Building Inspector gives greenlight!

Had another chat with the county Building Inspector (referred to as B.I. herein)! I told him about the change in plans and double walls will be added! The B.I. basically said that my "Floor Trusses" will handle the weight and as long as the second wall is not a load-bearing wall and the trusses are supported with the main wall......everything is "Coochie-Crunch" {down south slang for alright}! I asked him about making sure it was safe under Commercial standards rather than Residential? He stated that unless I used concrete & rebar on the 2nd floor I was OK! The B.I. made the comment, "It's no different than a house having different walls for different rooms! Those rooms all have walls...don't they?" I shrugged my shoulders and said, "Well yeah!" I still plan to implement.... at least the 55 gal. drum of "Green Glue" between the Tracking Rm. & Vocal booth 1 & 2. I lucked out and found plenty of Owens Corning 703 RFB in Charlotte, NC which is about 40 minutes away! He quoted me $48 USD a bundle.....not sure how much a bundle is quantity-wise, but I don't need it right now and he said they keep plenty in stock! I didn't walk away totally happy! The down-side is the fact that I'll have to crawl under my structure and dig 2 footings for 2 more piers (12" below grade! Fill with concrete--> then blocks---> then 2 short girders to support the floor. Why??? Because where I plan to put the stairs....there has to be an opening between floors, right? This means the floor trusses will not come all the way across the 24' span for the opening! At the point where the short trusses will run, there must be a wall for them to rest on. That makes this wall a load-bearing wall, which must have support all the way down to the footing! Yes, you guessed it! There were no footings or piers at the point I needed them to be! Well unless I wanted stairs 8 ft wide! Looking at this plan.......the trusses will span from left to right! Oh well.......Safety before music!

Very interesting and (other than the craw-digging you're going to have to do) encouraging news, 14K! I will say, however, that the "extreme" example your inspector cited (" unless I used concrete & rebar on the 2nd floor") is actually not out of the realm of what would have been the possibilities. There is no shortage of discussion on this forum about the pros and cons of floating a concrete slab for isolation. Floating a concrete slab generally requires two concrete slabs of up to 6" in thickness for a single floor. :shock: So, OK, we know you don't have that option. (Although, truth be told, if you had known ahead of time that it would be the best option for your situation, you very well may have chosen to go that route, and thus you would have engineered your building differently.) So, the ultimate (and difficult and expensive) solution is not possible now. But what is possible exactly? Also, although you won't necessarily be adding "roof" load bearing walls to your design, you very well may have load bearing inner walls in your space, if you mount heavy ceilings on those walls. With your (presumably) vented attic, you would need to have two ceilings in order have two dense, air-tight leaves overhead. The roof would act as a third leaf, with the air inside the act acting the spring between your upper ceiling and the roof, but I would think and hope that the vents in the attic, along with its large volume of air, would mitigate the dreaded third leaf effect. At any point did you tell your inspector that these extra walls you're contemplating (and the ceilings they'll probably support) have multiple layers of drywall on them (like, three or four on each side)? 5/8" drywall weighs about 2.3 pounds per square foot. A small wall that is 9' x 10' (90 square feet) with four layers of drywall (9.2 pounds per square foot) weighs about 828 pounds for the drywall alone (i.e., not counting framing lumber, or any ceilings)! (Obvioiusly, using two layers of drywall with Green Glue would cut the weight in half.) Now these walls may not seem very heavy when you calculate the total amount of square footage of room space they'll cover, but when you consider the fact that their footprints will measure over 150 pounds per square foot, you cannot afford to assume that the trusses and the rest of the framing will hold. You have to prove it, even if to nobody but yourself (if the inspector doesn't care or doesn't think he has to care). So, in short, while I'm glad your inspector is giving you the thumbs up, it seems to me that he may have given you his approval without all the facts necessary to do so. --Keith :mrgreen:

Geez!!!!!! The only thing I can think of..... at this point to strengthen the floor would be to place the trusses 12" O.C. They're rated for 24" O.C. for the 24ft span, So that would actually double the load capacity for any future isolation treatment! Hummm! The only question that comes to mind....{and I'm sure you guys have had the same thought at one time} is when all of this treatment is done, would I have been able to tell the difference if I had not applied all the treatment? I mean with the naked ear, not some scientific measuring tool? I plan to do it right the first time, but can't help from wondering? Okay, back to the inspector's office....I go! Thanks for advice and the time you take helping me along......it's all taken in & appreciated!

