TL;DR
A thermal bypass is an air pathway that lets conditioned air or attic air flow around insulation instead of through the intended building envelope, robbing performance even where R-value looks adequate on paper. Classic examples are open wall cavities under attic kneewalls, dropped soffits over kitchens, unsealed chases around flues, and gaps behind tubs on exterior walls.
What it means
A thermal bypass is an air pathway that lets conditioned air or attic air flow around insulation instead of through the intended building envelope, robbing performance even where R-value looks adequate on paper. Classic examples are open wall cavities under attic kneewalls, dropped soffits over kitchens, unsealed chases around flues, and gaps behind tubs on exterior walls. Energy auditors find them with blower doors and infrared cameras, and sealing them often beats adding insulation depth dollar for dollar.
Where it sits in the glossary
Thermal bypass 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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