Noggins or Herringbone under Replacement Floor

[DIYinBerks]

In process of replacing a first floor bedroom floor - primarily to increase sound insulation. Have discovered just one set of Noggins across 4m of span which seems a bit light and thought I might add another two. the floor - 7" x 2.5" joists - has always been a bit lively. Any advice of the best to use?
Noggins - would seem tricky since the joists are not that evenly spaced and some a bit twisted so I would need precision measurement on each one.
Metal Herringbone - can't see how this works at all in a replacement job since the tie needs fixing under as well as over the joist.
http://www.strongtie.co.uk/pdf/HSA.pdf
Wooden Herringbone - will this give noticeable additional rigidity? I was thinking of screwing them on to avoid the potential of damage to the existing ceiling.
...or should I bother at all?

 

[dann09]

Why not use solid blocking off-cuts of an appropriate section. eg. 6" x 2".

Definitely, pilot holes and pre-set screws. Use a power drill/driver.

google/research sound insulation - a very tricky business. If you've not yet lifted all the T&G flooring, then pause for research results.

 

[DIYinBerks]

Did some research and was not sure if I should even bother... but we needed a new carpet & I thought "now is the time" So I have gone ahead and lifted the old floor - which was 18mm chipboard - so hopefully don't say I am wasting my time? I am hoping that by gap filling between wall blocks and plasterboard (dot and dab, was open at the top); boxing in the downlights (generous size to allow cooling) laying some fibreglass between the joists; replacing with 22mm chipboard; using foam to gap fill round floor; and using a thicker carpet underlay -- I will get some improvement without actually spending a fortune. I needed to buy some boarding for the loft anyway, the old 18mm will go there so this job is not costing a lot. A proper acoustic ceiling/floor combination would have been a major change and major cost.
The question of the noggins or herringbone struts is a bit incidental, just wondered if I should do it while the floor is up.

 

[JohnD]

It seems to me that Ply is less noisy (as wel as being stromger and more durable) than chipboard

You can get denser grades of mineral wool as "batts" which are better for for sound absorbence than loft rolls.

 

[DIYinBerks]

I didn't find any evidence that plywood was quieter than chipboard - in fact the high performance acoustic flooring I saw on the web seems to be generally chipboard or MDF plus other layers.

Batts probably better I agree, much better for a given thickness - but also many times more expensive. I think my 175mm of general purpose fibreglass will give me similar performance to a 30mm acoustic batt - but at a fraction of the price.

 

[dann09]

Problem is, that much sound is transmitted thro any relevant materials, for instance, sound will travel along the joists and into the walls, and then transmit thro the wall in various directions.

Another difficulty is, that you tackle your sound issues, but what then about the neighbours?

Various attempts have been made by local authorities and BRE etc. to come up with better sound proofing detailing, but i think that most innovations fell by the way.
Typically, some kind of "Flash Band" type strips were installed under sole plates and joist tails, or even capping joist tails in the stuff. Also different types of insulation and spray-ons and foams.

Funny enough, on-site experience, FWIW, convinced me that laying P/B sheets across the joists before boarding out, like an underlayment, was a reasonable and cheap method, but far from perfect.

 

[DIYinBerks]

Sorry, what's P/B sheet?