CSI Divisions 03 through 06 cover the core structural and enclosure materials found in nearly every building project. Division 03 addresses concrete, from cast-in-place to precast. Division 04 covers masonry, including unit masonry, stone, and associated accessories like reinforcement, flashing, and sealants. Division 05 handles metals, ranging from structural steel framing to miscellaneous metals like handrails and gratings. Division 06 covers wood, plastics, and composites, encompassing rough carpentry, finish carpentry, and engineered wood products.

For the PDD exam, you need to understand how to determine which specification sections apply to a given project, how to organize specification content using the three-part SectionFormat (General, Products, Execution), and what material-specific requirements govern each division. That means knowing the relevant ASTM testing standards for concrete and masonry, understanding quality assurance inspection levels, and recognizing how material properties like thermal expansion and moisture movement drive specification provisions.

These four divisions represent a huge percentage of what gets built. Getting the specifications right prevents ambiguity during bidding, reduces change orders, and protects the architect from liability when materials don't perform as expected. Knowing how to correctly specify expansion joints in brick versus control joints in CMU, or how to call out the right structural steel connection requirements, separates competent documentation from documents that invite problems.