This paper presents a generic multilevel data model to support planning decision makers in the evaluation of production capacities and delays. The approach promotes rough but rapidly assessed views of the manufacturing capacities and of the production margins to provide planning decision with more reactivity. We first address the aggregation of planning-related technical data on products, processes and workshop capacity. Data aggregation is seen as a recursive process the depth of which is case-dependent. The aggregate data are then exploited for the assessment of the production makespan. The applicability of our generic approach is shown on a case study stemming from the wood transformation sector.