Carpet backing is exactly what it sounds like: the back of a carpet. It is the section of a carpet which does not face up, so consumers rarely interact with it. However, carpet backing is extremely important, providing shape, structural stability, and protection to the carpet it backs. There are a number of different styles of carpet backing, and it can be made from an assortment of materials, ranging from natural fibers to polyurethane.
There are two main components to carpet backing, which can vary from carpet to carpet. The first is primary backing, which forms a structural element of the carpet. It is the coarse material through which the fibers of the carpet are woven or tufted. Secondary backing is not structural, but it provides support to the overall carpet, and it may help to insulate the carpet from moisture, bacteria, and mold which could seep up from the floor below; it tends to be less coarse, since it is not a substrate for tufted material.
There are a number of things to consider when buying carpet, and backing material is an important one. Many companies make carpets with backing that it supposed to resist mold, mildew, rot, and other problems which can plague carpeting, and some also also pride themselves on using environmentally friendly backing, which can be made from recycled carpets or natural materials. Organizations which promote carpet recycling point to the millions of tons of carpeting which are discarded worldwide annually as a potential environmental issue which should be addressed; consumers can help encourage recycling by asking for recycled materials.
In addition to carpet backing which is built into the carpet, many companies offer carpet padding which they may call “carpet backing,” since it is installed under a carpet. Typically, carpet padding is designed to pad the carpet, provide more insulation, and prevent mold and mildew from setting in. It may be treated with various substances to achieve these goals; some carpet padding can offgas with strange fumes, which is why people like to allow carpet to settle for a few days before using a space.
On a throw rug, you may want to take a look at the carpet backing before purchase. You may see that only the primary backing is present, in which case you can clearly see the methods used to construct the carpet. If the carpet has a secondary backing, you might want to ask what it is made out of and how to care for it, as well as the carpet itself.