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princeplanet 2nd August 2019 05:18 PM

Recording Studio / Audio Post Production Hub on level 7.
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This build will be on the 7th and top floor of an office building. The level 7 neighbours will be other production suites or photographic studios, and I know all these people and they assure me they will be tolerant of noise leakage through their walls. They know what to expect and have been getting a taste on weekends ;), ie rock drums and loud bass amps etc in untreated rooms!...

But it's level 6 downstairs I'm concerned with as I have a lawyer directly beneath me! The existing slab is 125mm reinforced concrete on bondek and fortunately the steel beam support provides for a live load of 650 kg/m2 on the slab. In the attached diagram you will see the single dashed lines which indicate where the supporting beams are under the slab. The Structural Engineer assures me I can have a floating floor of 112mm compressed cement sheets at 187 kg.m2 raised up 100mm atop proper engineered isolation mounts. The grey area indicates the proposed floated floor. The single dashed lines indicates where the beams are. I am told the walls need to be built within 400mm from the centre of these beams and all walls comply except the south inner leaf wall in the white room which will be the control room. As this room will not have a floated floor, nor an inner ceiling (at least to begin with), I expect I'll be allowed to have this wall here as its not a supporting wall. Also, the wall density can be less for this room, in fact, I'm hoping for 35kg/m2 for these walls and 60 kg/m2 for the floated studio walls. The studio might also have a 35kg/m2 ceiling built upon the walls sitting on the floated floor.

So if I match the wall density with all doors and windows, my question is can anyone calculate whether I actually need all of the 60kg/m2 for the studio inner leaf (the outer leaf averages around 30kg/m2 with a minimum air gap of 100mm)? Also, will 35kg/m2 for the inner leaf ceiling be enough to not trouble people beneath me? I have an acoustic consultant that has advised that even only 35kg/m2 will be enough for these walls, but Soundman2020 on another forum thinks that 60kg will be necessary at the very least.

At this stage I still have not been given the max load I can have for the walls upon the beams, and in case the verdict is negative, then I need to lessen the load. Here's my main question then- If I'm only allowed say only 35 kg/m2 for these walls, can I still improve the TL going through the floor outside these walls if the bottom metre or so of the walls are 60kg/m2 and the top 2 metres only 30kg/m2? Or should the whole wall top to bottom be consistent at 35kg/m2?

Surely the higher up the wall, the greater the gap between the wall surface and the floor surface, which is presumably why the ceiling need not be the same density as the floating floor. My acoustic consultant showed me a spreadsheet explaining the maths behind this concept, but I'm not convinced as I have never come across this information before on forums or in books.

Any thoughts on this out there?

princeplanet 2nd August 2019 05:48 PM

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... Thought I'd add another diagram of what I was asking in the above post to show how the bottom of the inner leaf might relate to the rest of the structure.
Presumably any door in this wall would also have something like a layer of lead in the bottom 3rd to be commensurate withe the wall density down there...

princeplanet 6th August 2019 07:32 PM


princeplanet 9th August 2019 03:43 PM

Is the question too hard? Or just too boring? confoosed ...

JayPee 10th August 2019 06:02 PM

Lot of details...hard to tell you what to do exactly on a forum. Should be addressed to a pro IMO. Many great guys here... kfhkh