Window coverings serve a variety of purposes. Aside from providing privacy, they help protect furnishings from damage by the sun, aid in comfort control by offering insulation, and sometimes add significantly to the decor of a room.

Like windows, window coverings come in a variety of shapes and sizes. They include elaborate multi-layered window treatment systems that frequently cost more than the installed cost of the window itself.

On the other end of the cost spectrum is one of the oldest and most economical window coverings the roller shade. While the style of roller shades has changed over time, the fundamental construction and operation of the apparatus has remained essentially the same. It consists of a metal or wooden pole or roller around which a shade is wrapped. The shade is vinyl or a woven fabric which can be either translucent or opaque.

The roller is hollowed out for a long spring that is controlled by a ratchet. The shade is held in position by a pawl that latches into the tooth of the ratchet. When the shade is lowered, the pawl disengages, increasing spring tension. When the shade is raised the spring uncoils, reducing spring tension and allowing the shade to wrap around the roller. One of the biggest advantages of a roller shade is its ease of installation. It's as simple to install today as it was a hundred years ago. The process requires only a simple screwdriver, therefore making it one of the most popular choices among do-it-yourselfers.

The roller shade can be installed two ways: surface mounted (outside mount) on the face of the wall or inside mounted within the window opening. In either case, ease of installation is about the same. The basic difference is the brackets used. Most shades come with both types of brackets to allow for either method of installation.

Depending upon the type of installation employed, the mounting brackets are attached to the wall or window frame with screws. When attaching to wallboard or plaster, an expansion anchor should be used for a more secure connection. The bracket containing a hole is for the pin. The bracket that has a groove is for the spear. Once the brackets have been installed, insert the pin into the bracket and slide the spear into the opposite bracket.

There is little or no play for shades that are inside mount. They must fit within the opening provided. Therefore, unless the shade is the exact size, it will need to be purchased slightly larger than the opening and cut to fit. To make the shade narrower, simply remove the cloth, pull off the metal cap at the pin end the circular end as opposed to the flat end then remove the pin and cut the roller to size using a saw. Trim the cloth, align it parallel to the roller and reattach it. Replace the cap and tap the pin in with a hammer.

Some modern roller shades are adjustable. All one needs to do is completely roll out the fabric or vinyl, remove a portion of it from the roller and adjust the pole down. Reattach the material and trim the excess. Some vinyl models can be trimmed by perforating the material where it attaches to the roller and ripping it along a manufactured seam. These are really easy to work with.

Surface mount shades don't require the precision that inside mount shades do. In fact, they should overlap the window opening by a couple of inches on either side. Depending on the type of window frame involved, this variety can actually offer greater privacy than the inside mount.

If, after installation, the shade doesn't roll up fully or winds sluggishly, the spring tension needs to be increased. To tighten the spring tension, first roll the shade down about two feet and remove the roller from the brackets. Next, roll the shade up by hand and replace it into the brackets. Check it for proper operation by rolling it up and down. If the spring is still weak repeat the adjustment process.