Hi All,
Looking for some desperate help. I have built a decoupled wall in my UK home. The existing wall is thermolite blockwork with dot and dab plasterboard/drywall (did not remove prior to construction, was told it would act as another sound barrier). I left a 1 cm gap from that and built:
- 50 cm metal studwork filled with Rockwool sound insulation slab
- ikoustic muteclips (sound insulation clips) with furring channel
- 19mm plasterboard/drywall
- green glue
- 15 mm plasterboard/drywall
The wall itself is working great with airborne noises, but with structural impact noises coming from either my neighbours or in the room, there is a bassy boom at around 35-40 hz. So even light footsteps from next door, my wife running on the treadmill etc. can be heard quite clearly as boomy sounds in the room. The neighbours have complained that they hear subwoofer like sounds when we walk/run on the treadmill as well. The wall has made these sounds worse than prior to construction. My question is pretty much what could be causing it? And if I do need to tear the wall down and rebuild (£1000 down the drain), how do I avoid this problem in the next build?
Thanks for reading!
Decoupled wall acting as a subwoofer
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ManuD
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- Location: London, UK
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Gregwor
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Re: Decoupled wall acting as a subwoofer
Welcome to the forum!
Please completely fill out your profile as per the forum rules.
If you really need to isolate things better, the cheapest route would be to build proper inside out room using all of the techniques regularly discussed here on the forum.
If only certain things are an issue (such as the treadmill), then you could build a sort of de-coupling platform for the treadmill such as this: For noise producing items such as furnaces that are a constant weight but shake and cause structure borne noise, you could install properly sized Sorbothane.
Greg
Please completely fill out your profile as per the forum rules.
If you check out the Transmission Loss Calculator you can see that different combinations of surface densities and air gaps (in your case 1cm) will isolate at different frequencies. The "F0" value represents the resonant frequency of your wall. The sources at F0 are amplified.My question is pretty much what could be causing it? And if I do need to tear the wall down and rebuild (£1000 down the drain), how do I avoid this problem in the next build?
If you really need to isolate things better, the cheapest route would be to build proper inside out room using all of the techniques regularly discussed here on the forum.
If only certain things are an issue (such as the treadmill), then you could build a sort of de-coupling platform for the treadmill such as this: For noise producing items such as furnaces that are a constant weight but shake and cause structure borne noise, you could install properly sized Sorbothane.
Greg
It appears that you've made the mistake most people do. You started building without consulting this forum.
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endorka
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- Location: Falkirk, Scotland
- Contact:
Re: Decoupled wall acting as a subwoofer
I made a platform to this recipe with green glue between the layers, and it works incredibly well for attenuating impact noise to adjacent rooms as well as those below.
The plywood and MDF boards come in sizes of 2440 x 1220 x 18mm in the UK, so perhaps for a treadmill you could use just three in total to make a platform 1220mm wide. It would certainly be very cheap to try, and might keep your neighbour happy, although you will still hear them of course.
My knowledge of the mathematics of this is poor, but perhaps with a relatively controlled mass and purpose such as a treadmill it might be possible to optimize the isolation though choice of mass and deflection of the insulation?
Cheers,
Jennifer
The plywood and MDF boards come in sizes of 2440 x 1220 x 18mm in the UK, so perhaps for a treadmill you could use just three in total to make a platform 1220mm wide. It would certainly be very cheap to try, and might keep your neighbour happy, although you will still hear them of course.
My knowledge of the mathematics of this is poor, but perhaps with a relatively controlled mass and purpose such as a treadmill it might be possible to optimize the isolation though choice of mass and deflection of the insulation?
Cheers,
Jennifer