Flats, short for Scenery Flats, are flat pieces of theatrical

Theatre

Theatre is a collaborative form of fine art that uses live performers to present the experience of a real or imagined event before a live audience in a specific place. The performers may communicate this experience to the audience through combinations of gesture, speech, song, music or dance...

 scenery which are painted and positioned on stage

Stage (theatre)

In theatre or performance arts, the stage is a designated space for the performance productions. The stage serves as a space for actors or performers and a focal point for the members of the audience...

 so as to give the appearance of buildings or other background. They are also called backdrops or backcloths.

Flats can be soft or hard covered. Soft-covered flats (covered with canvas or muslin) have changed little from their origin in the Italian Renaissance. Hard-covered flats with a frame that is perpendicular to the paint surface are referred to as studio, TV, or Hollywood flats. Flats with a frame that places the width of the lumber parallel to the face are called New York or Broadway flats.

Usually flats are built in standard sizes of 8, 10, or 12 feet tall (8 feet (2.4 m), 10 feet (3 m) or 12 feet (3.7 m)) so that walls or other scenery may easily be constructed, and so that flats may be stored and reused for subsequent productions.

Often affixed to battens

Batten (theater)

In theater, batten refers to a long metal pole suspended above the stage or the audience from which lighting fixtures, theatrical scenery, tabs or other curtains may be hung...

 flown in from the fly tower or loft for the scenes in which they are used, they may also be stored at the sides of the stage, called wings, and braced

Brace (theatre)

In theater, a brace is a sliding piece of wood or metal with a 'butterfly' winged nut to make it longer or shorter to fit the flat used to stabilize a flat set piece such as a flat. The nut is used ,so that it can be changed more quickley than a screw to the floor during a quick change. Usually, a...

 to the floor when in use for an entire performance.

Some casts have a tradition of signing the back of flats used on their production.

Parts of a flat

Rails are the top and bottom framing members of a flat. Rails run the full width of the flat [4 feet (1.2 m) for a 4'x8' flat (4 foot)].

Stiles are the sides of the flat frame. The length of the stiles is the full height of the flat, minus the combined width of the rails [7 in 7 in (2.31 m) for a 4'x8' soft-cover flat (4 foot) constructed of 2+1/2 in rails].

Toggles are cross pieces that run between the stiles. The number and placement of toggles depends on the type of flat. The length of the toggles is the total width of the flat minus the combined width of the stiles [3 in 7 in (1.09 m) for a 4'x8' (4 foot) soft-cover flat constructed of 2+1/2 in stiles].

Corner blocks are used to join the corners of a soft-cover flat. They are normally made of 1/4 in AC plywood, and are triangles with corners of 45, 45, and 90 degrees. They are most often made by ripping the plywood at 6+1/2 in and then mitering it at 45 degree angles to create triangles with 9 inches (22.9 cm) legs.

Keystones join the toggles to the rails of soft-cover flats. They are 8 inches (20.3 cm) long, and normally ripped to the same width as the toggles (usually 2+3/4 in) on one end, and 3+1/2 in on the other, forming a shape similar to the keystone of an archway.

Straps can be used in place of keystones. They are 8 inches (20.3 cm) long and 2+3/4 in wide (same as toggle) rectangles. They are easier to construct than keystones, but not as strong.

A 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...

may be used to join securely adjacent flats.

Styles

Broadway or stage flats are generally constructed of 1 inches (2.5 cm) x 3 inches (7.6 cm) nominal [3/4 in x 2+1/2 in actual] pine boards. The boards are laid out flat on the shop floor, squared, and joined with the keystones and corner blocks. The keystones and corner blocks are inset 1 inches (2.5 cm) from the outside edge, which allows for flats to be hinged or butted together. They are then glued in place, and stapled or screwed down. The flat can then be flipped over and covered with muslin or lauan. Toggles in a Broadway flat are placed on 4' centers.
Broadway flats can also be constructed using half lap joints, also known as dados. Dados forgo the use of keystones and corner blocks, and joins stiles, rails and toggles, by removing 3/8" inch of material, from pieces to be joined together, to create a simple half-lap joint, that is then glued and stapled. Dados can be made using a radial arm saw and a dado stack (dado stacks have two outer circular saw blades and several "chippers" sandwiched between them to allow more material to be removed per pass of the blade), or a table saw and a dado stack. The set up of a dado stack is about equal to the amount of time prepping keystones and cornerblocks. The amount of math involved in figuring out a cut list is lessened, because the length of your stiles, rails and toggles are equal to the face of your flat.
Hollywood or tv flats can be made in various thicknesses to suit a particular design, but are most often made of 1 inches (2.5 cm) x 3 inches (7.6 cm) nominal [3/4 in x 2+1/2 in actual] or 1"x3" actual pine boards. The boards are laid out on edge on the shop floor, the ends are glued together and staples or screwed. Keystones and corner blocks are not normally used. Once assembled, the flat can be covered with 1/4 in or 1/8 in lauan, which is glued on and stapled. The toggles in a Hollywood flat are placed on 2 foot (0.6096 m) centers.

Hollywood flats may receive a muslin skin over the lauan face. The face is covered in a mixture of water and white glue, the muslin is applied and the entire flat is covered with the water/glue mixture again, to shrink and attach the muslin.

Discussion

Each type of flat has advantages and disadvantages. Broadway flats generally require less lumber, and their structural integrity does not depend on the their skin (thus they can be covered with cloth). Hollywood flats require additional stiffening if they are to be soft-covered. Broadway flats are easier and safer to fly, and take up less space in the air. They are also easier to store, as they are only about 1 inches (2.5 cm) thick. Hollywood flats are useful for their inherent rigidity (since the pine boards are on edge, they are resistant to bending). They are also easy to join together; their frames can simply be screwed together. Broadway flats require some sort of stiffener, hinge, or batten to join them. Hollywood flats can also be made in a variety of thicknesses, while Broadway flats are limited to more or less 1 inches (2.5 cm) in thickness. Either type of flat can be made double sided, but it is easier to do with Hollywood flats: one simply flips the flat over and faces the other side. A Broadway flat must first be assembled with keystones and corner blocks (but without glue) and skinned on one side, then the keystones and corner blocks may be removed and the other side skinned.