I am think of building a jam/recording room in the backyard. Thinking about something like 15'X15'
Hello gwayms and welcome to the bbs.
First off gwayms, can you tell us where you are. That doesn't tell us much, but does give us an relative idea of building codes and material sources. However, we need MUCH more information to give you valid solutions. For instance, how far away are the neighbors from each side of the "proposed" building. And how loud do you play, relatively speaking. Is it a rock band? Have drums? How about recording? Have you done much recording in the past? Is this property in the city or whats the situation?
At this point gwayms, without knowing the particulars of your location, it would be very difficult to give you precise information. This is because of possible Building codes violations as per your location and circumstances.
However, there is TONS of information you need to know regarding the methodology, techniques and materials which are used to build "isolated" rooms, BEFORE you start. RETROFITTING mistakes after the fact is almost impossible for this type of construction. So the best thing I can suggest is to read. Here are some sites to give you an overview of the necessary information needed to succeed.
http://www.saecollege.de/reference_material/index.html
http://www.johnlsayers.com/phpBB2/viewforum.php?f=2&sid=f8f186822f24bb012e5d73978154c7ca
You no doubt will need to treat the space once its built. Here are some excellent sources of acoustical treatment information.
http://www.realtraps.com/info.htm
http://forum.studiotips.com/viewforum.php?f=6
Mainly want a place to jam and not bother the neighbors or the wife.
That can be a tall order if certain conditions exist, or it could also be fairly simple. It just depends on your circumstances. For instance, if neighbors are very close(25 feet or less), or the proposed space is close to your existing home(10 feet or so), will mean a more robust solution than if your neighbors were 50' away.
Was thinking at first of building it out of cinder blocks but not sure about that and should i do a slab or what?
All I could tell you at this point is this. The BEST bang for the buck exterior wall construction for isolation is a MASS AIR MASS, two leaf assembly with a SEALED airgap, and one leaf decoupled from the other via double wall construction, or use of decoupling technigues and materials such as staggered stud, double walls, Resiliant channel, or Resiliant isolator products. Even with a cinderblock exterior leaf, you need another decoupled leaf, such as a stud frame with multiple drywall layers. This M-A-M assembly is NOT just walls, Ceilings/roofs must maintain this TWO LEAF concept with the attic being a sealed airgap and possibly a roof mass to match that of the exterior wall, or it could possibly be a weak link. Which would negate your proposed cinderblock walls. Remember, an isolated structure is ONLY as good as its WEAKEST LINK. Everything must be taken into consideration. Soils, codes, doors/jambs/thresholds, windows, roof loads, seals, and many many other things. One more thing. When you SEAL a room to make it "soundproof", you also make it....AIRPROOF. Which means ventilation is required. But then you have a conundrum. How do you penetrate an inner shell for ducting in fresh/heated/cooled air while maintaining the integrity of the TRANSMISSION LOSS of the envelope? Good question. Read thiose links and you will begin to see.....building an isolated room is NOT an EASY TASK.
And actually, given a worst case scenario, the WHOLE ROOM may need to be "floated" within the exterior envelope. Which is UNBELIEVABLY expensive and time consuming. Not to mention the PERMIT process. Which I haven't even mentioned because of not knowing your location. Even GETTING a permit for this type of construction can be a lesson in frustration if you don't understand the process OR how to correctly build.
However, in the interest of opening your eyes to the reality of SUCCESSFULL construction of an isolated room, read this thread in its entireity.
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2921&sid=368f95478e251e8cbdd17a1d2c8b7c90
If nothing else, it will illustrate a few of the concepts you need to familiarize yourself with. I can guarantee you tahis though. If you fly by the seat of your pants without getting a handle on this stuff, you WILL waste your time and money.
There are MANY MANY ways and materials that can be used to achieve the same results. The choice of materials is usually limited by budgets, skills, codes, availability and other factors such as soil conditions. As far as a slab is concerned, read that last link. It should exemplify what is required when seperating an exterior shell foundation from the interior shell slab.
At this point, I don't think you understand the implications.
fitZ
. Anyway, read those sites too. 