With many pieces of furniture, legs and undersides can be hazardous to the health of your carpet. Whether it's from heavy pieces creating permanent indentations in the flooring or from rough legs tearing or catching on the fibres, sometimes it's necessary to take measures to protect your carpet from the legs of chairs. Use a few simple precautions to make sure those chairs don't leave their mark permanently.
Turn each chair on its side. Cut small circles or squares of felt (depending on the shape of the legs) just big enough to cover the legs of the furniture. Attach these pieces with a small strip of heavy-duty, double-sided tape or glue in place with wood glue if you don't mind attaching them permanently. The felt will protect the carpet from some of the compression of fibres and from scratching and catching of the chair legs, if they're rough.
Fit the legs of chairs that are moved on a regular basis with wheels to prevent them scraping against the carpet. Purchase wheel kits, complete with instructions, at hardware shops or office furniture sellers. Follow the manufacturer's instructions to install them.
Place an area rug beneath chairs that you move often but can't fit with wheels, such as dining table chairs. This will guarantee that the permanent carpet beneath the rug won't be affected, but the rug itself may be forfeit. Use this solution with an inexpensive rug; it's especially good if you're living in a rental home and want to leave things as they were when you found them.
Use a protective cup under narrow chair legs. These are available at hardware stores and large furniture stores and come in a variety of shapes and materials, from plastic bowl shapes and wooden discs to rubber stoppers that fit firmly over chair legs, sticking in place even when you lift them. These will protect the carpet from rough spots on the chair legs while spreading out some of the weight.
Move large chairs periodically, even a little bit, if they're not moved around on a regular basis. This will prevent permanent compression of the carpet fibres beneath the legs of the chair. Plan to move large chairs every three months or so.