Author Topic: Non structural sound isolating wall questions  (Read 4315 times)

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Offline Holmz

  • Posts: 4010
Non structural sound isolating wall questions
« on: June 13, 2015, 09:09 AM »
A few years ago a treated a room to reduce sound transmission.
The psychologist is moving office and needs a non-structural wall put up.
The floor is carpeted on a concrete slab, with brick side wall and an acoustic ceiling.

Thinking of putting base plate of 35-120 (2"x5") on he floor screwed down with concrete screws every 600-mm (2').
Then the side plates of 2x5 screwed to the brick in 3 or 4 places.
(Stuffing some open cell foam between the brick mortar gaps behind the vertical uprights.)
Q1> Does this sound proper?

Using 2x3-1/2 (35x90-mm) to hold each sides drywall with an air gap, so the uprights will be staggered between the inner and waiting room walls.
A door will go in between, which will be reused from the previous office. This has a falling seal that drop upon closure to seal the air gap under the floor, and worked well in the past.
I am thinking of scribe-transferring the brick/mortar patter onto a vertical "skirting board and cutting that with a jig saw to minimise the air gap on on the sides.
Q2> Does that sound reasonable?

I believe I have the rest of it worked out as far as dampners on windows and weather stripping on doors to help isolate the noise and sound. Most of the effectiveness was just sealing the power outlets and around the ceiling tiles to get rid of any air gaps.

Any general thoughts are welcome as I am not generally a wall installer, and it seems that all the local tradesmen are fully booked.

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Offline DirtyOldMan

  • Posts: 31
Re: Non structural sound isolating wall questions
« Reply #1 on: June 13, 2015, 09:59 AM »
Interesting project. Rather than reinvent the wheel why not use an engineered system. E.g. CSR soundcheck or similar. They have isolated mounting hardware which has a huge influence on sound transmission.

http://www.gyprock.com.au/Documents/GYPROCK-949-Strata_Wall-201407.pdf

Mind you effective acoustic insulation will not be cheap.

Offline Jak147

  • Posts: 113
Re: Non structural sound isolating wall questions
« Reply #2 on: June 13, 2015, 05:40 PM »
 the best advice I received regarding the reduction of airborne sound, (not impact transmitted) is that mass is you friend, I would use a double layer of sound check board each side with staggered joints. As far as air gaps, treat sound like water, anywhere water would pass sound will 'leak' too. There are acoustic sealants available, looks like painters chaulk but expands slightly.

Offline demographic

  • Posts: 548
Re: Non structural sound isolating wall questions
« Reply #3 on: June 13, 2015, 05:45 PM »
Worth downloading British Gypsums Big White Book as it contains masses of information regarding soundproofing.

Offline Holmz

  • Posts: 4010
Re: Non structural sound isolating wall questions
« Reply #4 on: June 13, 2015, 06:51 PM »
I found a Boral pdf that agreed with my sound engineering book.

I'll look over the the CSR with a coffee in hand.
There was a fellow in QLD selling green glue which is an elastomer to use between layers of gyprock.
As most of the sound was 'flanking', and it was low enough, it was not used previously.

Off the coffee machine...

Offline rizzoa13

  • Posts: 587
Re: Non structural sound isolating wall questions
« Reply #5 on: June 13, 2015, 09:13 PM »
I think your on the right track decoupling the walls. Best option may be to build a freestanding 2x4 walls 1" in front of the current wall and tie it into the ceiling joists instead of to the brick wall. Same idea as a split wall for insulation purposes, you decouple the wall systems and heat cant transfer through as well, same with sound.

Offline Larso

  • Posts: 128
Re: Non structural sound isolating wall questions
« Reply #6 on: June 13, 2015, 10:46 PM »
I recently completed a home theatre set up and found this both an interesting project along with one difficult to get just right.
There is conflicting advice available on almost every aspect of sound proofing/retention while the general concepts are well defined.
Some things i think you should consider are both high and low frequency sound and then the echo or suound quality in the space in which the sound is retained.
Any penetrations for power points or light fittings etc,along with doors and windows are areas for special attention.Air gaps in stud walls and decoupling components is also something you should look into.
I used green glue for the first time between two layers of firechek gyprock (staggered joins) along with sound batts in the cavity and can confirm it does work as advertised.This i believe is a US product originally so someone here may be able to give you some more info.
I had a client who was really into this subject so essentially i was following directions but did pick up plenty of useful info for future jobs, good luck with your project.

