NEC ECC: Temporary propping of bracing - is this a Defect?

I have a Consultant PM employed under the NEC3 PSC. My Consultant PM is managing the construction of a new building and I oversee his part in that process. The main Contract is an NEC3 ECC option B Contract. Prior to the steel frame going up, the Contractor submitted their methodology for erection of the steel, as per the Works Information, for designer’s acceptance. This was reviewed by the Design team and the proposal was accepted. Despite the methodology having been accepted, and before starting work, the Contractor questioned the temporary stability of the frame and made a decision to order additional steel bracing prior to the proposal being put to the Consultant PM, giving him opportunity to accept the proposal (or not).

Upon receipt of the CEN for the steel the PM consulted the design team who insisted that the additional bracing was not required and the design team backed their statement with additional calculations to prove this. As a result the consultant PM rejected the CEN. The Contractors response was that the frame was not safe to erect as per the design information and went ahead and used the additional steel anyway. Note that the Contractor is responsible for all temporary works (CDP in the contract).

At the time it was stated by the Contractor that the additional steel would be temporary and be removed later and therefore a Defect Notice was not issued. However, the Contractor has now decided that it would take too long and impact the programme to remove it and wishes to leave it in. None of the above has been accepted by the PM through any Contractor proposal. The Contractor has now raised an RFI requesting that the designs be amended because they realise that the blockwork wont fit around the additional steel and windows etc cannot be installed as per the Works Information. In order to address the initial dispute, we as the Employer, have arranged for an independent review to be undertaken of the design of the frame however, this is going to take a little while to complete and the Contactor is pressing on.

Question: Who is now responsible for updating the design, bearing in mind no PM acceptance exists for any of the above permanent works and the Contractor is only responsible for temporary works under the CDP? What are the Contractual ramifications for this problem?

As always the devil will be in the detail. On face value if the temporary works are not stipulated in the Works Information then they are a matter for the Contractor to deal with.
The PM’s acceptance of the methodology does not relieve the Contractor of their obligations, one of the principal ones being to provide the works in accordance with the Works Information.
If the PM is not prepared to accept the temporary works remain in place then the matter is a Defect and a Defect Notice should be issued. It seems the solution is for the Contractor to remove the temporary works but I would suggest an early warning/risk reduction meeting be held to review the options.