Steico Flex / Pavaflex for sound insulation?

[Sparrowhawk]

I need to block the sound of me talking and my laugh going from my ground floor office to the room above. My plan is to add another layer of plasterboard to my ceiling, stick some dense material between the floors, and then mastic gaps between chipboard sheets before relaying the floor covering.

 

At the moment 100mm batts of 036 Steico Flex (60kg/m²) is working out cheaper per m² than Rockwool RWA45 (45kg/m²) or RW3 (60kg/m²) which is unavailable except by the pallet load. Knauf's Rocksilk products are likewise hard to find. Has anyone experience of using this for acoustic insulation?

[Iceverge]

Don't get hung up on the density of insulation for sound proofing. 

 

The main job of fluffy insulation is to dampen the reverberations or "drum effect" in a cavity. 

 

Concentrate on sealing each and every air path. Perimeter, board to board, wiring holes. Downlights are a disaster. 

 

The add some fluffy insulation for reverberation. 

 

Then add mass. Denser insulation of course helps but it's an expensive way to add those extra kgs. Standard plasterboard, soundbloc and OSB are all about the same price per kg and mug cheaper than insulation. If you're feeling really cheap sand in bags or plasterboard off cuts will all help if shoved between joists above the ceiling. 

 

Finally decouple the floors although this is more important for impact noises. Strips of carpet or rubber above the joists and resilient bars underneath. 

 

 

 

 

 

 

 

[SteamyTea]

Have you thought of resilience bars as you are thinking of adding another layer of plasterboard?

 

As @Iceverge says, density is not everything.

Sound proofing is as much to do with creating destructive interference patters for the soundwaves to interact with themselves and increasing the linear path that the sound energy travels.

The longer the path, the greater the reduction.  It is an inverse square law, so for every doubling of distance you half the intensity.

 

[Sparrowhawk]

On 13/04/2024 at 16:25, Iceverge said:

Don't get hung up on the density of insulation for sound proofing. 

 

The main job of fluffy insulation is to dampen the reverberations or "drum effect" in a cavity. 

 

Concentrate on sealing each and every air path. Perimeter, board to board, wiring holes. Downlights are a disaster. 

 

The add some fluffy insulation for reverberation. 

 

Then add mass. Denser insulation of course helps but it's an expensive way to add those extra kgs. Standard plasterboard, soundbloc and OSB are all about the same price per kg and mug cheaper than insulation. If you're feeling really cheap sand in bags or plasterboard off cuts will all help if shoved between joists above the ceiling.

 

Thanks for that. I have got plasterboard sheets ready to go to the tip. This looks like a cheaper way to dispose of them.

 

So, from top down:

• Chipboard floor (for now)
• 50mm of fluffy stuff like Rockwool Sound Insulation Slab (35kg/m2)
• 1-2 layers of platerboard offcuts between rafters, as tight fitting as I can (or sand along the edges if I'm feeling obsessive)
• Current 12.5mm plasterboard ceiling

Air paths are sealed through the ceiling, but not the chipboard floor as I keep lifting it for stuff.

 

It's funny you mention sand, I came across Quietex which is crushed limestone to pour into ceiling voids to improve acoustic performance. I thought it weird but as it's mass it makes sense.

 

On 13/04/2024 at 16:25, Iceverge said:

Finally decouple the floors although this is more important for impact noises. Strips of carpet or rubber above the joists and resilient bars underneath. 

 

On 14/04/2024 at 07:02, SteamyTea said:

Have you thought of resilience bars as you are thinking of adding another layer of plasterboard?

 

I have enough headroom in my office that resilience bars are a good shout. Ditto for putting rubber above the joists to cushion impact onto the chipboard.

 

On 14/04/2024 at 07:02, SteamyTea said:

Sound proofing is as much to do with creating destructive interference patters for the soundwaves to interact with themselves and increasing the linear path that the sound energy travels.

The longer the path, the greater the reduction.  It is an inverse square law, so for every doubling of distance you half the intensity.

 

I didn't know any of that, so many thanks. This site's an education every time!

[Iceverge]

Nice one. Can you do any kind of test before and afterwards to see the difference? 

[Sparrowhawk]

I'll be able to do qualitative testing, but havent' got anything to meaure sound levels with (unless an iPhone will do a good enough job, hmmm)

[Iceverge]

1 hour ago, Sparrowhawk said:

I'll be able to do qualitative testing, but havent' got anything to meaure sound levels with (unless an iPhone will do a good enough job, hmmm)

 

It would be fine for a comparison I'm sure 

[JohnMo]

On 13/04/2024 at 16:25, Iceverge said:

If you're feeling really cheap sand in bags or plasterboard off cuts will all help if shoved between joists above the ceiling

Our 1830s house (last house) had the rubble, stones and general building waste all shoved in there, almost no noise transfer. Lathe and plaster ceiling and thick pitch pine floors.

[Sparrowhawk]

I shoved a layer of plasterboard offcuts between the rafters. Today's assessment is it's made the sound problem worse not better 😂

 

I haven't added any fluffy stuff yet as waiting for heating engineer to do his stuff, as I don't want to risk it getting wet as he moves the cylinder.

[Iceverge]

14 hours ago, Sparrowhawk said:

I shoved a layer of plasterboard offcuts between the rafters. Today's assessment is it's made the sound problem worse not better 😂

 

I haven't added any fluffy stuff yet as waiting for heating engineer to do his stuff, as I don't want to risk it getting wet as he moves the cylinder.

 

Have to you all the air paths well and truly sealed? 

 

This is the most important bit. Putting extra mass in a stud wall with lots of back to back sockets and a door is a bit of a waste of time for example.