| | | | | | | | |
| AWC Holding Company | | Delaware |
| Building Systems de Mexico, S.A. de C.V. | | Mexico |
| Cornerstone Building Brands Canada, Inc. (f/k/a Gienow Canada, Inc.) | | Ontario, Canada |
| Cornerstone Building Brands Services, Inc. | | Delaware |
| Cornerstone Latin American Services, S.R.L. | | Costa Rica |
| Environmental Materials, LLC | | Delaware |
| M.A.C. Métal Architectural Inc. | | Quebec, Canada |
| Mastic Home Exteriors, Inc. | | Ohio |
| Metal Sales Manufacturing LLC | | Kentucky |
| Metal Sales Manufacturing Transportation, LLC | | Indiana |
| Mitten Inc. | | Ontario, Canada |
| MW Manufacturers Inc. | | Delaware |
| MWM Holding, Inc. | | Delaware |
| Mueller Supply Company, Inc. | | Texas |
| NCI Group, Inc. | | Nevada |
| Ply Gem Industries, Inc. | | Delaware |
| Robertson-Ceco II Corporation | | Delaware |
| Variform, Inc. | | Missouri |