English medieval timber roof system used when a long span was needed. Not a true truss, the construction is similar to corbeled masonry (&see; corbel) in that each set of beams steps upward (and inward) by resting on the ones below by means of curved...

Hammerbeam roof, in architecture, the name given to a Gothic open timber roof, of which the finest example is that over Westminster Hall (1395–1399). In order to give greater height in the centre, the ordinary tie beam is cut through, and the portions...