The simplest of interior wall panels is the basic flush panel. It is a 20-50mm thick panel composed of a solid, composite, or joinery composition with a finished front surface that is held in place between the back of an exterior panel, a mounting angle strip bolted to the inner frame profile slots, or battens mounted in/along the inner profile slots and front cover strips. In some cases friction alone is used to hold panels. The panels themselves may have no attachment mechanisms or elements but may be fashioned with a 10mm groove for concealed spring or slide batten attachment, alternating side and bottom flanges for use with recessed front cover strips, or 10mm upper and lower back face flanges for pop-in mounting with somewhat flexible materials.
Common solid materials are pre-finished wood, fiber-cement board, plywoods or wheatboard, alloy, ceramic, polymer foam, cork, natural linoleum, or stone. Some of these may technically be composite materials are are uniform throughout and treated as a solid material in panel fabrication
Composite panels are usually composed of two or three laminated layers with a core layer making up most of the composition -usually plywood, wheatboard, fiber cement, or Masonite- with a laminated finish material on the front face -commonly wood and stone veneers, finished Masonite, natural linoleum, cork, or textured sheet alloy. Some composite panels may use a soft core material -polymer foam or cork- with a rigid back sheet of plywood or fiber-cement to reinforce it. Some may also feature a back layer of insulation, usually for added sound insulation.
Joinery panels are usually made of a combination wood materials that are textured or carved in addition to different finishings. They may be made of joined sets of hardwood planks or employ a frame -usually made to compliment the cover strip materials- which supports multiple wood inset panels. They can be made of many material combinations but most often will be made of wood.