The Contractor issued a delay notice which included numerous possible delay events and the CA did not request any further details of the events until about 16 weeks after the delay notice had been issued. Within 2 weeks of the CA’s request, the Contractor provided further information. The position which is unclear is whether the 12 week period began when the contractor’s further information was provided following the CA’s requests and what the implication is that the CA did not request any information within 12 weeks of receiving the delay notice.
If the delay notice is properly given under clause 2.24 then that is the date from which the 12 weeks runs. However, the general argument often followed is that the original notice was defective as it did not contain the information which was later requested so it is only once that information is provided that the 12 weeks can start to run.
Under the JCT (unlike FIDIC perhaps) the basic requirements of the notice of delay or relatively simple and therefore the 12 weeks will almost always start to run on that date.
There remains the question of the consequence of not answering in 12 weeks as there is no default acceptance or loss so a failure to notify under 2.25.2 rarely goes anywhere.