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There are several different kinds of rug backings and it is important to verify that a rug has an appropriate backing for the use that it will undergo. Rug backing needs to allow the carpet to breathe, which means the backing needs to allow air, moisture, and gases through. If a rug or carpet does not have an appropriate backing for the intended use, then damage is likely to occur both to the rug and to the flooring underneath it. The full latex backing found on many bathmats is the most notorious for ruining the floor underneath. This type of latex backing is used on rugs for bathrooms for two reasons. First is that it completely stops moisture from getting through, which is important to protect the under floor from serious water damage. The second reason is that this type of backing offers a significant amount of grip to keep the mat from sliding, particularly on tile surfaces. However, latex backing does not allow the rug or under floor to breath at all. For this reason, it is a good idea to pick up latex backed bathroom rugs and hang them to dry after every shower. An easier alternative is to use permeable material that is used to stop any rug from sliding. This non-skid rug underlay is usually available at most home supply stores, and can be used with any kind of rug and rug backing to stop skidding.
Many new area rugs and carpets feature "Action Back" backing. This type of backing is usually heat-set onto the back of the rug. It was designed to stand up to professional steam cleaning without degenerating from the heat and moisture. Action Back has high performance for allowing carpeting to breathe and protecting the floor underneath.
Woven backing is also proven to allow plenty of air, moisture, and gas transference against any hard floor. Woven backing is often found on handmade wool antique rugs of fine quality, as it works well with the wool and lends itself easily to the handmade process.
Many machine made wool rugs use heat-set backing. Heat-set backing has good breathability and long lasting qualities. It is generally the best alternative to woven backing, for manufacturers that do not hand make their rugs. Heat-set backing is unlikely to be used on antique rugs. This is a good way to tell whether or not an area rug is antique or vintage-- the older the rug, the more likely it will have woven backing. Antique rug dealers are a font of knowledge on older types of rug backings, such as those used in antique Oushak rugs and antique Persian rugs; both of which have rich histories in rug making. Before buying a new carpet, consider what type of floor will be used underneath, and talk to the rug dealer to find the right kind of rug backing to protect the floor.
