Learning from Others' Mistakes by William A. Lotz, P.E. The architect required foil-backed gypsum wallboard as the combined vapor barrier and interior finish. The specifications read "Provide aluminum- foil-backed tape behind all joints to maintain vapor barrier." I have no idea how the contractor could possibly have done what the architect's specifications required. However, the contractor had a legal obligation to either follow the drawings or point out in writing that the detail was impossible and ask for a change. The contractor, in this case, chose not to make an issue of the but learning from others' problems is much less expensive and traumatic. Learning the Easier Way There are many inexpensive ways to learn. Attend at least one builders' conference or workshop