Core terms · definition
The structural sheet material (plywood or OSB) fastened over floor joists that everything else — underlayment and finish flooring — is built on. Squeaks and unevenness usually start here.
Source: InterNACHI — Inspection Glossary: Subfloor
Related terms
Where this term fits in a remodel
The pillar guides set terms like this one in context — what the work involves, what drives its cost, and where it sits in the sequence of a project. Pricing a specific house takes a defined scope and an on-site assessment.