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Acoustic insulation Vs loft roll?


CH_18

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I must have read nearly every post on here regarding sound insulation and I'm still none the wiser.

 

In our timber partition walls (89mm CLS) I was planning on filling with 75mm Isover acoustic roll or RWA45 then sound boarding both sides. I've since read on here that the denser acoustic stuff has no real benefit compared to normal loft roll? There was a link to some study posted here which showed the results. 

 

Is the denser acoustic stuff worth the extra premium?

Also does anyone know of a cheap place to get some? My BM only stock 100mm and 50mm non acoustic, just loft roll 🙄

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12 minutes ago, CH_18 said:

since read on here that the denser acoustic stuff has no real benefit compared to normal loft roll? 

There is real benefit. Especially as some loft roll is very loose and sparse.

That doesn't sound like much of a bm. They will either get it in for you or you must try elsewhere. Wickes will have it too.

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Loft insulation will effectively do the same job acoustically but should not be used as it does not have the correct mechanical properties to be used in a vertical application. Additionally Building Regs ask for a minimum density of 10 kg/m3 most loft insulation is probably a bit lower than this. Beware as denser does not equate to better acoustic performance once installed!!

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Loft roll tends to slump, accoustic roll is much stiffer and doesn't.

 

I just use Rockwool Flexi and normal 12.5mm plasterboard, you don't hear much of anything through the the walls. Without the plasterboard on, but with Rockwool in place, the house was totally silent.

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1 hour ago, ADLIan said:

Beware as denser does not equate to better acoustic performance once installed!!

Keep compressing the rockwool and you'll get a board. The manufacturers have all the figures  and they are genuine.

What you are proposing will work for air-borne sound but not for impact sound.

Have you considered resilient bar?

Pay attention at the perimeter too.

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Loft insulation won’t do the same job 

25 mil of acoustic will out perform 100 mil of loft insulation 

I would also use a maximum of 50 mil on your setup Which will leave you a clear void 

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2 hours ago, JohnMo said:

Loft roll tends to slump, accoustic roll is much stiffer and doesn't.

 

I just use Rockwool Flexi and normal 12.5mm plasterboard, you don't hear much of anything through the the walls. Without the plasterboard on, but with Rockwool in place, the house was totally silent.

Same approach here and sound only tends to transfer up the hall and come in via any open doorways than through walls. We did have 9mm OSB for racking on most walls though. 

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1 hour ago, CH_18 said:

anyone used URSA acoustic roll

Never heard of it, so I've looked them up and it seems to be a big company taken over by an even bigger one, and only recently on the UK market so it should be ok.

 

My only doubt on insulation was because one product (I won't give the manufacturer here) turned out to be ultra loose, and I never bought it again.

Choose any that is stated to be for the purpose, you'll never know if another might have been better or worse.

But mostly, build it well.

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2 hours ago, CH_18 said:

Thanks gents, appreciate the advice

 

Has anyone used URSA acoustic roll? Seems like a middle of the road option at 22kg density?

I’ve bought URSA acoustic but have not fitted it yet 

I did get it at a really good price.

I have heard it on good authority that’s it’s much nicer to use than Isover as it’s a bit stiffer so for ceilings it will stay up between the joists when you go to fit the plasterboard. 

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21 minutes ago, Chanmenie said:

I’ve bought URSA acoustic but have not fitted it yet 

I did get it at a really good price.

I have heard it on good authority that’s it’s much nicer to use than Isover as it’s a bit stiffer so for ceilings it will stay up between the joists when you go to fit the plasterboard. 

 

Yeah looks like a decent middle of the road option, nearly half the price of RWA 45.

 

Where did you get yours from @Chanmenie?

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I used Ursa acoustic roll. Very good price from Profile Store. I also used two bags of Knauf whilst waiting for the Ursa delivery. I would say that it is very hard to choose between the two products. The Ursa may have needed a little more fluffing before it reached its true depth, but it is strong and holds itself well. 

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Ok thanks for the advice

 

What about in the ceiling between joists? I suppose because the insulation is laying flate it doesn't need the structural properties of the acoustic stuff so is normal loft/mineral roll on here? Looking to put in 150mm.

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