Soundproofing, A whole load of options and never enough money!




The more I read, the more confused I get....Any help and direction you can offer would be appreciated :thumbsup:

I own a 50's detached house. Solid in build but due to late nights on Call Of Duty & in preperation of Modern Warfare 2, I need to soundproof to try not to wake the family !!!

I'm due to decorate the bedrooms and am going to be replacing the carpets upstairs so will use Cloud9 or similar to underlay.

I also plan to put some sort of insulation between the joists to reduce the racket from below. Depending on the threads I've searched, I've read insulation will make a great deal of difference and I've read its almost a waste of time/money/effort. So now I'm confused!!

Will Insulation between the joists help? Are there any rules to follow? Should I just buy expensive accoustic mineral wool or are there cheaper products in Wickes/B&Q that are actually very similar in result?

There are a plethora of options of which you won't know the result until you've spent your hard earned cash....

I don't want to spend a fortune but do want best bang for buck. Can you please advise.

Thanks in advance & apols for long thread.

Stace :)

Ted White

Established Member
Insulation will do something, but in coupled framing will not do as much as you'd probably like. There's no reason to consider anything expensive beyond standard fiberglass or commodity mineral fibre. Anyone who says otherwise needs to review the independant lab data. Avoid foams.

You would do well to look at increasing the mass of the ceiling below with another sheet of standard plasterboard. Thicker is better. If you could add mass to the upper floor, that would be a plus.

To gain more isolation, consider decoupling the new ceiling drywall from the original wood floor joists.

Ant time there are two or more laters of mass, you can consider using a damping material in between them.


Hi Ted,

Thanks for the reply, unfortunately I won't be in a position to add mass the the ceiling below. My missus thinks I'm wasting my time as it is. If I tell her I'm ripping down the coving for additional plasterboard and then putting it back she probably cut of my jewels!

I'm pretty much limited to something under the floorboards. Should I be looking for something around 60 kg/m3 25-100 mm (taken from a rockwool website)?

Should I go the full 100mm or should I leave a gap under the floorboard so it doesn't touch?

Thanks again :)

Ted White

Established Member
Hi Stace,

Don't go any lighter (less dense) than that. Also, no more than 150mm or whatever is close to that over there. Additional insulation paradoxically will only give very minimal increases in isolation. 150mm should be your speed limit.

Low to medium density insulation installed properly will not allow conduction to occur.


OK Thanks.

I assume they are 100mm joists so was expecting to put no more that 100mm between the joists. I'll go with the 100mm and get as dense as possible.

Any mileage in putting the rubber underlay I'm taking up, under the insulation (on top of the plasterboard ceiling below)?

Ted White

Established Member
Unless I'm missing something, I would have to assume youe ceiling framing is a lot more than 100mm. More like 250-400?

Again, keep the density moderate. Just ask for standard thermal material. Better if you don't mention the word "acoustic"

I would not recommend doing anything to the plasterboard below. Too much risk of creating a repair job below.

Do you have little rubber isolators over there? That could slip on the tops of the existing framing? If so, they could provide some much needed decoupling for relatively low cost. On top of them, add layers of standard plywood, etc.


Standard Member
Hi Ted,

Any reasons why we should not use dense material for the insulation between joists?

I was thinking of doing soundproofing my ceiling for reducing impact noise (footfall, high heel noise etc). Not so much for airborne noise as I can hardly hear any music, conversations etc. I'm not sure of the type of structure in my flat aside from it has timber floor system. Should I worry about flanking noise?

To be honest, I would really like to have assurance that the work I'm about to do can really be effective. I know it's not gonna be totally removing the noise but any improvement will do.


Ted White

Established Member
Dense materials don't allow their surface area to be exposed to the soundwaves. The insulation provides added resistance = increased friction = conversion of the energy to thermal.

Also, dense insulations can conduct vibration.


Standard Member
Thanks. Any idea which material is suitable for that? I was thinking of using mineral wool.

Also what do you think about resilient bars? will they work for impact noise.

Sorry to keep sending questions. I just want to make sure if they wil work.

Ted White

Established Member
Mineral wool, mineral fibre, fiberglass, cellulose, etc are all great. Simply avoid the "high density" offering of any of those and you'll be fine.

Resilient bars can work in theory. We don't ever spec them, however. Here in the states there is no single standard for its construction. Some is 20 gauge, some 25, some in between. Some are slotted for flex, some are solid, some have holes.

This method of decoupling is effective if the steel can act like a spring. Since there's no manufacturing standard, the net result is that you have no idea if the resilient channel is too stiff (no spring) or too loose (no spring).
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Established Member
I've just finished a 'soundproofing' job in my kitchen where I have a pair of 8" in-ceiling speakers.

I used SpaceLoft glass mineral roof insulation folded in half and shoved up in the rafters. Focus are doing a 2 for 1 on these and, in my view, its higher quality than Rockwool. That was the easy bit.

I also did some experimenting with high density wood fibre board (normally used under laminate floors to dampen sound) and Dynamat Extreme (normally used in cars to reduce panel vibration). Basically I glued two strips of wood fibre board together to create a double layer and cut it to fit in between the rafters. I then applied the Dynamat Extreme over the top. I then glued the wood-fibre side to the underside of the floorboards above. I used 'No More Nails' and its a very good and secure fit. I overcut the Dynamat enough so that I could seal the edges where the wood fibre meets the rafters so that there was a good seal.

After all of that I then added the SpaceLoft wool. I did take care to not let the insulation to totally cover any electrical wiring.

To test out its effectiveness I did one speaker and then got the wife to stand upstairs and to tell me when she could hear music. Suffice to say there was a significant reduction in volume upstairs from the 'soundproofed' speaker.

Now - and this is a caveat - I may have gone overboard with the whole fibre board/dynamat combination and so I would recommend that you try loft insulation first and see if that gives you the effect you need.

Oh, and finally, if you do want to look at the Dynamat route beware it is pricey. There are some good quality UK-manufactured alternatives on e-bay such as SoundX which is a bitumen/butyl/aluminium mix (i.e. similar to Dynamat) at half the price.

Good luck! Let us know how you get on.

Dark Eyes

Standard Member
Hello folks,

I am about to get the upstairs re-carpeted and was wondering if putting some insulation under the floorboards will make a significant (for the effort and outlay) difference in sound levels from the lounge below.

At the moment, I can barely get my amp above -30db before I get complaints from the wife; and sometimes I have to put the subtitles up on the screen to follow all the dialogue.

Do you think I will be able to manage much of an improvement in volume level, if I put some insulation in ?


Ted White

Established Member
There are 4 elements of soundproofing. 4 things you can bring to bear.


Insulation perfroms the absorption role. While a good and necessary thing, absorption contributes the least, relative to the other three. People unfortunately often place a great deal of hope on the return on the insulation investment

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