foundation questions

Hi All I have a 40 x 40 ft x 20 ft high steel building that will be erected in a couple of months. I want to first build a control room and then the live room and iso rooms later. My question is should I beef up the foundation. For example double the rebar, use a thicker pad (6 inches instead of 4) and go with a higher stress concrete. I really do not want to rush a design but I want to get the building up before some of our local codes change I want to build a control room with 15 ft high ceilings and thick dense walls (I will need max isolation for all rooms. I am in a us airforce base f16 landing path ) and I do not want to have the foundation crumbling under the weight. any advice in this mater would be appreciated DuaneWoods

Yes, it would be wise to kick your slab up a notch -- an extra inch or two thickness, reinforcement with rebar or fibermesh (or both), and deep haunches where you intend to have heavy walls placed. Are you sure you want to do a steel building? You're not the first to propose doing so, but it's not considered ideal -- far from it, in fact. See jal's "starting totally from scratch" thread in which I think we pretty much scared him off. :roll: My recommendation is not to move one pebble until you know exactly what and how you're going to build. I understand the desire to get things moving, especially when facing possible/probable code changes, but you'll be far better served by getting your plans solid before you begin building. I guarantee you will end up painting yourself into a corner if you build the building first and then retrofit a plan. Check out studio911's "Please Help me - Building My Studio With Noise Isolation! ;)" thread. Notice how his plans change pretty drastically before he even breaks ground on his home addition. You have the luxury of building from scratch: leverage all of that to your advantage. 8) Just curious: what kind of code changes are you possibly facing? You may be better off planning and designing in accordance with those changes even before they become effective. --Keith :mrgreen:

sharward wrote:

Yes, it would be wise to kick your slab up a notch -- an extra inch or two thickness, reinforcement with rebar or fibermesh (or both), and deep haunches where you intend to have heavy walls placed.

FWIW- fibermesh does not add any strength to concrete - all it does is create a ultitude of small cracks so that (hopefully) large cracks won't form.......... however - rebar in a structural slab placed in the lower 1/3of the slab will add strength - and a mat of bar @ 16" centers in both directions will give you everything you need to stop expansion cracks from forming. I could always provide some details on how to work around columns so that re-entry cracks wouldn't form.

Are you sure you want to do a steel building? You're not the first to propose doing so, but it's not considered ideal -- far from it, in fact.

I suppose that depends on how much attention you pay to details - and to what extent you want to carry the design through....... The movie studio that Steven Spielburg so loved - the one I headed up the design team and oversaw the construction of - was a metal building with some specialites - and you can put a helicopter hovering 30 feet over the studio and not hear it inside........... SO perhaps it would be better to discuss options - and then detrmine what method of construction would be best suited....... One of the big challenges here is creating a roof with enough mass to keep the sounds of the aircratft out of the building as much as possible to begin with - and with a wood frame building that's a challenge to say the least. With a steel building it's fairly easy to beef up a little steel so that you can pour a 4" lightweight concrete on top of metal deck for your roof......... then 12" of insulation below that (held in place with wire netting) and build your room below that - and you have a 1/2 a chance........ of developing the level of isolation you need to handle air craft...... I would cosider a steel building - with a typical girt system - and then infill the frame (outside face in line with the girts) with 2x4 steel framing and 3 layers of drywall - then install the out-sulation typical with steel buildings - and then the standard steel siding on top of that.......... Then inboard of that construct your new wall assemblies insulate and minimum 3 layers of drywalll............. You end up with a lot of mass - and a very large air space......... In a case like this I would be going out of my way to contact a structural engineer and a good local acoustician to put together the optimum building - you need to take a series of decibel readings to determine what you really need to deal with from the perspective of your particular fly zone - and that is not anything that anyone here can give you in conversation. ANdit isnt just a couple of readings you want - I would not settle for anything less than one week of data - 24 hours a day - so that you could track trends - and not with a simple data logger giving you averaged decibel readings - I would want allof the frequency spectrum down to 50 Hz. Sincerely, Rod

Great info, Rod. Indeed, I was way too quick to dismiss the idea of a steel building. I guess my assumption was that the steel building was being spec'd because they tend to be quick and cheap, relatively speaking. Obviously, what you're describing is neither. :-) --Keith :mrgreen:

Thanks Sharward and Rod for your time and words. I purchased the building in 2003 to use as a office and shipping and receiving on my 1 acre property. since 2003 our buisness model has changed and the building will not be used in the same capacity. I live in unincorperated maricopa county but the city of peoria has been trying to annex us and we will be in the city and the codes are a little different and a lot more expensive. I tried to sell the building with no luck, so here I am. I feel my best choice is to pay 10k for the concrete and erection . I had no plan to use this as a studio but I have a hd accel 3 system with quality outbord gear and a ton of plugs and I am tracking in a very small controll room with some big dips @ 160hz and it is a half hour drive away. I have about 18k set aside for the controll room then as time goes by and i save more money i had planed on constructing live room. the f 16 fly overs are very random, the training schedule for luke AFB is always kept mixed with no set days. I will try to catch them and use my spl to get some data. sometimes they are so low I can hear the flaps or what ever (sounds like a cd player opening and closeing at 90 db) when they fly buy I am confused about what to do Thanks guys

I guess you have some decisions to make. One option would be to hastily plan something that you think will work for you in the long run so that you can build it before your parcel is annexed. The risk is that any errors or less-than-idealisms you create may have to be corrected at your expense later, or simply lived with, or some combination of those. Another option you have is to diligently plan your build based on your long-term needs, and then start building once you have a solid plan in place and a permit issued. The risk is that your municipality may change in the meantime and that you will/may endure increased permit or plan check fees if that happens. Personally, I'm much more comfortable erring on the side of more planning, even at the expense of possible higher permit fees. Your plan will almost certainly undergo numerous iterations between now and the start of construction if you take advantage of the opportunity. Did you study studio911's thread that I referenced earlier? That's a great example of how fluid ideas are when construction has yet to start. Bottom line, I've been here for over two years, and I have yet to see anyone post regrets of spending too much time planning and waiting too long to build. I have seen a plethora of examples of people doing the opposite though. I've even seen projects come to a screeching halt due to lack of planning, some of which I believe were abandoned completely. :roll: Planning = good. --Keith :mrgreen: