Contractually, the previous responses are correct. The contract is lump sum, and the consultant’s underestimation is his own trouble to bear.

Strategically, as the client rep you’re going to want to consider how MUCH the consultant has underfunded himself and the affect that could have on your project. A consultant that cannot perform the services that you would like represents a risk that deserves acknowledgement.

Now that the consultant is aware of the underfunding, to what extent will they accept the loss of profit and increase manpower? To what extent are they willing to provide a substandard product in order to preserve their profit? Are you going to be struggling throughout the lifetime of the project with a consultant that consistently understaffs and subsequently underperforms?

Its most likely the best idea to force the consultant to increase manpower with no change to contract amount, but you should maintain a wider perspective on the implications that will have.

Norzul,

Assuming no increase in the original scope of work then under a lump sum agreement the starting position in English law is it is up to your consultant to produce the goods as required, end of story, no more money.

If he requires 100%, 200%, 300%, etc increase from his originally estimated manpower to forfill his obligations then I’m afraid that’s what he’s got to do and he doesn’t get anymore money for it.

Remember also, under a lump sum agreement it is up to your consultant (and any other party, contractor, etc) to complete his contract and that includes doing everthing you could reasonably have foressen at tender he would have to do and include, whether mentioned on the drawings, in the spec, in the contract, etc, OR NOT.

If there has been unforeseeable changes rom tender then it’s a different story but otherwise the above applies. Also check his contract to see there’s no get around clauses that apply.