realistic isolation of Footsteps

Hi everyone, I'm in the process of designing a basic studio on the second floor of an industrial building. The plan is to build internal stud walls with rwa45, green glue and sandwhiched 16mm fire proof plasterboard as well as the same for a ceiling all with a 100mm gap to the original boundaries. I may also try to float the floor but this is unlikely as my budget is low. At the minute, the footsteps in the surrounding corridors and the doors slamming cut straight through to the room and is quite terrible when there is high traffic of people. A portion of the flooring in these corridors is old oak in some places which only makes things worse. Question is, once the inner walls/ceiling are in place how much isolation should I realistically expect? e.g. the frequency of footsteps means I shouldn't hear them once the room is sealed? will there will be a significant improvement? reason being sometimes the sound is hard to localise and I'm concerned the footfalls are transmitting via flanking too. Many thanks Rob

I'm in the process of designing a basic studio on the second floor of an industrial building

Second floor builds are much harder to do than ground floor, and are more expensive. Do you have other options?

I may also try to float the floor but this is unlikely as my budget is low.

Might not be a good idea... : viewtopic.php?f=2&t=8173

At the minute, the footsteps in the surrounding corridors and the doors slamming cut straight through to the room and is quite terrible when there is high traffic of people.

You might want to consider carpeting the corridor. That's a small price to pay, for eliminating the sound of impact noise at the source. Trying to eliminate it at the receiving end is a lot harder, and a lot more expensive!

Question is, once the inner walls/ceiling are in place how much isolation should I realistically expect?

Depends on how you build it! It might be 30 dB, or it might be 70 dB, or it might be anywhere in between.

e.g. the frequency of footsteps means I shouldn't hear them once the room is sealed? will there will be a significant improvement?

Once again, it depends on how you build the room. Footfalls are impact noise, so that is structure borne, and hard to isolate.

I'm concerned the footfalls are transmitting via flanking too.

Exactly. the air-borne part of the footfall noise is not an issue: it is the impact part that is a problem. - Stuart -

Thanks For your reply stuart, I thought nobody was going to respond! You pretty much confirmed my assumptions that it will be hard to determine until it's actually done. What I need to do is concentrate on finding the right person that can build an airtight inner room cheers

sumbody wrote:

What I need to do is concentrate on finding the right person that can build an airtight inner room cheers

What you want to do is look for someone who is involved in doing an acoustical build. The assumption that air tight is part of an acoustic build is to dismiss the >fact< that any build that is completed will be air tight. The fallacy in thinking is that somehow acoustics trumps construction, when in fact it does not. It is not even the same thing and the goal is different. The difference is sound isolation. There have been standards in place for decades as to the sound isolation between multiple home dwellings that the one side should not be able to hear anything over an approx. 50 on the STC scale, which usually winds up being a firewall that breaks the path between the two buildings in the event of fire. But the Sound Transmission Class is aimed at the human ear, not part of the musical spectrum that we deal with. So your goal is not to aim your trust in what an acoustical environment will be but what it is the structure and the building concepts involved will be since they [the concepts] will maintain a higher degree of isolation, all things being equal.