Is this conflicting information? Can you reference both commercial and construction requirements and clauses in one solicitation/award?
You can use mix commercial and construction clauses in one contract. FAR 36.101(c) states:
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(c) A contract for both construction and supplies or services shall include --
(1) Clauses applicable to the predominant part of the work (see Subpart 22.4), or
(2) If the contract is divided into parts, the clauses applicable to each portion.
If the contracting officer determines that the installation of the doors and the cost of the doors are separate and distinct, it would be appropriate at apply construction clauses to the installation part and commercial clauses to the supply items (doors). The construction portion of the work should be "substantial" (even if not the majority of the work) for FAR Part 36 elements to apply. I suspect that the labor to install the doors will in fact be a substantial part of the overall effort.