CHAPTER 22 Contract Modifications

Up to this point, the majority of the text has viewed estimating from the bidding phase. However, estimating does not end once the project has been awarded and the work is under way.

On all projects, changes occur. Some changes have an impact to cost, and as a result those changes require estimating. While the actual mechanics of the estimating process for change orders is the same, there are different dynamics that the estimator must consider.

This chapter will introduce the tangible differences in the dynamics of estimating change orders.


As with all projects, things change. The individual reasons for the changes are numerous and varied. Changes can occur in project scope, contract amount, or contract time. It can be one, two, or a combination of all three. Changes to the contract are aptly termed contract modifications and can be the source of disagreements or even outright battles between parties. Contract modifications by definition are regulated by the contract in the exact same way that the base scope is governed by the contract. There are many misconceptions about contract modifications that are harbored by owners and architects, the most popular of which is that contractors make all their money on changes orders, after underbidding the project. For the majority of contractors, contract modifications are more of a headache than a revenue stream, especially the small ones. Contract modifications fall into two ...

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