Carpets should be stretched and then cleaned. The reasons for this include, first, that a loose carpet may bunch up while the cleaner's wand is going over it, hindering its cleaning ability. Second, wrinkle lines that form when a carpet has been wrinkled too long may be removed through cleaning.
Stretching a carpet requires specialized tools, including a power carpet stretcher, which is a very long pole that braces on one side of the room and uses a lever to stretch the carpet in the opposite direction. A smaller version, known as a knee stretcher, is also essential to getting the corners to look just right. While these tools may be purchased or rented, the process is more complex than it initially appears. Some people may be better off hiring a professional to perform this work.
Many carpet-cleaning services, such as Carpet Pro Cleaners, offer carpet stretching as a part of their services. More specialized providers, such as Nip Tuck Carpet Repair, also exist and generally have relationships with local carpet cleaners since the services are related.