In theatre, a platform is a stationary, standard flat walking surface for actors to perform on. Typically, they are built to be assembled modularly. They are often used to provide varying levels, to make a show more visually interesting. They are also used to separate areas on stage, and as seating bleachers. This is in contrast to scenery wagon

Scenery wagon

A scenery wagon, also known as a stage wagon, is a mobile platform that is used to support and transport movable, three-dimensional theatrical scenery on a theater stage. In most cases, the scenery is constructed on top of the wagon such that the wagon, and the scenery it supports, forms a single,...

s, which are mobile platforms that are supported by casters instead of feet.

Lids

Lids are typically made from a sheet of plywood

Plywood

Plywood is a type of manufactured timber made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured...

, although oriented strand board

Oriented strand board

Oriented strand board, also known as OSB and SmartPly , is an engineered wood product formed by layering strands of wood in specific orientations. In appearance, it may have a rough and variegated surface with the individual strips Oriented strand board, also known as OSB (UK) and SmartPly (UK &...

 is also sometimes used. Sometimes another layer is added on top of the plywood. Hardboard

Hardboard

Hardboard, also called high-density fiberboard , not to be confused with 'hardwood', is a type of fiberboard, which is an engineered wood product....

 is sometimes used as an easily replaceable and sturdy cover. Homasote

Homasote

Homasote is a brand name that has become synonymous with the product generically known as cellulose based fiber wall board, which is similar in composition to papier-mache, made from recycled paper that is compressed under high temperature and pressure and held together with a glue...

 is sometimes used because it is quiet and more comfortable to walk on. Occasionally, a layer of muslin

Muslin

Muslin |sewing patterns]], such as for clothing, curtains, or upholstery. Because air moves easily through muslin, muslin clothing is suitable for hot, dry climates.- Etymology and history :...

 is added on top of these materials, as it takes paint better than other options.

Framing

Framing is most commonly made of nominally 2"x4" lumber

Lumber

Lumber or timber is wood in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....

 or rectangular steel tubing, oriented so that its longer dimension is vertical, perpendicular to the lid. Framing is usually arranged to be at or near every edge of the lid. In addition, intermediate members (sometimes called toggles) are added. Common rules of thumb dictate that the lid should not overhang the framing by more than three inches, and that internal framing should be two feet or less apart.

Legs

Wooden framed platforms usually use 2x4 legs, which rest just inside of the framing, under the lid, with a cleat which supports the framing. Steel framed platforms are often built with brackets to affix legs made of steel pipe. When large numbers of platforms are being used together, a stud wall is assembled to support seams between platforms, instead of using legs at all.

Other

Often, platforms that are kept in stock have coffin lock

Coffin lock

Coffin Lock is a slang term for a blind panel connector often used in the performing arts to join together stage decks or scenery in a butt joint or cabinet and lid locks on road cases. These are typically two part connectors that draw together and lock...

s inset in their framing or lids, in order to fasten them to adjacent platforms. The legs or stud walls that support the platform typically require diagonal cross bracing, often made of very thin lumber.

Stock Usage

Many theatres maintain a 'stock' collection of platforming, which can be reused in any show. 4'x8' platforms are most common, although 6'x4' and 4'x4' are also quite common. These theatres also maintain standard sized legs, and often stair units which reach their standard height platforms.