Checking: Longitudinal splits in a log resulting from internal stresses caused by drying.
Grain: Direction of arrangement of fibres in wood.
Header: Structural log that supports other logs (such as joists or rafters where they are cut around a horizontal opening, such as a window or door.
Lateral Groove: Groove cut the length of a log (under side) so that it will fit onto the log sitting below.
Lintel: Horizontal log spanning an opening in a wall, such as a door.
Mortise: Square or rectangular recess cut into a log where a tenon will fit.
Notch: Recess cut into a log, where another log will fit into.
Plate Log: Log on the top of a wall that supports the rafters.
Purlin: Horizontal roof beams, running parallel with the wall.
Rabbet: Three sided groove cut into log.
Ridge: The top-most purlin.
Scriber: Tool used to mark parallel lines to match log-on-top-of-log.
Sill: Bottom log for wall, door, or window.
Tenon: A square or rectangular extension at the end of a log to fit into a mortise.
Truss: Part of the roof support system – supports purlins and ridges.