When we formed the second lift of a 94-foot wall we found that the first lift was about one inch too long. We were using prefabricated forms and don't think that much variation should have occurred. Are all prefabricated forms that bad?
Prefabricated forms are normally quite accurate. Your experience could easily occur even if all of the forms had been exact. A 94-foot wall is likely to have 47 joints. A total error of one inch spread over that many joints is an average excess of only 0.021 inch, about the equivalent thickness of a couple of business cards. The small amount of grout buildup that can normally occur on the edge of forms would be enough to cause the amount of error you experienced. A dimensional gain could also be caused by lack of care in connecting the form hardware. Usually problems of dimensional gain are experienced only when carpenters are unfamiliar with the kind of forms being used. The best way to avoid the problem is to instruct them to check the dimension of the wall about every ten panels. This permits them to compensate for any dimensional variances before the gain becomes a large and serious problem.