Interior designer implies that there is more of an emphasis on planning, functional design and the effective use of space, as compared to interior decorating. An interior designer in fine line design can undertake projects that include arranging the basic layout of spaces within a building as well as projects that require an understanding of technical issues such as window and door positioning, acoustics, and lighting. Although an interior designer may create the layout of a space, they may not alter load-bearing walls without having their designs stamped for approval by a structural engineer. Interior designers often work directly with architects, engineers and contractors.