In Japan, the owners can make decisions of design changes and pending issues for various reasons in phase of construction. Although those changes are mostly requested by owner, all additional cost or some can not always be allowed in negotiation between owners and general contractors. On the other hand, in U.S., the method is based on the contract so that the contractors can negotiate with owners about the additional cost for design changes.
This paper focuses on design changes and additional cost approval, to clarify the differences between Japan and U.S. on the construction contract agreement and their processes.
The paper shows conclusions as follows;
1. With this Japan-US comparison, the differences of the construction contract agreement are clarified in the articles for design changes, additional costs, claims, and allowances (Table 1).
2. Japan-US Comparison research of owner or contractor initiated design changes and additional costs processes in 4 projects (2 projects in Japan, and 2 project in the United States) revealed that; (Fig. 1-6 and Table 2)
a. In Japan, the responsibilities who take risk on design changes and additional costs are not clear and the decision making of the payment of additional costs are relied on the negotiation between owners and contractors for each project.
b. In the United States, the responsibilities are related to the owner when the design changes are requested by the owner or if it comes from design errors, omissions, and inconsistencies. Accordingly the payment belongs to the owner’s contingency.
c. In the United States, owners can settle allowances for pending issues in design phase. It can be adjusted by Change orders with depending on the actual construction cost.
d. In the United States, if owners do not pay the additional costs for design changes, contractors can negotiate with owners by claim clause in the construction contract agreement.
3. With this Japan-US comparative research of the system of design change and additional cost approval, it revealed some problems on Japanese process system as follows;
· The responsibility and risk for the additional cost is not clear between the owner and the contractor on design changes.
· Provisional specifications are not clarified on the contract documents.
