Answered: NEC3 ECC: Is the Contractor required to procure Professional Indemnity Insurance because he has design responsibility for temporary works?

In the first instance the costs of any insurance policy you provide is deemed included within the Fee and therefore (unless there is a specific contract amendment) then Employer does not have to pay it as a Defined Cost.

I open to be corrected here but it is my understanding that PII is provided by the Contractor to cover his liability for errors in his design of any elements of the permanent works (i.e. once they are constructed).  I have never come across a situation where PI is required by the Employer for temporary works (of course you may wish to independently procure insurance to cover design issues in your temporary works but that would be your choice).  I suggest that you check the wording of your Contractor's All Risks policy.  If a design error caused a failure in the temporary works that subsequently damaged any permanent works constructed to date then the insurance to cover your liability in the first entry of the Insurance Table in 84.2 (Loss or damage to the works, Plant and Materials) would, I suggest, cover you.  

Be careful though of your policy wording .  It may be worth checking with your brokers to determine what your CAR policy actually covers you for.