Capet is a material. Over time material can expand or shrink when exposed to different room temperatures, high traffic, over cleaning or it could be due to improper installation. Most carpet will expand under these conditions. If your carpet has wrinkles in the open ares of more than one room or doorways it it usually improper installation. A power stretcher must be used on residential stretch in action-back carpet. If not your carpet will eventually loosen on the floor and look similar to the picture here. Our Company specializes in carpet restretching and repairs. Call 770-217-0545 for a free estimate.