Noggins

[jashton]

What purpose do they serve? I'm talking about the type found between Victorian ceiling joists. ie two battons that form an X.
I'm researching soundproofing for a bedroom ceiling and the recommendation is that noggins should be removed as they add to sound transmission. I'm not keen though in case they have some structural purpose. Can't see how. Are they used with lath/plaster to help prevent movement and subsequent cracking?

 

[masona]

To stop the ceiling joists twisting and make it more rigid

 

[jashton]

any thoughts on removing them?

 

[FredFlintstone]

To stop the ceiling joists twisting and make it more rigid

Most likely - could also be used to support a ceiling fixture in the room below such as a light fitting although generally such support is unnecessary.

 

[masona]

Yes that as well but I think the OP said X noggins which is known as herringbone noggins, normally made out of 2"x2" timber

 

[masona]

any thoughts on removing them?

Not really, maybe put in another lower ceiling below it

 

[Nige F]

What purpose do they serve? I'm talking about the type found between Victorian ceiling joists. ie two battons that form an X.
I'm researching soundproofing for a bedroom ceiling and the recommendation is that noggins should be removed as they add to sound transmission. I'm not keen though in case they have some structural purpose. Can't see how. Are they used with lath/plaster to help prevent movement and subsequent cracking?

.........you`ll get plenty of cracks on lath/plaster if you try and pull them out maybe the whole ceiling will let go ...........bad advice in the first place ........acoustics engineer in a pub?

 

[jashton]

not quite. This is in reference to installing a new ceiling, decoupled with resilient bar. The advice is is to remove the noggins before fitting the DFM. It's possibly because the fixing of resilient bar at 400mm centres will stop the joists from twisting so no longer any need for the noggins

 

[^woody^]

The noggins (or struts) not only stop the joists twisting (as humidity levels change), but they also form a structural function of binding the floor 'as one' so that individual joists don't bounce.

Fixing joists [horizontally] at the top and botton i.e. just by the floorboards and plaster ceiling, is not god enough except for small spans - less than 2m really. This type fixing alone can allow lateral (sideways), rotational (twisting) and vertical movement of the joists, which can lead to cracking of ceilings and dips in flooring

That is really bad advice to remove noggins, unless whatever is replacing them performs both of the functions of the noggins or struts

 

[Deluks]

Removing them will do nothing to reduce sound transmission, they only connect joist to joist, which are already connected via ceiling or floorboards, so you will still get transmission from joist to joist regardless.
Unless you require sound studio type soundproofing (then in special circumstances you could maybe remove one set if the joists in question are parallel on each side of a seperating wall), then it's completely pointless.
What exactly are you trying to achieve? or is this purely research for 'homework'

 

[jashton]

just research. I'm not going to remove the herringbone, just curious as to why the advice was to do so.

Woody - There would be resilient bar fitted perpendicular to joists, at 400mm spacing. I'm sure they would substitute the noggins.

I think the logic with removing the noggins is that the floor would be able to flex more independently and therefore not act as a massive sub-woofer. though as Deluks points out the ceiling will remain linked by the floorboards above so any benefit is going to be minimal. Main benefit will be from DFM and decoupling the ceiling completely using resilient bar.

 

[masona]

I'm researching soundproofing for a bedroom ceiling and the recommendation is that noggins should be removed as they add to sound transmission.

Can you show us the link for better understanding?

 

[jashton]

wish I could find the page that said remove noggins first but this is basically what I'm looking to install

http://www.soundservice.co.uk/Resilient Bar Fitting Instructions.htm

I'll be taking down the ceiling, installing 100kg DFM and then resilient bar, 19mm sound stop boards and final layer of 12.5mm PB

 

[^woody^]

From that image on their site, it is clear that the 'resilient bar' will not perform the same function as a noggin or strut.

It is only fixed to the bottom of the joist, and there is nothing to stop the joist twisting.

I would repeat, that it is bad advice to remove noggins.

Ask the company for a written, insurance backed warranty to cover the removal of any noggins, in that they will pay out for any movement of the floor as a result of their advice.

In addition, what you are proposing is structural alteration of the floor (fire and structure), and as such should require building control approval

 

[Deluks]

wish I could find the page that said remove noggins first but this is basically what I'm looking to install

http://www.soundservice.co.uk/Resilient Bar Fitting Instructions.htm

I'll be taking down the ceiling, installing 100kg DFM and then resilient bar, 19mm sound stop boards and final layer of 12.5mm PB

Whats this dfm stuff? Also 19mm sound stop might be a tad expensive, consider 12.5mm and 2 layers of 9.5mm, might work out cheaper and the soundproofing difference will be negligible (maybe even slightly better at certain frequencies)

I can't believe they are actually selling this, it used to be free info on their site, and all it does is recommend their own products. The screw prices on their site are unbelievable, they are probably normal drywall screws, which are all you need for this application.