Particularly in claim disputes concerning delay in construction time caused by the client based on the VOB/B there is no consistent opinion concerning the consideration of the appropriate amount of general costs in the claims; mainly because this issue is quite complex with legal, cost theoretical and construction business management characteristics to be considered. After explaining the essential construction business management characteristics as well as the main legal and construction management principles in [1, 2], in this paper two new methods of estimating general costs in claim requests will be presented - the manufacturing costs/construction time method and the capacity utilization method. In a successive second paper both new methods will be validated and compared with two main, already in the practice existing methods concerning the cost evaluation of general costs. As result and in contradiction to the current practice general costs should not be considered in claims without additional construction time entitlement according to 2 clause 5 and 6 VOB/B. In contrast, additional construction time entitlement according to 6 clause 6 VOB/B should lead further to general costs, which depend on the relation of the additional contractual construction time to the original construction time under consideration of a correction factor.