S.J. Amoroso Construction Co., Inc. (Amo-roso) appeals the summary judgment of the United States Claims Court,1 S.J. Amoroso Construction Co. v. United States, 26 Cl.Ct. 759 (1992), denying Amoroso’s claim for additional compensation under a contract with the Army Corps of Engineers (Corps). We affirm.
I.
The facts underlying this appeal are set forth more completely in the opinion of the Claims Court, 26 Cl.Ct. 759, and a familiarity with that opinion is presumed. On August 17, 1987, the Corps and Amoroso entered into a $10,786,274.20 contract for the construction of a commissary' building at the Presidio, San Francisco, California. The contract was subject to the requirements of the Buy American Act (BAA), 41 U.S.C. §§ 10a-10d (1982), and corresponding Federal Acquisition Regulations (FAR), see 48 C.F.R. §§ 52.225-1 to -14 (1986). Instead of using the FAR clause for construction contracts,- 48 C.F.R. § 52.225-5 (hereafter clause 34), however, the contract included the FAR clause pertaining to nonappropriated fund supply contracts, 48 C.F.R. § 52.225-3 (hereafter clause 79). Amoroso does not dispute that the contract in this case is a construction contract;
Amoroso subcontracted with Bostrom-Bergen Metal Products (Bostrom) on September 25, 1987, for structural steel, miscellaneous steel, structural welding, ultrasonic inspection of welds and steel joists. After Bostrom informed Amoroso that it intended to purchase material from a foreign mill, Amoroso notified Bostrom by letter dated December 28,1987 that its “products are not preassembled, therefore each item that is *1074delivered to the site must be American made.” Amoroso enclosed with the letter a Corps compliance memorandum entitled “Updated Guidance on Buy American Act,” dated December 9, 1982, which, inter alia> provided:
4. ... construction materials means articles, materials and supplies brought to the site for incorporation in the building ■ or work. Components means articles, materials and supplies directly incorporated in construction materials.
5. Where the construction material has only one part it becomes synonymous with component. A Japanese beam is made of one component, hence the beam is 100% Japanese. Since the beam must be 50 + % ‘domestic’ (or excluded) components, it is rejected.
In January 1988, Amoroso requested that Bostrom confirm in writing its compliance with the BAA. Bostrom responded in a January 21, 1988 letter in which it set out the total cost for foreign steel purchased as $70,-882.60 and the total cost of “domestic product” as $101,767.64. The actual cost figures for “domestic product” apparently were adjusted downward because Amoroso thereafter informed the Corps that foreign steel costs were $70,000.00 and that domestic costs were $88,820, comprising the following:
DOMESTIC — LABOR & MATERIAL Cost to detail & cut raw material into specified lengths (beams) $ 8,000
Cost to install domestic material (connectors, angles, etc.) to the beams. Labor & material $52,470
Cost to apply domestic material (protective coating) to the beams. Labor & Material $28,350
$88,820
The cost figures furnished to the Corps represented the aggregate costs associated with all steel beams to be delivered to the site by Bostrom.
In a letter dated February 10, 1988, the Corps advised Amoroso that each beam must be considered “separately and singularly” in determining compliance with the BAA requirements and that costs of “[ojperations done on the foreign steel, such as drilling and cutting, do not result in its being combined with domestic materials and are not considered to alter the imported component percentage.” Bostrom thereafter performed individual computations for the approximately 1,000 steel pieces required under the contract. Only about two-thirds of them were found to comply with the Corps’s interpretation of the BAA requirement.
On December 27,1988, Amoroso submitted a certified claim on behalf of Bostrom to the Contracting Officer (CO), asserting that it was proper to consider the entire group of steel pieces for determining compliance with the BAA, and that the Corps incorrectly required each piece of steel delivered to the construction site to comply with the BAA Amoroso sought $863,250.00 for the costs incurred in testing the steel pieces .and replacing the ones that under the Corps’s interpretation did not satisfy the BAA requirements. The CO denied Amoroso’s claim in a final decision issued November 21, 1990. The Claims Court affirmed the CO’s final decision by granting the government’s motion for summary judgment and denying the cross-motion of Amoroso. This appeal followed.
II.
A. Amoroso argues that the Claims Court erred in construing the contract to include by operation of law clause 34 (the BAA clause required by FAR § 52.225-5 to be used in construction contracts) in lieu of clause 79. It contends that there is no strong federal procurement policy that requires clause 34 to be used. Amoroso also argues that even if clause 34, rather than clause 79, is held applicable, it should nonetheless be entitled to aggregate the costs of the steel beams delivered to the construction site in determining compliance with the BAA. Finally, Amoroso contends that the Claims Court erred in holding that cost of labor and transportation to the site cannot be included in the domestic *1075costs of the steel beams in measuring compli-ance with the BAA.2
B. The Claims Court construed the contract to include clause 34 for construction contracts under the authority of G.L. Christian & Associates v. United States, 312 F.2d 418, aff'd on reh’g, 320 F.2d 345, 160 Ct.Cl. 58 (1963). Under the so-called Christian doctrine, a mandatory contract clause that expresses a significant or deeply ingrained strand of public procurement policy is considered to be included in a contract by operation of law. General Eng’g & Mach. Works v. O’Keefe, 991 F.2d 775, 779 (Fed.Cir.1993); G.L. Christian, 312 F.2d at 424, 427; see also SCM Corp. v. United States, 645 F.2d 893, 903-04, 227 Ct.Cl. 12 (1981); Chris Berg, Inc. v. United States, 426 F.2d 314, 317, 192 Ct.Cl. 176 (1970).
