On a double-hung window, the bottom rail of the upper sash and the upper rail of the lower sash, where the lock is mounted. Or, on a sliding window, the vertical sash rails that overlap when the window is closed.
Millwork Definitions
Check rail
We fabricate any type of architecturally specified wood. To help you get your bearings – there are a thousand definitions in our guide here. Contact us to have the custom pieces made to order in any species you request.