Exterior home design coordination of attached housing can be important in developing a townhouse community so important that some residential developers retain interior design firms to help EXTERIOR DESIGN. The outside of a home must be as appealing as the inside, so the logical experts were interior designers. Exterior color coordination begins when the developer chooses the materials,such as brick,siding,roofing and shutters. After providing samples of the materials, the developer works with the designer to determine color tone and harmony.