A contractor may be thoroughly familiar with forming for structural adequacy and yet find himself totally unable to achieve the desired architectural finish. To produce good architectural concrete, certain essential details must be incorporated into the structural forming system. A lack of attention to these details invariably results in faulty work. Three forming details of plywood systems that most often cause problems due to moisture leakage are: face butt joints- an impervious liner attached to the structural plywood will reduce the possibility of leakage if the liner butt joints are offset from the plywood butt joints; corner butt joints- the best method employs a closed cell compressible foam gasket material to prevent leakage; construction joints- a rustification must always be used at the top of the previous placement. As the next casting is formed, gasket material is placed between the face of the rustication and the existing concrete to eliminate leakage underneath the rustification. Fiberglass-reinforced plastic or steel forms normally present fewer joints, which simplifies the problem of sealing. This is especially true where columns and beam forms are designed as U-shaped members. These types of forms are usually flanged at all joints and moisture loss is prevented by the use of compressible closed-cell gasket material at these points. When lumber is used to produce a boarded surface, consideration must be given to the degree of uniformity desired in the finish. The lumber should be dipped in a wood sealer to ensure that all sides are completely sealed, thus preventing the possibility of form warpage should an uncoated side become wet. Fiberglass-reinforced plastic liners are normally screwed or glued to the structural forming system. Gasket material is required at corners and bottom of placements. Caulking compounds or epoxy are used to prevent leakage between liner sections.