Definition
A Z-shaped metal flashing installed at horizontal joints in panel siding (like HardiePanel) to prevent water from entering the seam.
Related Terms
Aluminum Siding
Lightweight metal siding popular from the 1940s-1970s. Durable and low-maintenance but dents easily and can oxidize over time. Still found on many Colorado homes.
Back-Primed
Siding that has been primed (sealed) on the back side before installation. Back-priming prevents moisture absorption from behind, extending the life of the siding — especially important for wood and fiber cement.
Batten
A narrow vertical strip applied over joints between siding panels in a board-and-batten installation. Creates a distinctive vertical pattern.
Board and Batten
A siding style using wide vertical boards with narrow battens covering the seams. Popular for farmhouse, modern, and rustic architectural styles.
Butt Joint
Where two horizontal siding boards meet end-to-end. Butt joints must be caulked and staggered between courses to prevent water infiltration.
Caulk / Sealant
Flexible waterproofing material applied around flashing, penetrations, joints, seams, corners, and around windows and doors to prevent water and air infiltration. Must be compatible with materials and rated for exterior use. Must be regularly maintained and replaced as it ages.
Cement Board
See Fiber Cement Siding.
Channel
A J-shaped or U-shaped trim piece that receives the edge of siding panels. Used around windows, doors, and at transitions.
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