In the 2002 revision of the Institute of Inspection, Cleaning and Restoration Certification (IICRC) S100 Standard and Reference Guide for Professional Carpet Cleaning, there is a residential cleaning frequency chart that suggests professional cleaning every 12 to 18 months for heavy use areas and every two years for the remainder of carpet in the home when light soiling conditions prevail.
Normal soiling increases the frequency to six to 12 month intervals for heavily used areas and annually for other carpeted areas in the home.
Special conditions, such as families with pets, occupants who smoke and homes with large families, all merit cleaning in traffic lanes as often as every two months and entire house cleaning four times a year. (I.I.C.R.C.)
Regardless of how often you choose to use them, our experts agree that professional steam cleaners are hands-down necessary — you shouldn’t attempt to steam carpets yourself. Only steam can effectively lift dust from deep within your carpet, Wilson says — if left there, it will wear down and rip the carpet’s fibers. But only professional machines can truly zap all the steam’s moisture from the carpet when you’re done cleaning. The results of trying to do it yourself can be sickening.(Huffington Post)