See FAR Subpart 2.1 Definitions of a "Commercially available off-the-shelf (COTS)" item and 41 U.S.C. Sec. 431 Commercially available off-the-shelf item acquisitions. If the construction material fits within the definition, then the requirements of the Buy American Act component test to define a domestic end product found at FAR Subpart 25.101, is waived and not applicable.
In other words, the contracting officer is required to insure the construction material is manufactured in the United States, but is not required to insure the cost of its domestic components exceeds 50 percent of the cost of all the components. If the item meets Buy American Act requirements as provided by the supplier in accordance with FAR provision at 52.225-10 Notice of Buy American Act Requirement—Construction Materials and subsequent clause at 52.225-9 Buy American Act—Construction Materials, no further investigation by the contracting officer is required.