Clause 34.3 is the claim. The standard form gives 28 days to make it in writing, counted from when you should reasonably have known of the delay.
How it flows
Check the clause in your own contract. Many owners amend clause 34, and some change the 28 days to a count of business days. The 1997 and 2025 editions use the same clause numbers for notice and claim.
Keep the notice short. Name the event, the date it started, the work it holds up and the clause. Send it to the superintendent by the method the contract names, and keep proof of sending.
A late claim can cost you the days and leave you open to liquidated damages. Diary the 28 days the moment you send the notice.
Under AS 4000, the extension of time notice is the notice of delay in clause 34.2. Give it in writing as soon as a delay looks likely. The claim for more time comes after, under clause 34.3.
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