I have a steel door specification with interior door core construction type A, D or F and exterior door core construction type B, C, E or F. Can you tell me what these door cores are?
The references cited are from an outdated SDI 100 specification. The new specification, SDI 100 ANSI A250.8, does not contain letter designations for core material. The updated document provides a performance-based standard, such that an architect can be assured the doors will perform to the performance levels outlined in SDI 100 A250.8, regardless of core material. If an architect specifies a particular core material they will be limiting the number of manufacturers that supply that product, and perhaps the variety and styles of doors available to them. That is why it is better to base your choice on performance characteristics.