Your goal should not necessarily be to increase the strength of the building to some kind of maximum state and thus be assured that whatever you build on/in it will hold. It should be to measure and calculate everything so that you know how much it will weigh, and then verify that the structure will hold. If that verification fails (it probably won't -- but just in case it does), then you'll need to either lighten the load or increase the strength. Only cross the unlikely "it won't hold" bridge when and if you actually get to it (on paper, of course). Analogy: You're going to drive from point A to point B and there is noplace to fill your gas tank along the way. Bad plan: Fill the tank before you leave and assume you'll make it all the way across. Good plan: Determine actual engine efficiency in MPG. Determine capacity of tank. Multiple capacity by efficiency for estimated maximum range. Determine distance between points A and B. Verify that distance is less than range. If yes, fill up and drive. If not, address challenge (carry extra gas outside of tank, use more efficient car for trip, etc.). Makes sense? --Keith :mrgreen:

14K, Hey remember above and beyond anything your asking BI, which he approves or doesn’t, or anything we on the forum say, THE MOST IMPORTANT NUMBERS YOU NEED ARE: PSF (pounds per square foot) dead (structure weight) and live (people and gear) load that these truss/joists will have. This is why Sharward is repetitively and rightfully posting about weight. :D With the PSF dead and live load info (I believe you were waiting for this info from engineer?) you can then add up your structure weight for dead load (how much structure mass you can use for isolation and acoustics) and your live load (you are going to need to get a good estimate weight of your gear, albums, & amount of people that will be on 2nd floor at once) and then proceed to how you are going to isolate Moving from 24” OC to 12” OC may not actually double the load.

would I have been able to tell the difference if I had not applied all the treatment

YES you will, and as you build each layer, you can do “by ear” tests by cranking a boom box inside the room and go outside to listen, take a note of what you here maybe even playback the same track at each test. Also you can get a DB meter from Radio Shack to aid your testing. And could I ask that maybe you try and keep posting your questions, pics, info and explanations of how you’re coming to make your decisions to a single thread. I don’t think this forum has seen a 2nd story sound isolated room done successfully built on wood frame. How ever successfully you accomplish sound isolation in your situation will serve as a learning tool for future forum users, just like you and I both have learned from previous threads of forum users. Marc

The gas example makes "Perfect" sence!Another option that was mentioned to me was precast concrete walls (exterior walls). They basically attach down to the footing and span to the roof. All of the openings are pre-measured and cut out prior to being installed! "Thin Brick" can be applied to the concrete! We're looking at an estimated $42 USD per linier ft. I do desire to have good quality exterior walls.......and I hate vinyl siding! So I'll do more research on that cost versus do it other ways! Back to reading.....and playing "Catch-Up"

Great post, Marc -- thanks for the support and for introducing those important terms that I neglected to bring up (dead load, live load, etc.). 14K, forget about the precast concrete walls at this point. You're crossing the bridge before it's time! Remember, it's your job right now to do all the math to make sure you're not going to overload with your current plan. If, after doing the math, you discover that you are at risk of overloading, then you can look at ways to make a stronger building and/or figuring out how to lighten your load. Marc makes an excellent point about yours being unique in that you're building a new construction upper floor isolated space. I think he may be correct in stating that yours is the first example of that. So, while there is a lot of information available here from which to learn, your thread is probably going to be cutting a new pathway in that specific information space. Many of the principles of existing projects can certainly be applied to yours, but you have to be careful not to apply them without keeping your "upper floor context" in the very front of your mind when doing so. I'll bet you'll never look at a building the same way again, huh? 8) --Keith :mrgreen:

