ORC 25 April 1989 Main contractors (B) were engaged by a housing association (CBF) to carry out extension works on a house. B did not complete by the original completion date and gave notice of delay . On the 5 March 1986 the architect awarded an extension of time , but B did not complete by the new date of 25 March and the architect issued a JCT 1980 clause 24.1 notice. CBF wrote to B informing him of their intention to deduct liquidated damages . In June the architect granted B two further extensions of time so that completion date became 21 April. B achieved practical completion on 18 July 1986. More than a year later, the architect granted yet another extension so that completion date became 20 May 1986. The final certificate was issued on 25 February 1988. CBF paid the agreed final account, less £4,900 claimed as liquidated damages for the period 20 May to 18 July 1986. In November 1988 the architect purported to give a new certificate that there was a failure to complete the wo