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Sound Insulation for Internal Walls in Grade 2 Terraced Cottages?

Postby markwass » Fri Oct 03, 2014 10:00 am

I need some advise on a pair of grade 2 terrace cottages I own, we have put in for planning to separate the upstairs from down making a total of 4 separate units.
We need to provide sound proofing between floors and to the internal flack walls, the sound proofing to the internal walls I don't think are to much of a problem. We are thinking 50mm studs at 400cts with insulation between finished with sound proof plasterboard, please provide your recommended insulation to be used.
The floors are a little more tricky, the existing construction is 100mm joints @ 400mm cts with original 18mm boarding over and lath and plaster below. We can provide sound proofing between joists but need some sort of loose matting over, the problem we have is the council listed building consultant will not let us fix (or glue) any materials to the existing floor boards. We would in this case normally go with a floating type floor but the existing floor levels are so uneven this would not be possible. We also cannot introduce any sound insulation to the underside of the ceilings as we are very restricted with head height.
We would appreciate if you can recommend any of your products and any comments you may have.
Regards Mark
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Postby custom » Wed Oct 15, 2014 2:38 pm

Dear Mark,

If you cannot use a floating floor or bond to the floorboards then your choices are very limited. We have a product called Ecomat which is a rubber cork composite material we use as a resilient layer over concrete floors. This will take up the profile of the floor and would provide a good impact resistant layer as well as improve the airborne noise reduction, see link:
If you fix this layer to the floor then it is deemed as part of the structure and you can test directly on it. Remember, you must not have it tested with the removable final floor finish in place.

Between the joists we always use a 60kg density 100mm thickness Rockwool.

As for the party walls, fairly straight forward if you have the space. Install a 50mm frame with 400mm centres a couple of cm away from the party wall, infill with high density mineral wool and fix over the frame two layers of 15mm Knauf Soundshield with an acoustic membrane sandwiched inbetween. This is an independent wall so the improvement should take it well over the 43dB Dn,Tw + Ctr requirement when built in front of an existing wall.

As it is a listed property and classed as a 'historic' building you do not need to fully meet the figures stipulated in Part E of the Building Regs, you need to make what is deemed a 'reasonable' attempt within the restrictions and if it fails you must display the test results in a communal part of the building. Once you have decided on an option to upgrade the floor then you should run it by building control to make sure it satisfies their version of what is deemed a 'reasonable attempt'.

Regards, Martin Lee - Custom Audio Designs Ltd
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