On the surface, the JCT 2005 extensions of time clauses appear unchanged, but a closer look at the new wording suggests they could prove quite tricky

I held a workshop for contractors recently during which I asked them which of the clauses in JCT2005 they wanted me to talk about. The immediate response was "extensions of time". So how has that clause changed? Well, first of all the name has changed and we should now refer to "adjustment of completion date". This is technically more accurate.

The "adjustment" clauses in the intermediate and minor works forms are largely unchanged, except for the relevant events in the intermediate building contract. There are some changes in the standard and design-and-build versions, though. First, the relevant events. Some old faithfuls have gone - late instructions, works instructed by the employer direct, materials supplied by the employer, changes in access to the site and compliance or non-compliance with health and safety clause 6A.1. These are all matters of employer's risk and it is intended that the sweep up clause - "any impediment, prevention or default … by the employer or any of the employer's persons" should be used instead.

There is one further omission, clause 25.4.10 in JCT1998 - the unavailability of labour or materials. This clause was almost always deleted, so the omission may not make much difference. There were circumstances, though, most recently during the steel shortage, where it could still be appropriate. The clause related only to the unavailability of labour or materials that the contractor could not have foreseen at the base date. It was not a question of awarding the contractor an extension of time for its inefficiencies in organising the works but rather to deal with some unexpected problem, such as the collapse of an overseas supplier.

There are more subtle changes in the wording, and parts of the clause are really a lawyer's playground. JCT has kept the wording largely unchanged but sometimes it has made minor changes and the question is, do these make a difference? For instance, the contractor is to give notice of a relevant event and estimate "the expected delay in the completion of the works". The 1998 wording went on to say, "whether or not concurrently with delay resulting from any other relevant event". By leaving out the reference to concurrency, does the contractor no longer need to give a notice of delay if it believes it is concurrent with other delay? Language is a fascinating thing; although that wording has been left out, the contractor's obligation is still to provide an estimate of the delay in relation to any relevant event, regardless of whether they are concurrent with other events. Taking the words out should not make any difference to the obligation.

There is a more significant change in wording in relation to the "particulars" that the contractor is to provide, setting out the effects of the delay. Previously the architect or employer (depending on which form was being used) did not need to respond by fixing a new completion date if the particulars were not "sufficient". That wording has now been omitted, which seems to mean that the architect, contract administrator or employer must fix a later date even on insufficient information. It is still in a contractor's interest to give detailed information, however. The architect, contract administrator or employer only needs to fix a later date which it estimates to be fair and reasonable, and that will be based on the information received.

There is also a reference to the architect, contract administrator or employer providing its decision in 12 weeks of receiving the "required particulars". Does this mean whatever particulars the contractor has managed to put together, or particulars that are sufficient for the architect, contract administrator or employer to make a proper decision?

Another change in the wording is that where there are fewer than 12 weeks between the particulars being received and the completion date, the architect, contract administrator or employer need only "endeavour" to provide its decision on extensions prior to the completion date. Previously the obligation was to make a decision "if reasonably practicable", which is a heavier obligation.

So although the wording looks rather familiar, it is not safe to assume that the effect of the new JCT2005 wording is the same as JCT1998.