TV production spaces
Nov 1, 2008 12:00 PM, By Antonio Argibay, AIA
The first article in this two-part series helps you plan TV production areas.
It is not unusual to build the outer wall with concrete masonry units for larger TV studios, as the outer wall may be the outside wall of the building itself. However, usually — especially in the smaller to medium-sized studios — the wall is made of steel studs, with multiple layers of gypsum board on each side, as required to meet the acoustic design criteria. The cavity between the gypsum boards is then filled with fiberglass or mineral wool for cavity absorption.
The interior wall, often referred to as the liner wall, is almost always made with multiple layers of gypsum board on the studio side and fastened to metal framing, with the cavity filled with fiberglass or mineral wool for absorption. The inner wall, unlike the outer wall, is unfastened at the top. It must remain independent of the structure to maintain isolation, and, as such, is unstable structurally. The inner wall maintains structural integrity by lateral isolators called sway braces. There is a large variety of products that are designed to restrain lateral movement of the inner wall. Generally, these products are attached to the outer wall by means of a neoprene cushion that prevents a hard connection between the two walls.
It is important to note that when designing tall walls, special consideration must be given to structural requirements, such as the ratio of wall thickness to height, location of isolators (when required) and their coordination with support points for rigging. As mentioned above, the walls are largely finished with soft, absorbent materials, which are then protected with an inexpensive material such as wire mesh. However, this wall treatment must be interrupted at frequent intervals with the installation of horizontal wood members that can be used where screws are needed.
Doors and other wall openings
The weakest link in the wall system is the need for openings to make the space usable. The number of doors and their sizes is determined by several factors. All doors are there for a purpose and fall into one of two categories: doors for people to use and large doors commonly known as elephant doors.
Depending on studio size and use, people doors are placed in convenient locations in quantities necessary to satisfy safe egress. Studios that have audiences require specific planning so that they have enough doors to handle the occupancy and take into consideration the distance from the audience to the doors. Others need only one or two entrances for people, depending on the size — one typically close to the support spaces, such as control rooms and dressing rooms, and the other close to the staging area to be used by stage hands and technicians who access the studio. Elephant doors are used to move scenic elements into and out of the studio from the staging area. The smallest recommended size is 10ft × 6ft, typically used in small production spaces that have infrequent changes of scenery or don't require movement of tall sets and motor vehicles. A more appropriate size for those studios is a minimum of 12ft × 8ft. For specialized productions, such as those for filmmaking, doors should be much larger than the minimum.
When doors are opened, outside noise immediately penetrates the studio space. While sometimes this is not acceptable, it is at least manageable. In such cases, the door should be a true acoustic door with a sound transmission coefficient (STC) of at least 51, which, while it will not protect from somebody knocking (impact), will give substantial protection against airborne sound. We recommend using two doors of lesser quality to create a vestibule, or sound lock, which offers the best protection.
Sound locks for elephant doors are impractical due to space constraints. In smaller doors, up to 12ft × 8ft, it is practical to provide one set of doors on the outside wall and another on the inside wall, thus creating a zero clearance sound lock. Doors larger than that become increasingly heavy and need systems to mechanically aid their operation. The more popular doors are motorized, sliding or vertical-lift doors with cores of 4in to 6in, partially filled with concrete or other mass-producing component, depending on the desired STC rating.
Other openings that should not be overlooked are those that bring in wires for power and broadcast. Typically, power is brought inside in conduits or electrical wire-ways. These materials must be interrupted so that the rigid conduit does not bridge the independent walls or make a hard connection between the two. To eliminate bridging the walls, it is necessary to use a flexible conduit through the penetration, including proper grounding to ensure continuous ground for the power system. The broadcast wiring is usually in a cable tray in order to provide quick and easy access to the substantial amount of wiring. The cable tray should be stopped at either side of the wall, allowing the wires to penetrate through a metal box or conduit that is filled with easily removable, compressible material that seals the opening.
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