Soil stack sound insulation

[Dazza Jones]

I have a 3 storey house (might be relevant) with an internal soil stack that vents in the loft.
I am in the process of doing some work in my bathroom on the 3rd floor. The pipe is boxed in the corner of the bathroom, currently with 2x 15mm plasterboard covering it, but the pipe does not have any insulation or lagging wrapped around it.i was surprised by this as I thought the pipe was supposed to be lagged.


I then read this Nhbc info:

SOIL AND WASTE SYSTEMS
8.1 - S8

(c) sound insulation of pipes
Insulation should be provided to all soil pipes passing through dwellings.

This info replaced the word AND with the word OR in my understanding.

I would like to reduce the 2x 15mm plasterboard boxing to 1x 12.5mm plasterboard.

Am I correct in saying I can do this if I wrap the pipe in insulation, Rockwood or similar.

Many thanks.

 

[freddiemercurystwin]

Have you noticed any problem with any noises emanating from the pipe up to now?

 

[lt8480]

As you know there is no lagging I assume you have already stripped off the plasterboard. In which case I'd suggest insulate, then reline with plasterboard and see how it performs acoustically, and then make the decision whether to add another layer.

A heavy weight/acoustically design plasterboard will help avoid the need for a second layer.

As the boxing is in the bathroom you might conclude that acoustic performance here is less critical as you have just ran the tap/flushed the toilet so the sound is unlikely to be an annoyance (more important where a pipe running through another room).

If the bathroom was a lower floor and another bathroom's waste from above ran through the same stack you may also wish to insulate better.

 

[Tigercubrider]

a building that I worked in was three stories but with high ceilings- being commercial.
There was a gents on top and the soil ran through each floor internally, boxed in with ply or block board.

The sound of a flush, and the solids bouncing down the pipe turned your stomach. By the time it hit the ground floor it was really loud

 

[JP_]

shove insulation down there?

 

[Dazza Jones]

Thanks for the replys.

The side of the boxing that i have stripped out to discover there is no insulation forms one wall of my shower alcove, and whilst i can hear the noise of the water going down now that the plasterboard has been removed, it wasn't an issue before.

My concern was of breaking a 'code of practice' or building regulation when i build it back up.

It would be better for me to be able to lag it then one wall be of Aquapanel cement board.
If this wasnt to 100% comply, what would the ramifications be? If any?

 

[lt8480]

NHBC is not building regulation, the requirements you are looking at I suspect are the HNBC requirements for new homes. Also, if the pipe is only in one dwelling I don't believe there is a regulation for this - and the HNBC part you are looking at is for flats and where a pipe passes through another dwelling.

The building regulation is similarly worded - Part E - para 3.41 - 3.42:
"3.41 Pipes and ducts that penetrate a floor separating habitable rooms in different flats should be enclosed for their full height in each flat. See Diagram 3.6.
3.42 The enclosure should be constructed of material having a mass per unit area of at least 15kg/m2. Either line the enclosure of wrap the duct or pipe within the enclosure with 25mm unfaced mineral fibre"

If the soil pipe vents through the roof it might still want lagging for thermal reasons.

 

[Nige F]

a building that I worked in was three stories but with high ceilings- being commercial.
There was a gents on top and the soil ran through each floor internally, boxed in with ply or block board.

The sound of a flush, and the solids bouncing down the pipe turned your stomach. By the time it hit the ground floor it was really loud

That's because it was a turd at 32 feet per second per second. But if it had been an aeroplane on a conveyor belt................................