I wished I had known of problems with lippage and warpage of 4 foot length tile!! What a nightmare! First I'll tell you that I used a reputable contractor, he's done beautiful work for me in the past. Admittedly, he's never done 4' lengths; but this guy is a bull and will not let go of a problem until he solves it! There's a bow in every piece of this length tile (6" x 4'). Even using Tucson clips to keep each tile level with the next, the bow is so strong that areas of my job 'lifted' away from the substrate! Naturally this makes the grout pop out and now in same cases, stepping on 'LIFTED' area, cracks the tile in half! Weights, 5 gallon buckets of water, etc, had to be used to hold all the clipped tile while the mastic dried...this worked sometimes, sometimes not at all. The memory of the 'bow' in the tile won out! The tile store's 'help' to me was to give me an article written in "TILEmagonline.com Dated October 2007 by Katelyn Simspon Article Title: "warpage, Lippage, and Retaed Challenges Yup, that was so much help.......AFTER we made design choices and purchased! I'm writing letters to all board members of DAL TILE, this is unacceptable with all the money we have spent on 825 sq feet of tile, supplies, and labor. We are planning our gracefully aging and I can tell you, we have loads of toe trips on this floor! The thought of our hard earned saved up cash for comfort in aging has been trashed. We moved on to finish rest of project non the less, hoping the floor would 'settle' over time....ha! I've cried many tears and now I'm ready to muscle up and see if I can get any compensation from this company...gees! Just the way I want to spend my extra time. Get ALL the facts before choosing your flooring and for sure the company you use!