In construction, when delays are caused without contractor fault I found utilize 52.249-10 Default (Fixed-Price Construction) as it reads:
The Contractor, within 10 days from the beginning of any delay (unless extended by the Contracting Officer), notifies the Contracting Officer in writing of the causes of delay. The Contracting Officer shall ascertain the facts and the extent of delay. If, in the judgment of the Contracting Officer, the findings of fact warrant such action, the time for completing the work shall be extended.
However, in non-commercial services the clause is instead 52.249-8. I see this clause used for extensions to A&E contracts, but there is no similar language in this clause that stands out to me as an authority to modify the contract.
The closest thing would be 52.249-8(c) but it feels like quite a stretch.
What are your thoughts and how do you justify this on your authority matrix?