Door glossary

Prehung — a door already mounted in a complete new frame with hinges and usually the threshold. Slab — just the door panel, no frame or hinges. Which one your quote covers is the single biggest driver of price difference between bids.

Jamb — the vertical sides and head of the frame. Sill — the horizontal bottom member the door closes onto. Threshold — the piece you step over, often adjustable. Rough opening — the framed hole in the wall behind the trim, which is what a prehung unit has to fit into.

Handing — the combination of hinge side and swing direction. Conventions vary by supplier, so always also state it in words. Sidelight — a narrow fixed glass panel beside the door. Transom — a panel above it. Astragal — the vertical seal strip where two door panels meet on a double door.

Weatherstripping — the compressible seal around the frame; a wear item. Door sweep — the seal at the bottom edge. Sill pan — a waterproof tray under the door that catches and drains any water that gets past the seal; a key detail on exterior installs. Strike plate — the metal plate on the jamb the latch and deadbolt engage.

How to choose

Learn prehung vs. slab first

It explains most of the price variation between quotes and determines whether a damaged frame gets fixed.

Rough opening is not the door size

The rough opening is larger than the unit to allow for shimming. Don't quote one number when a supplier asks for the other.

Ask if a sill pan is included

It's a small item that determines whether water gets drained out or into your wall framing. Get it named in the contract.

Check strike-plate screw length

Long screws reaching the wall framing are a meaningful security detail that costs almost nothing.