Sound deadening in modern property

[Seb101]

My house is terrible for sound proofing, both floors and walls. From the master bedroom you can hear people talking in the lounge as if they were in the room, and you can hear the trickle of the shower running in the bathroom - 2 entire rooms away! Not to mention when someone is playing the piano, even moderately (hard to adjust the volume on a real piano ) the neighbours start banging on the walls . The floors are also very 'boomy' as in you can hear people moving about even when they tread lightly.

I get the feeling my house was slung up in the cheapest possible fashion (or maybe this is just the modern way). There are no 'solid' walls, everything is plasterboard over metal rails - even the 'exterior' walls. The upper floors are actually quite thick - they are made of what I can only describe as wooden "I-beams" - two flat joists with a vertical chipboard section between them, about 50CM apart, with about a 30cm air gap between ceiling and floor.

I'm about to do some major work, moving some internal walls around, and replacing all the flooring, so I want to take the opportunity to put as much simple sound-deadening in as possible.

I assume the best way to achieve this is some sort of sound-deadening fireproof foam type material in the cavity?

Can you give me some suggestions for - firstly the walls (I've had a peak and there is about 7cm gap between plasterboard and blockwork). And secondly the floors - it's a big gap to fill.

Cheers!

 

[jeds]

You don't say how old the house is. Sounds like you're describing a house of about 20 or 25 years ago, which, I suppose, might be described as modern. Standards have improved over the last 10 years so if it's less than that it should be a lot better than you describe. The main differences are voids filled with acoustic mineral wool, (mineral - don't use foam) plasterboard will be thicker or denser - or both - and floor boards will be thicker and denser. So as you renovate and move walls definitely use heavier plasterboard and fill voids with acoustic mineral wool. If you take any ceilings down you could also consider replacing the boards on resilient bars.

PS. The beams you say can only be described as wooden "I beams" are (wait for it) wooden "I beams".

 

[theprinceofdarkness]

Just to underline, "voids" included the ceiling floor gap. My MILs 1970s build is like this, you can hear whats going on in the toilet from the kitchen, via the hall with the utility room in way. Heavier doors will help as well.
Frank

 

[tony1851]

Sound is like water; block one access point off and it will find another.
Modern houses being so lightly-built just lack the damping effect of weight, which is one good way to attenuate noise.
The fancy (and sometimes overly-complex) detailing provided today is no real substitute for mass.

 

[Seb101]

Sorry I did forget to mention - built 2003. So just before things got better by the sounds of it!

Yep - very thin plasterboard and VERY thin partition walls - about 10cms total thickness - you can actually bend the plasterboard inwards if you push in the right places.

Mineral wool sounds like the way forward then. Should I fill the floor voids completely - or just a layer on the ceiling? Can mains cables be run through the wool or do they need to be conduited?

What are these 'resilient bars'? I've seen it mentioned a lot in sound proofing forums.

Ta!

 

[mike42]

Sound is like water; block one access point off and it will find another.
Modern houses being so lightly-built just lack the damping effect of weight, which is one good way to attenuate noise.
The fancy (and sometimes overly-complex) detailing provided today is no real substitute for mass.

Caveat: I'm not an expert or builder. I just wanted to add, that we had/have a similar problem. In one bedroom, I removed one side of the partition wall, filled the gap with rockwool, and replaced the plasterboard on that side with a (I think it was 15mm) "accoustic" board. Its long been finished and look beautiful but unfortunately, all that work was virtually for nothing as it seemed to have made no difference. I totally agree with the quote above.

 

[Nige F]

S

Yep - very thin plasterboard and VERY thin partition walls - about 10cms total thickness - you can actually bend the plasterboard inwards if you push in the right places.


Ta!

Well I suppose one good thing in my 60's bungalow is it's 100mm ( 4 inch ) block walls (total finish ) the blocks are so thin it's a wonder the brickies got them straight and plumb. Er, they didn't but at least they are solid.

 

[jeds]

Sorry I did forget to mention - built 2003. So just before things got better by the sounds of it!

Yep - very thin plasterboard and VERY thin partition walls - about 10cms total thickness - you can actually bend the plasterboard inwards if you push in the right places.

Mineral wool sounds like the way forward then. Should I fill the floor voids completely - or just a layer on the ceiling? Can mains cables be run through the wool or do they need to be conduited?

What are these 'resilient bars'? I've seen it mentioned a lot in sound proofing forums.

Ta!

100mm mineral wool in the floor void. Try not to leave any gaps in the insulation. Cables can be clipped to joists as normal. The purpose of resilient bars is to minimise the physical connection between boards and joists/studs. The two together help stop the floor acting like a drum. You aren't going to make it perfect but if you have the opportunity to upgrade whilst doing work anyway then it is sensible to take advantage of the situation. Rule of thumb is that 90% of sound travels through 10% gaps. So seal anything you can; skirtings to floorboards, gaps between boards, etc. In a designed acoustic scheme you would double board ceilings with 15mm boards with staggered joints on resilient bars. I don't care what anybody says, a properly designed and built timber floor produces a MUCH quieter floor than any concrete rc or beam/block floor. I've designed both, which have been tested under Part E, and the heavy floors are always close where timber floors pass easily. Detailing is important though.

 

[JohnD]

I will just add that the mineral wool for sound deadening is dense wool batts, they are heavier and stiffer than the lightweight rolls used for loft insulation. Builders merchants usually have them in bales of individual slabs which are of convenient size to carry and fit.