TL;DR
Z-flashing is metal flashing bent into a Z-shaped profile and installed at horizontal joints in siding and trim, over the top edge of panel siding seams, band boards, ledger trim, and window head casings, so water stepping down the wall is carried out over the face of the material below. One leg tucks up behind the upper material and weather barrier, the horizontal web caps the joint, and the outer drip leg sheds the water clear.
What it means
Z-flashing is metal flashing bent into a Z-shaped profile and installed at horizontal joints in siding and trim, over the top edge of panel siding seams, band boards, ledger trim, and window head casings, so water stepping down the wall is carried out over the face of the material below. One leg tucks up behind the upper material and weather barrier, the horizontal web caps the joint, and the outer drip leg sheds the water clear. Horizontal joints in T1-11 and panel siding fail without it, swelling and delaminating along the seam, and caulk substituted in its place is a maintenance treadmill rather than a fix.
Where it sits in the glossary
Z-flashing is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
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