Structural connections: Timber frames are typically constructed with joinery and doweling alone, seldom with the use of glue or nails. These types of semi-rigid structural joints allow the timber structure to resist bending and torsion while under high compression.[4] Structural stability is further ensured through the use of heavy beams and roofs, which weighs the structure down.[14] The lack of glue or nails in joinery, the use of non-rigid support such as dougong, and the used of wood as structural members allow the buildings to slide, flex, and hinge while absorbing shock, vibration, and groundshift from earthquakes without significant damage to its structure.[4] Walls: The common use of curtain walls or door panels to delineate rooms or enclose a building, with the general de-emphasis of load-bearing walls in most higher class construction. However, with the reduction in availability of trees in the later dynasties for building structures, the use of load-bearing walls in non-governmental or religious construction increased, with brick and stone being commonly used.