TL;DR
A floor joist is one of the repeated horizontal framing members — sawn lumber, I-joists, or open-web trusses — spanning between beams or foundation walls to carry the floor above, set at 12, 16, or 24 inches on center. Sizing comes from span tables balancing species, grade, spacing, and load; residential floors are designed for 40 psf live load with deflection limits that govern bounce.
What it means
A floor joist is one of the repeated horizontal framing members — sawn lumber, I-joists, or open-web trusses — spanning between beams or foundation walls to carry the floor above, set at 12, 16, or 24 inches on center. Sizing comes from span tables balancing species, grade, spacing, and load; residential floors are designed for 40 psf live load with deflection limits that govern bounce. In sheds, pressure-treated 2x6 or 2x8 joists over skids are typical, and joist condition is what an inspector probes when a floor feels springy.
Where it sits in the glossary
Floor joist 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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