Offline Holmz

  • Posts: 4010
Re: Non structural sound isolating wall questions
« Reply #7 on: June 13, 2015, 11:06 PM »
I recently completed a home theatre set up and found this both an interesting project along with one difficult to get just right.
There is conflicting advice available on almost every aspect of sound proofing/retention while the general concepts are well defined.
Some things i think you should consider are both high and low frequency sound and then the echo or sound quality in the space in which the sound is retained.
Any penetrations for power points or light fittings etc,along with doors and windows are areas for special attention.Air gaps in stud walls and decoupling components is also something you should look into.
I used green glue for the first time between two layers of firechek gyprock (staggered joins) along with sound batts in the cavity and can confirm it does work as advertised.This i believe is a US product originally so someone here may be able to give you some more info.
I had a client who was really into this subject so essentially i was following directions but did pick up plenty of useful info for future jobs, good luck with your project.

Thanks Lars
I pass your name onto a friend in Googong if he is doing a such a room... I don't think he is... But maybe??.

It is a psychologist's practice room, so many of the concepts are the same. However echos and low frequency modes etc are not of primary importance.
Just having the conversations inside stay to stay inside, in the outside noise staying out is also helpful... Which happens together unless there is some sort of a 'one-way sound flap'.

I think I will bang together a big boxy "muffler" for the A/C inlet/outlets this week.

With respect to putting up the wall in an existing room, what do people use to attach them to the existing floor and walls?
Just screw into the bricks with the Hilt bolts?

Offline Larso

  • Posts: 128
Re: Non structural sound isolating wall questions
« Reply #8 on: June 13, 2015, 11:19 PM »
Given it is essentially conversation noise levels just use whatever you normally use.I would use Ramset Dynabolts straight into the floor and wall.
Two layers of 16mm Firechek board (this is more dense than the commonly specified 10mm sound board so therefore better)with staggered joins and a bit of attention with the penetrations will probably be all you need to do.
I used a solid hardwood exterior door with a special draught/noise sealing system on my job as the internal doors available now are not much better than a bedsheet in retaining noise.

Offline Holmz

  • Posts: 4010
Re: Non structural sound isolating wall questions
« Reply #9 on: June 14, 2015, 12:07 AM »
Given it is essentially conversation noise levels just use whatever you normally use.I would use Ramset Dynabolts straight into the floor and wall.
Two layers of 16mm Firechek board (this is more dense than the commonly specified 10mm sound board so therefore better)with staggered joins and a bit of attention with the penetrations will probably be all you need to do.
I used a solid hardwood exterior door with a special draught/noise sealing system on my job as the internal doors available now are not much better than a bedsheet in retaining noise.

As there is no "like" button on this forum... -->  [thumbs up]
I'll screw it down as suggested.

Copy the info on the door. I am pulling out the existing door which was solid and uses something like this (but a different brand): http://www.hafele.co.uk/shop/p/seals-for-glass-doors/kg-s-door-seal/66205/8436

It has a scissor mechanism the pushes it down just as the door closes and it was effective in making it gapless (non-flanking).
Then I will reinstall the old (non-solid) door on the office that is being vacated.

For thread completeness, the Green-Glue site: http://www.greengluecompany.com/[url] and also in "/products". I forget who the Au distributor was but it was in QLD.

Offline Holmz

  • Posts: 4010
Re: Non structural sound isolating wall questions
« Reply #10 on: June 15, 2015, 04:18 AM »
Has anyone built a HVAC duct muffler?

Thinking of something like this:

To bring the AC return from the waiting room to the consult room.
Ideally in a long cabinet looking box that is open on the bottom in the waiting room, and shoots through the wall from a grill into the consult room. So maybe 8' (2400-mm) high with 6-10 baffles in it to suck out the high frequencies.