In the early 20th century, some house designers started using prefabrication. Sears, Roebuck & Co. first marketed their Sears Catalog Homes to the general public in 1908. Prefab techniques became popular after World War II. First small inside rooms framing, then later, whole walls were prefabricated and carried to the construction site. The original impetus was to use the labor force inside a shelter during inclement weather. More recently, builders have begun to collaborate with structural engineers who use finite element analysis to design prefabricated steel-framed homes with known resistance to high wind loads and seismic forces. These newer products provide labor savings, more consistent quality, and possibly accelerated construction processes.