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.
The final acoustical consideration is the noise generated by the air-conditioning/ventilating system, which is the biggest source of noise within your space, once the proper isolation is in place. The two sources of noise related to ventilation are equipment noise and air noise at point of discharge.
Studio floor
The studio floor is one of the most important components that make up a studio. Without the necessary degree of floor level, cameras will roll by themselves, causing uneven images. If the floor contains bumps and imperfections, the camera will move abruptly as it hits mounds and valleys. These two aspects of the TV floor are referred to as level and true-to-edge. Typically the level is a maximum 0.25in over a distance of 50ft. True-to-edge is the local flatness of any given area, which should typically not exceed 0.0625in, the maximum gap in any part between the floor and a metal straight-edge. A good way to inspect this is with a long, straight metal tube. Shine a light behind it to look for gaps and measure them with thin plastic, such as a credit card. If the card fits under the tube, the floor level is unacceptable.
Most floors are cast in concrete, a material that cannot achieve those tolerances. So how do we surmount this problem? To do that, turn to self-leveling concrete toppings or troweled, cementitious toppings. In selecting a solution, it is best to know how the floor will be finished by scenic elements (vinyl tile, wood, epoxy paint, back-painted plastic sheets, etc.). Some self-leveling toppings, however, can be used as a finished high-gloss floor (Stonlux). Others, such as Ardex, are self-leveling but may require grinding to meet the flatness criteria and are not finished floors. In the U.S. market, Dexotex is the better known manufacturer of hand-troweled finished floors.
Not all production environments are suited for a concrete finished floor, due to its inability to accept nails used to secure scenic elements that are often made of wood. In those instances, you could use floors made from medium density fiberboard (MDF). The installation of this material, an organic material that absorbs moisture, must be carefully coordinated with the moisture level in the concrete. It is typically installed in a staggered pattern over a series of level, water-sealed wood strips spaced 16in on center, with the void between the strips filled with cement. It is best to spline the edges of one board to the other to ensure the floor level from one to the other, and then finish the flooring system with a light sanding.
Finally, the structure of the floor has to be taken into consideration. It should always be decoupled from the adjacent floor slabs. If the studio is at ground level (and there are no recurring impact noises that shake the ground), it will suffice to provide a joint between the studio slab and others adjacent to it. In other cases, such as in studios with occupied spaces below and in situations where it isn't structurally feasible to separate adjacent slabs, a floated floor is the only solution to ensure isolation from airborne and structure-borne noise, such as vibrations and impact noise like hammering.
The two primary types of floated floors and methods of building them are spring-isolated and resilient-mounted. The spring-isolated floor consists of a steel-reinforced concrete slab cast on top of the structural slab, with isolators spaced along its extents at even intervals, typically 4ft. After a minimum of seven days of curing, the slab is jacked up by turning spring-tightening screws from above the slab. This solution is relatively expensive and, for optimum performance, should be specified only through close coordination with the structural engineer and the acoustician.
The resilient-mounted system is less expensive, does not require jacking up and requires less curing time but is more limited acoustically, providing largely structural decoupling. Typically, it is a system of neoprene or resin-covered fiberglass cubes covered with plywood and has a concrete slab poured over it, with only minimal mesh-type reinforcement. Both systems should be specified by the acoustical consultant based on the specific project requirements.
Wall construction
Figure 2. An acoustically isolated wall and floor construction are important when designing a TV studio. The wall system provides lateral acoustical protection from adjacent spaces.
Click to enlarge
The wall system in a studio provides lateral acoustical protection from adjacent spaces. (See Figure 2.) Additionally, the walls provide places on which to secure scenic elements that are usually tied above or on the studio floor and braced laterally to the wall. They are also treated with absorbent material to deaden the sound in the room.
Typically, studio walls are built of two walls that are, ideally, completely independent. This decoupling of walls is a primary requirement for acoustical isolation and is simple in concept. However, it is more difficult in practice, especially if it is a high wall. This double wall is designed so that the outer wall of the studio extends from the floor to the underside of the structure and is tightly sealed where penetrated by ducts, conduits and other structural members. The inner wall is built on the isolated or decoupled floor slab to ensure it will not vibrate along with the unisolated structure. This separation further ensures that impact on the outer wall will not be transmitted structurally.
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