Manufacturing, installation, cleaning, and usage all can cause a carpet to buckle or have ridges. In some cases, it is related to latex problems and delamination.
ERRORS IN MANUFACTURING
If the latex is stiff & brittle or limp & droopy this is how it may look
If the problem is inherent in manufacturing, then testing can be done for DIMENSIONAL STABILITY. DIMENSIONAL STABILITY does not have official standards. In years past a combined percentage greater than three percent was not acceptable. Furthermore a percentage less than 2.5 was required to consider the carpet good. Currently some mills would say that yarn style and woven backing material would be a factor in determining a higher acceptable percent on this test.
ERRORS IN INSTALLATION
The backside of the carpet above shows oblong stretch marks made from the nail of the tackless strip on the right or bottom-side, but not on the left side. Thus this carpet was stretched in the length only creating buckling in the length.
The temperature and humidity on the day that the carpet was installed could also have an effect on a carpet buckling and CRI STANDARDS for both temperature and power stretching are given below.
Concerning Temperature and Humidity with respect to Site Conditions the CRI105 - 1994 says this:
° and 95° F (18° C. and 35° C.) and the relative humidity Is between 10% and 65% and, if installing over concrete, the slab temperature should not be less than 65° F (18° C).
Concerning power-stretching, the CRI105 says:
Temporary Ripples, Waves after Cleaning
There is a temporary condition known as DIFFERENTIAL EXPANSION where the carpet has ridges. DIFFERENTIAL EXPANSION is quart in design of tufted carpet where backings expand at different rates. According to the IICRC, CCT Certification course instruction, a cleaner must inform the customer of the cause and tell them to stay off carpet in this condition and let it dry.