Louver - Slats contained within a shutter panel. Most shutters contain horizontal movable louvers, but some shutters use fixed louvers. Vertical louvers are used in some contemporary or speciality designs. Exterior shutters can use movable louvers, but fixed louvers are best for preventing water from penetrating the shutters.
Traditional interior shutters use 1-1/4" louvers, while most plantation shutters use either a 2-1/2", 3", 3-1/2", or 4-1/2" louver. Louver sizes are best determined by the size of the window, depth of the window, and style of the house. Larger louvers (sometimes incorrectly refered to as levelors) use more space between louvers, allowing for more visability and light through the open louvers.
Louver tension is a big consideration when comparing interior shutters. Louvers in shutters without properly tensioning will ultimate fall to the down position as the shutters age. An interior shutter without tensioned louvers is dead and useless.
Some companies feature a "tension screw" that is located on the side of each shutter panel. One tension screw is necessary for each louver section. This is commonly used as a sales tool so that customers can insert a screwdriver and adjust the louver tension if desired. Adjusting the tension screw ultimately becomes necessary on a regular basis as the shutters age. Louvers then within a single shutter unit will almost never have a uniform tension, giving them an undesired look and feel.
Poly, vinyl, faux wood, and synthetic shutters usually have an extremely tight louver tension. It is then difficult to put the louvers exactly in the desired location and the rotation of the louvers is difficult.
Horizon Interior Shutters and ShutterLand Shutters both use a split nylon pin tension system that give the louvers a uniform tension that will remain constant for the life of the shutter. This technique requires no maintenance.
Shutters can also be made with fixed louvers that are not movable and must remain in one position. Generally, louvers are fixed at an angle to block direct sunlight and allow for ventilation. Fixed louvers shutters are made with no tilt bar.
For an online source for interior shutters, see ShutterLand Interior Shutters, or Horizon Interior Shutters