Lets say that manufactories say that there carpets 'should' be stretch fitted or fully bonded. So with them saying that then starting at the top is wrong as you void there guarranty. (your not stretch fitting) But at the end of the day im a fitter like you lot and i start at the top on some jobs and bottom on others. You tend to chose your jobs. Anyway, once shown fitting from the bottom up most prefer this method. But like i say it is more down to the job and the carpet your fitting.