Door jamb
A door jamb is the vertical side of a door frame that the leaf closes against, fixed plumb and flashed before cladding; out-of-plumb jambs are a common fit defect.
Ask Chalkline about this →A door jamb is the vertical side of a door (or window) frame that the leaf or sash hangs from or closes against. It is fixed plumb into the opening and flashed before the cladding closes the wall. Out-of-plumb jambs are one of the most common door and window fit defects.
A door frame has two jambs (the hinge jamb and the lock/strike jamb) and a head. The jambs do the work: the hinge jamb carries the door’s weight and must be dead plumb and rigid so the door swings true and does not drop, and the strike jamb has to be plumb and parallel so the door closes evenly and latches. They are packed and fixed to the studs at the hinge and strike points so the fixings do not pull the jamb out of line.
The waterproofing sequence matters as much as the fit. On an external opening the jamb has to be flashed (sill, jambs, head) and tied into the wall wrap or sarking before the cladding goes on, so water that gets behind the cladding is directed out, not into the frame and wall.
For a builder the practical points are to set the jambs plumb, straight and parallel, packing solidly behind the hinges and strike so the fixings do not bow the jamb, and to get the flashing in the right order before cladding. A jamb that is out of plumb or twisted gives a door that drops, binds, or will not latch, and a jamb flashed after the cladding is a guaranteed leak. Check the reveal and margins are even all round before you hang the leaf.
Also known as: Jamb, door frame side.
Category: Doors and windows / Carpentry.
Related
See also
References
- External doors (Chalkline) (verified 2026-06-01)
Last updated: 2026-06-01. Verified: 2026-06-01. Quarterly review for currency.