Research paper Historically, most dog houses have been hand-made from whatever materials could be scraped together. This has changed over the last century, especially since World War II, since most dog houses today are commercially mass produced in factories. Contributing factors here include reduced costs and greater availability of plywood, framing lumber and roofing materials as well as the introduction of new materials such as foam sheet insulation, pressure-treated lumber, and weather resistant plastics and wood finishes. Advances in machinery and manufacturing techniques have also played a huge role in this. Of course, the main growth of the dog house industry has been the huge increase in pet ownership. Results from the APPMA 2005-2006 National Pet Owners Survey showed pet ownership at its highest level ever, with 63 percent of all U.S. households owning a pet. About half of all households own a cat, dog, or both. Wood has been the preferred material for dog houses over the years due to its ready availability, low cost, effortlessness of working, insulating properties, and structural reliability. The demand for wood dog houses has been accommodated over the last quarter century or so by the emergence of a number of medium-to-large sized companies that specialize in wooden houses. Some of the big names in the business today include Merry Products, Ware Manufacturing and Blythe Woodworks. Some companies - such as Merry Products - leave the actual construction to Chinese manufacturing plants and focus solely on marketing, distribution and customer service. Don't be too surprised to see this overseas manufacturing trend increase in the future. Plastic dog houses were introduced in the 1960's and have steadily grown their market share since. In some cases, the companies producing plastic dog houses