Photo by Andrey K, via Unsplash
Jam (Door or Window)
The vertical (can be horizontal for a window) portion of the frame that allows a door to be secured.
Fort Thomas Avenue, Fort Thomas, KY by Warren LeMay , CC BY-SA 2.0, via Flickr
Jerkinhead
A sloping or hipped end of a roof that cuts off a gable.
Photo by Anıl Mustafa Özdemir, via Pexels
Jetty
A projecting part of a building, as the upper story of a timber house.