NHBC standards for chipboard floors on I-joists?

[Kate123]

We are having the same issue in our 6 month old house, initially this work was done to one room which hasn't stopped the cracking noise from below:

Removed old flooring which had been glued and nailed to timber joists. Joists are at 400mm centres and have staggered noggins nailed in the centre of the span from wall to steel RSJ. Joist length is approx 4.1m
Re screwed noggins as a precaution with 100mm x 5’s.
New boards down and glued with egger D4 glue as per manufacturer instructions, the boards are also fixed with 75mm screws on every joist, 3 per joist.
Glued and screwed a noggin to the perimeter as needed.
Where the boards cross the steel used gripfill green so the boards are not directly on the steel.

The warranty holder Homeproof (was Aedis) have now backtracked and said the Developer doesn't have to do any remedial work as it not covered as 'Major Damage' in their policy so they and the Developer are not liable.

So if we have to do the work ourselves has anyone tried the NHBC fix as per the joint statement? How much does it cost per room and how long does it take in terms of disruption etc and had it worked? How do we find someone who knows what they are doing as well?

I know I am preaching to the converted about the scandal of the lack of protection for owners of new builds.

[New Home Expert]

Everything that a buyer reports to the housebuilder that is not fully remediated before the expiry of two years after legal completion, is still the builder's responsibility to deal with. If not the NHBC should take over.

Fitting plywood gussets to the side of the I joists would invalidate the Joist manufacturer's warranty, unless their engineers have designed it.  You do not need to be a structural engineer to assess whether a bouncing (deflecting) floor is excessive and/or the cause of other reported defects.  It beggars the question as to why housebuilders (often backed by warranty providers) still proceed with fitting resilient bar when this will not prevent deflection at all and is probably not much additional work to fit additional and strange joists at that time when the ceiling is down.

Yet they seem to prefer to "bodge" hoping the occupier of the home will not want any further mess and inconvenience!