Re-attachable structural assemblies incorporating complementary area fastening elements comprising hook and loop elements over extended rigid contact surfaces between structural members of an assembly are disclosed for use in the construction industry in relation to: temporary formwork for casting concrete; precast concrete components for permanent installation of finished surfaces; and, fabricated floor and wall systems including joists, sub-floors, and floor covering surface units. The use of synthetic hook and loop attachment systems affords significant savings in time, labor, and frequently in materials, particularly in the temporary formwork application.