In JCT 98, Condition 25.3.6:-
No decision of the architect under 25.3.2 or 25.3.3.2 shall fix a completion date earlier than the date for completion stated in the appendix.
However, where an architect has granted an extension, in considering a further extension he can take into account omissions issued since granting the first extension.
25.3.1 – the architect shall in fixing a new completion date state the extent, if any, to which he has had regard to any instructions under 13.2 requiring… the omission of any work.
