A workflow specification is a formal description of business processes in the real world. Its correctness is critical to the workflow execution and hence the realisation of business objectives. In addition to structural and temporal constraints, resource constraints are also implied in workflow specifications. Therefore, they should be analysed to ensure that the workflow specification is resource consistent at build-time. In this paper, we first identify the problem of resource constraints in a workflow specification. Then we propose an innovative approach with corresponding algorithms to the checking of resource consistency for a workflow specification. Furthermore, we extend our analysis work to timed workflow specifications, where time information is taken into consideration for the checking of the resource consistency of a workflow specification. The work reported in this paper provides a theoretical foundation for workflow modeling and analysis in workflow management.