Semidetached - can hear steps on f/boards - soundproofing?

[snowmaan]

Moving in this week, but in final pre settlement inspection, could hear shoes up and down the corridor next door from the neighbors!!

The agent said:

- The wall is not the problem, it's the flooring underneath - maybe the flooring isn't separated between the two semis?
- Also could be noise coming through from the roof cavity
- He said you can get a builder to come in and fix it for a few grand

If this is the case, I am thinking of approaching the new-to-be neighbors, with the suggestion we split the cost

Aghh, not at all impressed.
Apparently we probably won't hear voices or regular noise, but floorboard shoes we will.

Any thoughts???

 

[0000]

I investigated proper sound proofing once. Believe me it is not trivial, you basically need a room with in room the wall have studs alternating sides so the insulation is continuous, and this in addition to breeze block walls on the outside, and you can't have any interfacing (such as floor to wall) without isolation in between everything is suspended. Special grade insulation. special double/triple seals round the doors. You won't be able to breathe so, you need very complex soundproofed ventilation.

Windows forget it. It is a total myth that normal double glazing reduces noise, in some case it can actually make it worse. Recording studio windows, have panes of different thicknesses (but can be very thick specially made glass), you need at least four inches in-between the glass where one of the panes is slightly tilted. the are are insulated from each other which is consistent thought the whole wall.

What people call sound proofing isn't really. It is just muffling so you brain register it less. It is more the general noise around you all the time that is making you filter stuff out. Waveforms combine partly cancel in places.

You won't be able to do anything about is the interfacing, but you can fill space with insulation material. It is not about filling the whole gap. The air gap is quite important.

 

[Deluks]

On the right lines Agent 0000, but you describe overly elaborate solutions for a simple party wall
(oh and you're slightly wrong about the insulation/air thing )

OP: Without knowing the construction of the property you won't get much advice. We don't know whether your gaff is made from brick, timber, concrete or swiss cheese.

 

[0000]

sorry I should have been clearer in-between should completely filled end to end, but parallel within the cavity you can have an air gap. There isn't an added advantage to touching both sides.

 

[Deluks]

Your error is..................

The insulation does the same job as the air. Only better

Full filling is advantageous. Assuming we're talking bout the same inso, rockwool all the way!

Of course using a rigid foam insulation would be less desirable for full fill, so if you were referring to a kingspan tech sheet then you are correct. But that would be the wrong choice of material in the first place, for soundproofing purposes

 

[0000]

you are right but your logic is wrong

Rock wool block out a lot, 'rigid' fibre glass performs better still. However blocking out multiple frequencies is not a single material job. You have absorption and diffusion. Geometry is also important for diffusing.

http://www.ethanwiner.com/acoustics.html

"One important way to improve the low frequency performance of any absorbent material - besides making it thicker - is to space it away from the wall or ceiling. For a given material thickness, increasing the depth of the air gap lowers the frequency range it absorbs. For example, 703 that is two inches thick and mounted directly against a wall has an absorption coefficient of 0.17 at 125 Hz. Spacing the same material 16 inches away from the wall increases that to 0.40 - a nearly three-fold improvement."

 

[JohnD]

grrrr, maybe they've put down laminate flooring

a nice thick carpet and felt underlay are a lot more neighbourly.

buy yourself some hobnailed boots and run about a bit before you talk to them about sound reduction, or they might think it's just you being oversensitive.

 

[0000]

My sister has an old town house, which is split into flats. The floorboard are real old warped and have worm holes in. The creaks and cracks from the flat above are creepy.

 

[Deluks]

you are right but your logic is wrong

Rock wool block out a lot, 'rigid' fibre glass performs better still. However blocking out multiple frequencies is not a single material job. You have absorption and diffusion. Geometry is also important for diffusing.

You've gone a bit off track here though, your links and quote are relevant to acoustic treatment inside the room. Completely different kettle of eggs to the actual blocking of sound between properties.

If you had 16" of space to play with, and completely filled the void, it would provide more resistance to sound than having your 2" of insulation occupying the same space.

 

[0000]

There isn't much this guy can do if is the interface not the wall cavity that its the problem. if there is something that transfers the sound well that can't be removed, putting insulation beside it won't help.

 

[ajrobb]

I didn't see which way the joists run. Insulating walls might not help with impact noise if it is coming through the joists into the floor above and the ceiling below.

 

[mointainwalker]

@ 0000

Can you please explain the quote below ?

Rock wool block out a lot, 'rigid' fibre glass performs better still

The rigid material is the same as the roll material but with a stiffener to make it stand up when used as thermal insulation i.e. it is not compressed. Why do you think there is a difference when it comes to sound insulation ?

 

[Deluks]

@ 0000

Can you please explain the quote below ?

Rock wool block out a lot, 'rigid' fibre glass performs better still

The rigid material is the same as the roll material but with a stiffener to make it stand up when used as thermal insulation i.e. it is not compressed. Why do you think there is a difference when it comes to sound insulation ?

He was talking more about acoustic treatments. Which is all dependent on which frequency you are trying to 'treat' not really relevant.
That said, different materials will perform differently for sound insulation, denser is better, so slab insulation will have a slight edge over roll which tends to be slightly more 'transparent'