanks!!!

You want your floor above the pucks to be essentially a "monolith" so regardless of using screws or nails, use construction adhesive at every joint to eliminate buzzes and rattles. IF you use screws, I'd use long "deck" screws - no pre-drilling necessary because they're slim, and they're about the only thing I'm aware of that's long enough to fasten 2x lumber together. Screws will take longer than nails, assuming power fasteners (either screw gun or pneumatic nailer) - by hand (in both cases) screws will REALLY take longer :cry: Because of the construction adhesive, either way should be fine - just remember that for nails, it's better to be standing on the material when you nail it (tighter construction), fasten while the construction adhesive is still wet, and nails should be "toenailed" (every other one slanted in opposite direction, along the joist) for more holding power. If using a nailer, finish each nail with a hammer to ensure they're "sunk" below surface, and also to tighten up the joint between flooring and frame - nailers are so fast, they don't "pull" the material up against the frame the same as hand hammering will. Multiple floor layers should be at 90 degrees layer to layer, and cracks caulked before the next layer. Don't caulk til just prior to adding the next layer, so the next layer will flatten the caulk bead and pull down tighter. Remember we're building a "monolith" here, NOT an air-separated multi-leaf barrier. Hope that helps... Steve

great, steve, thanks! for the control room: added the pucks to the frame, screwed it together using construction adhesive at the joints and added the roxul inbetween the joists. now i'm onto the same thing for the tracking room, which will be 2x6s. - when should the tyvek be applied, or do i really need it? - do i need to use construction adhesive for the first layer of 5/8" osb to the joists? - what kind of screwing convention should i use for the three layers of flooring? - and regarding this

Multiple floor layers should be at 90 degrees layer to layer, and cracks caulked before the next layer. Don't caulk til just prior to adding the next layer, so the next layer will flatten the caulk bead and pull down tighter.

then how does the roofing roll come into play? how do i attach that and do i caulk that as well? using the roof roll, the floor layers will not actually be in contact with each other. thanks again!!!!!!!!!!!!