Jamb
The vertical sides — and the top “head jamb” — of the window frame that the sash rides against or seals to.
What it means for you
“Jamb depth” is the measurement that decides whether a replacement unit fits your wall; too shallow and it won't take a standard insert. Rot usually starts at the sill and climbs the jamb.
Where you'll see it
In measuring notes and depth specs; a common rot location at inspection.
Related terms
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