The respondent Nieman Naas said

1. "the value of the extension of time should be the cost incurred by the contractor."

2. "This can be estimated by reviewing the time dependent costs included by the contractor in the preliminaries BoQ."

3. "As the consultant you have a duty to be fair and reasonable, and to take an unbiased view of the submissions by the contractor as to his entitlement."

4. "You know how many staff, transport, plant etc the contractor has on site, and you know how much they are likely to be paid, so you can take a view on entitlement."

Point 1 is correct where the prevention is caused by the employer, but, not if there is no fault i.e. inclement weather;

Point 2 the time dependant sums or rates included in the Preliminaries BoQ are to a large part an estimate themselves and as such do not necessarily reflect the cost to the Contractor. One has to look at the merits of each case and make a decision based on whatever facts can be established;

Point 3 adopt the prudent approach by examining each method and arrive at a position and make your decision impartially, (by the way there is no Contractor on this planet who is capable of 110% effort, 80% is pretty good for a reputable firm remember the Peto principle) therefore be reasonable and fair and stand by your decision it then is out of your hands and is dependant on the two parties to the contract striking their own deal;

Point 4 you need to consider all the variable costs. There are formulas that can be employed, but these are not without criticism (Hudson, Eichlaey and Emden);

You are right Faried Khan this is open to abuse and is probably dependant upon your own skills at management and negotiation (bluff and counter bluff). Do not confuse prolongation costs with the price for work to be executed. The price for the work still to be executed will be picked up in the lump or in the re-measure and any escalation costs would be dependant on some Consumer Price Index or some other formula to be agreed for escalation.

The Contractor will have to show evidence that there were 100 men on site which could probably be corroborated by examining the site diary and the Monthly progress report which you will have been reviewing and challenging as the project progressed as well as conducting your own spot checks which in my experience most consultant Project Managers carry out throughout the project. However, if the Contractor is claiming he needs 100 men to do a 10 man job then simply put it into labour manhours for the job and pick up any estimating book with labour constants in it and make your own judgement and show the Contractor how you have arrived at the result. Even if you were to give a little you would never arrive at 1000 times difference.

One of the things you have to remember is that once you get to the stage of Claims presentation, there is little scope for the Contractor to misrepresent the situation as they will no doubt be preparing for a protracted court battle. One of the things you cannot do is present a case that will loose credibility at the first sitting. The barrister/advocates are experts at sniffing out incredulity. In fact the Contractors Council will be playing devils advocate long before the case ever gets near to court.

There are many sources of information available that tell you what you can claim and what the normal heads of claim are. You can even find advice telling you that you can have acceleration costs at the same time as you are incurring disruption costs. In Sharia compliant countries no man can benefit from another mans misfortune, therefore, you can even claim certain bank charges that you just cannot name.

Good luck.