TL;DR
Installation shims are the tapered wood or composite wedges slipped between a window or door frame and the rough opening to hold the unit plumb, level, and square while fasteners go in, transferring loads at hinge points, lock strikes, and sill bearing locations. Paired and opposed, they form flat bearing stacks rather than point pressure that bows jambs and binds sashes.
What it means
Installation shims are the tapered wood or composite wedges slipped between a window or door frame and the rough opening to hold the unit plumb, level, and square while fasteners go in, transferring loads at hinge points, lock strikes, and sill bearing locations. Paired and opposed, they form flat bearing stacks rather than point pressure that bows jambs and binds sashes. Composite types resist the crushing and rot that wood ones suffer in damp sills, and excess length gets scored and snapped flush before insulation and trim.
Where it sits in the glossary
Installation shims 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
License: CC-BY-4.0 — quote freely with attribution to ProFix Editorial Team / ProFix Directory.