SuperGlass acoustic. 100mm enough?

[Super_Paulie]

Evening. 

I've added 100mm acoustic wool (SuperGlass) between the joists between the ground and first floor. The ground floor has UFH but upstairs has rads, which I hope to never use. 

Question is, is the 100mm enough to balance out the sound absorption and "slight" heat transfer I require? Deck is 22mm, ceiling is standard 12.5mm. 

 

Id rather not hear the missus stomping around to the latest Taylor Swift rubbish, but I don't want a bedroom that is absolutely baltic either. Any thoughts? Banana for scale.

🍌 

 

[G and J]

I suspect that if you generally leave the doors open that will take care of warming the upstairs.  
 

Apart from the fact that I like Ms Swift I wonder if there’s a formula somewhere that calculates sound transmittance as a product of (joist depth x frequency of dance steps divided by insulation density (lumps per m3) minus floor nail length to the power of weight of dancer in kg). 
 

Such a formula might indicate that Slimming World membership is more cost effective than further insulation.  
 

Or maybe you could lighten up and join in the dancing. Hope that helps.  
 

😉 

[Sparrowhawk]

10 hours ago, Super_Paulie said:

Id rather not hear the missus stomping around to the latest Taylor Swift rubbish, but I don't want a bedroom that is absolutely baltic either. Any thoughts?

 

There are two ways sound is transmitted through the floor: airborne sound and structure-borne sound. The insulation you've added takes care of airborne sound, so it will deaden the noise of Taylor Swift from above. However, it will do pretty much nothing to deaden your missus dancing around. To deal with that you'll need to add some kind of cushioning over the joists - a thick underlay if you're putting down carpet, or better decouple the floor deck from the joists (or the ceiling below from the joists) to reduce the sound transmission.

 

Others here have more practical experience than I do - I've been focused on airborne sound transmission.

[Iceverge]

I'm not an expert either soso anyone who has a better practical understanding of it please enlighten me more. 

 

None the less, this is the internet so I'm going to present my opinion as fact  regardless!

 

To mitigate sound transmission. 

 

1. Airpaths - lots of acoustic mastic at any joints and at the walls. Seal all gaps. 

 

2. Reverberation - A layer of fluffy stuff just to stop the drum effect. The stuff you've done is fine. Infact any more will only add slightly more mass and risk increasing the coupling effect of the floors. 

 

3. Impact noises - decouple the surfaces. Carpet, foam strips under floorboards, resilient bars downstairs. 

 

4. Add Mass. Plasterboard, standard or soundbloc or OSB is the cheapest way. Upstairs or downstairs . The more kg the merrier.

 

"Acoustic" insulation adds more mass than regular insulation but it's an expensive method of buying mass. 

[markharro]

Our floor to ceiling void is about 300mm. Our warrant grant requires a minimum of 100mm >= 10kg/m2 insulation. 

 

I have some Rockwool 100mm RWA45. Will a single layer of this give us a decent enough result? My intuition was saying add more but from what you say @Iceverge that may be counter productive? If just using 100m should I try to place this in the centre of the void leaving 100mm free air above and below the insulation?

[nod]

More than enough 

I’m only putting 50 mil between party walls on student blocks and 25 in the ceilings It just stops the sound bouncing around 

[SteamyTea]

On 28/10/2024 at 00:38, G and J said:

I wonder if there’s a formula somewhere that calculates sound transmittance as a product of (joist depth x frequency of dance steps divided by insulation density (lumps per m3) minus floor nail length to the power of weight of dancer in kg). 

There is.

[saveasteading]

1 hour ago, SteamyTea said:

There is.

Highly specialised physicists make up their own shorthand formulae to avoid repetition.

joist depth x frequency of dance steps divided by insulation density (lumps per m3) minus floor nail length to the power of weight of dancer in kg). is designated as ¿.  I hope that helps.

 

All that @Icevergesays applies. I once had to design and  build a school classroom block where they insisted on woodwork below and maths above in one area and art above maths in another (artists clomp around).

The floor structure had everything mentioned. Most memorable was the osb deck with rockwool slab on it then floorboards floating on it.

It worked well but was very deep and very expensive.

 

The cushioned topping is the crucial thing in resolving  the original question.

 

 

 

[Iceverge]

6 hours ago, markharro said:

Our floor to ceiling void is about 300mm. Our warrant grant requires a minimum of 100mm >= 10kg/m2 insulation. 

 

I have some Rockwool 100mm RWA45. Will a single layer of this give us a decent enough result? My intuition was saying add more but from what you say @Iceverge that may be counter productive? If just using 100m should I try to place this in the centre of the void leaving 100mm free air above and below the insulation?

 

 

The important thing is a gap and the some fluffy something somewhere. 100mm is plenty. Think of it's function like dealing with a splashing raindrop. It just deadens the impact and stops it bouncing about. 

 

Making sure the insulation is continuous is important, the density of it really isn't as it's only a couple of extra grams per M2 over cheaper stuff.  

 

Really really get fastidious with air sealing every gap. Once you've laid the floor. 

 

Then some decoupling if you can and then mass. Use as much as you can. 

Edited February 13 by Iceverge