Business OverviewLike windows, doors also rank number six as the most frequently completed home improvement renovation. Once again, modern manufacturing methods and materials have helped to fuel the desire for this type of home improvement. Newly installed doors not only have better safety and insulation features, these doors are also highly attractive and can improve the appearance of the home for a relatively small investment. Due to the fact that this is a competitive industry, you may want to consider specializing in one particular type of door or become an exclusive agent or representative for one door manufacturer. Specialization in any industry will generally result in lower wholesale product costs and higher returns, in terms of both product and service demand. Do not overlook the apartment or condominium market for this product. Many of these buildings were constructed during the early Ã¢â¬Ë80s, while the construction industry was booming, and the quality of the doors at that time was very inferior to today's doors.