acoustic mineral wool

[sm_jamieson]

OK, I put loft-style glass fibre insulation compressed to half its natural thickness in my new stud partitions (they are near doorways anyway, acoustic wool not required for building regs, but stops the hollow sound. However, I want to put in some proper acoustic stuff inside the boxing around the PVC soil pipe to minimise the flushing sounds. It seems the decent stuff is at least 45kg/m^3 and best stuff up to 60kg/m^3. Probably will be delivered due to the weight. Where is the best place to get this stuff (I am in the Midlands) ? Simon.

[Tim Lamb]

In message , sm_jamieson writes

Is expanding foam not suitable?

regards

[The Natural Philosopher]

No. acoustic deadening needs MASS.

mass and compliance are what you want. Sand is of course excellent.

[Tabby]

[therustyone]

IMHO wool is of very little benefit. The main thing is to use heavyweight material like 20 mm of MDF or chipboard to box it in all the way round, made airtight at the joints, and also insulate any clamps on the pipe itself to stop acoustic transmission to the exterior.

rusty

[Tim Lamb]

Undoubtedly. However mechanical connection through brackets or direct contact should also be avoided.

My very limited experience of doing this concerned an existing boxed soil pipe which was conducting *pongs* from some discharge point to a flat conversion. The cure was to inject some fire resistant foam which also happened to reduce noise.

regards

[Andy Dingley]

You need some mass in there. Layers of high-mass material, flexibly mounted, with layers of wool between them. Chipboard is one of the cheapest, Cement board is best, MDF isn't bad. If the location fits, hanging boards on wire from above is a good way to install it.

[Dave Plowman (News)]

Plasterboard is pretty good as regards density/cost.

[tony sayer]

Yes and no .. you some times need something light weight and absorbent to improve the room acoustics which can improve the sound isolation such as Rockwool or Earthwool..

Just been putting a load in a studio the other day....

[Dave Plowman (News)]

That's modifying the acoustic. A barrier to prevent sound transmission generally needs mass. Of course if you're using a double skinned one, some form of treatment between the two may reduce resonances.

[robert]

If you have access to the soil pipe then a purpose made acoustic pipe/duct insulation works exceedingly well - when I used it a few years ago I used a sheet material which I cut in strips to wrap round the soil pipe, fix with cable ties and duct tape. However I think you can get it preformed to standard sizes now. Not a cheap option, but doesnt take much space up and very effective.

[Andy Champ]

Pongs as in pings, not smells I take it?

Andy

[Tim Lamb]

Long sold on now so probably no comeback. PONGS!

The ground rent holder occupied the basement and ground floor with two flats above on long leases.

All sorts of structural problems as supporting stud walls had been removed to create *open plan areas*. The flat kitchen waste went through and round two bedrooms before reaching the soil vent pipe. Discharging hot washing up water resulted in a very drainsy effluvia in a bedroom. Re-fixing the waste pipe (avoiding sagging bits), fitting an air admittance valve did not solve the problem. Appeals to have the drains inspected fell on deaf ears so I emptied a can of fire resistant expanding foam into the boxing. Problem solved. A side benefit was quietening bog flushing from the flat above.

regards

[sm_jamieson]

Any details about this product and suppliers ? Simon.

[David Paste]

In this context, what does compliance mean?

[The Natural Philosopher]

The opposite of rigidity.

[tony sayer]

In article , Dave Plowman (News) scribeth thus

Yes quite but was just to point out theres differing aspects to noise reduction;!...

[David Paste]

Thanks. Would large rubber blocks be any good for sound deadening then?

[Dave Plowman (News)]

Yes - but most want wideband noise reduction. A mineral wool might help at highish frequencies, but not all. Adding mass should be good for everything.

[The Natural Philosopher]

That's true.

1. Remove all air paths. Tht cuts down air transmission
2. use materials whose structure causes multiple reflections to bounce sound around a LOT and
3. whose mass and compliance can absorb it as it does. Hard britlle 'ringy' materials are the worst. If someone made lead or depleted uranium sponge as a cellular foam, that would probably be best.Sand is good.
4. Watch out for the structure itself transmitting noise. The equivalent of a 'cold bridge'.