TL;DR
The drainage plane is the continuous water-shedding layer hidden inside an exterior wall — housewrap, building felt, fluid-applied membrane, or taped sheathing — that intercepts water getting past the siding and directs it down and out at flashings. Every window, deck ledger, and penetration must lap into it shingle-style or the wall can rot invisibly.
What it means
The drainage plane is the continuous water-shedding layer hidden inside an exterior wall — housewrap, building felt, fluid-applied membrane, or taped sheathing — that intercepts water getting past the siding and directs it down and out at flashings. Every window, deck ledger, and penetration must lap into it shingle-style or the wall can rot invisibly. Inspectors check that flashing tape and weather-resistive barrier laps follow the manufacturer's sequence before siding goes on.
Where it sits in the glossary
Drainage plane 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.
ProFix tools that touch this term
See also
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