I'm back with a question of all questions I've asked!!!! For my studio application.....I doubt seriously that I'll use a microphone for any reason other than vocals! All the gear I'll use are electronic instruments such as keyboards, midi sequencers, turntables, maybe Vdrums! The point I'm making is all gear has a direct input to the recording source selected! I won't be mic.'ing acoustic drums, grand pianos, acoustic guitars, etc! I understand I'll need a treated space for mixdowns and such! So the question would be.....should I just worry about the vocal booth and create a mixdown room.........or should I continue the plan of treating the whole structure???? Just curious.....I'm new to the studio design world!!!! I'm seriously considering just putting a roof on the existing framework of the 1st floor.....then having a 24'x28' concrete slab poured in the back of the existing structure and starting from scratch! In the long run....I'd rather be sure & happy than spending countless dollars trying to make the second floor sound right! It's not too late....I've got about 3.5 acres to work with, so land is not a problem!

Sharward

14K, forget about the precast concrete walls at this point. You're crossing the bridge before it's time!

I agree.......see above post! So many decisions to make!!!!

14K

I'm seriously considering just putting a roof on the existing framework of the 1st floor.....then having a 24'x28' concrete slab poured in the back of the existing structure and starting from scratch!

WOW!!! What a change in the game plan. That will undo the need for countless SWAG’n (Scientific Wild ^SS Guess'n) and allow you more options. Hopefully it would be cost effective too. You'll also have the opportunity to create separate isolated slabs for CR and vocal booth. 8)

So the question would be.....should I just worry about the vocal booth and create a mixdown room.........or should I continue the plan of treating the whole structure????

Yes worry about the isolation between vocal booth and CR BUT… How much isolation you want to the outside world is up to you, which should mostly depend on those neighbors. You may want to (if you haven’t already) talk to them to get a feel if they would call the cops or not on you for sound disturbance. :!: Your county (or city) should have a sound disturbance bylaw with an un-weighted dB level (A weight on Radioshack meter) at your properties edge for various times of the day. It could be from 50 to 65 dB's or something like that. :!: It may be worth it to get a db meter from radio shack, and go over the STC and LF TL stuff I mentioned in your other thread… it’ll be hard to pick an isolation goal with out the meter and the knowledge. :!: You can also take notes on what others on this forum are doing, Sharwards looking to isolate 115 dB’s. Me I’m looking to only isolate 85 dB’s or so but I’m willing to turn down at night. My goal is STC 65 and LF @ 50 hZ a TL of -30dB’s. AND I'm not set on that, as I build and test I may add more mass if I'm not happy. :roll: BTW 85dB is the recommended listening level for mixing. Anything more your ears should get fatigued and you just can’t hear correctly after hours of working. 8) I do regularly abuse my ears at live gigs and when I can, I wear ear plugs. I have Tinnitus, a big old ringing in my ears that will never go away and I can ignore until I lay and down to go to sleep… I am so looking forward to my room for two reasons 1. I won’t have to crank it to really hear it and 2. I will absolutely and clearly be able to pick out the pitch of the ringing in my ears. :wink: Be careful with your ears. If you have an acoustically well built room… as far as I can tell by many, many users of this forum who have completed room acoustics you may not have to crank it that loud. You had a question on your other thread about feedback from CR monitors to vocal booth mic I’ll borrow something from Rods book… there is no such thing as a sound proof room how ever there are rooms we can create with a great deal of sound isolation. I live near the Space Center, there is no way I can sound proof my room from a rocket launch less then 10 miles away or the sonic boom when the shuttle comes back in, I would still feel and hear the “bass” no matter what. If you build those walls correctly you could get feedback from vocal booth to CR but it would be a bass frequency feedback and the music would have to be so loud your ears would be bleeding. :shock: AND everyone have a good weekend. I'm out of town for a gigs and a crazy family re-union till Monday. Go to finish packing. Marc