New Jersey-based manufacturer GAF Materials Corp. is planning a new warehouse in LaPorte County. Ground has been broken for a 200,000-square-foot facility to house office and warehouse space in Michigan City’s Millennium Business Park. GAF already operates a shingle manufacturing plant in Michigan City. The new building will be built on a 45-acre site, with at least 23 acres for concrete storage by Dallas-based Mohr Capital. The new facility is expected to be complete by December and could create up to 50 new jobs.