As an initial matter, Amoroso contends that the Christian case is inapplicable because in that ease a clause was inadvertently omitted whereas in this case cláuse 79 was intentionally substituted for clause 34.3 This distinction, as the Claims Court held, is irrelevant. Application of the Christian doctrine turns not on whether the clause was intentionally or inadvertently omitted, but on whether procurement policies are being “avoided or evaded (deliberately or negligently) by lesser officials.” G.L. Christian & Assoc., 320 F.2d at 351. The Christian doctrine “guard[s] the dominant legislative policy against ad hoc encroachment or dispensation by the executive” and prevents “hobbl[ing] the very policies which the appointed rule-makers consider significant enough to call for ... mandatory regulation.” Id.; see also General Eng’g, 991 F.2d at 779. Moreover, the Christian doctrine echoes Supreme Court law that the United States is neither bound nor estopped by its agents who act beyond their authority or contrary to statute and regulations. See Federal Crop Ins. Corp. v. Merrill, 332 U.S. 380, 384, 68 S.Ct. 1, 3, 92 L.Ed. 10 (1947); see also Yosemite Park & Curry Co. v. United States, 582 F.2d 552, 558, 217 Ct.Cl. 360 (1978); Porter v. United States, 496 F.2d 583, 590, 204 Ct.Cl. 355 (1974).
Amoroso’s principal argument is that there is no significant or deeply ingrained strand of public procurement policy -requiring the inclusion of the correct BAA clause— clause 34 rather than clause 79 — in this contract. We disagree.'4 The BAA, first enacted in 1933, has long required in express terms that every construction contract for public buildings and works “shall contain a provision that in the performance of the work” only American materials will be used. 41 U.S.C. § 10b. Section 10b reads in pertinent part:
(a) Every contract for the construction, alteration, or repair of any public building or public work in the United States growing out of an appropriation heretofore made or hereafter to be made shall contain a provision that in the performance of the work the contractor, subcontractors, material men, or suppliers, shall use oniy such un-manufactured articles, materials, and supplies as have been mined or produced in the United States, and only such manufactured articles, materials, and supplies as have been manufactured in the United States substantially all from articles, materials, or supplies mined, produced, or manufactured, as the case may be, in the Unit*1076ed States except as provided in section 10a of this title: Provided, however, That if the head of the department or independent establishment making the contract shall find that in respect to some particular articles, materials, or supplies it is impracticable to make such requirement or that it would unreasonably increase the cost, an exception shall be noted in the specifications as to that particular article, material, or supply, and a public record made of the findings which justified the exception.
41 U.S.C. § 10b. Moreover, since its enactment 1 the BAA has distinguished between contracts for public works (construction contracts) and materials required for public use (supply contracts). Compare 41 U.S.C. § 10b (entitled “Contracts for public works; specification for use of American Materials; blacklisting contractors violating requirements”) with 41 U.S.C. § 10a (entitled “American materials required for public use”). The statute alone, therefore, evidences a significant and deeply ingrained strand of public procurement policy sufficient to require incorporation of the clause prescribed for construction contracts (clause 34) as a matter of law.
In addition, the procurement regulations themselves have reflected this significant, statutory policy for over 25 years. The FAR, promulgated in 1983, requires that “[t]he Contracting Officer shall insert the clause at 52.225-5, [clause 34], Buy American Act — Construction Materials, in solicitations and contracts for construction inside the United States.” 48 C.F.R. § 25.205 (1983). The procurement regulations that preceded the FAR — the Armed Services Procurement Regulations (ASPR) and the Federal Procurement Regulations (FPR) — similarly required in express terms that every construction contract include a Buy American Act clause, which in each case was in substance the same as the FAR required clause 34. See 32 C.F.R. § 18.509-5 (1969) (ASPR);5 41 C.F.R. § 1-18.605 (1969) (FPR).6
Moreover, even though the contract contains clause 79 for supply contracts, Amoroso should have realized that this clause was included in error and had a duty to inquire. See Newsom v. United States, 676 F.2d 647, 649, 230 Ct.Cl. 301 (1982); WPG Enter., Inc. v. United States, 323 F.2d 874, 877, 163 Ct.Cl. 1 (1963) (where there is an obvious omission the contractor has a duty to inquire). The parties do not dispute that this is a construction contract, yet the language in clause 79 does not apply to construction contracts. Clause 79 refers to “end products” and their availability in “commercial quantities.” 48 C.F.R. § 52.225-3.7 These terms are not consistent with and do not apply to a constructed building. Clause 34, which is in the contract document, albeit stricken, is entitled “BUY AMERICAN ACT CONSTRUCTION MATERIALS.” The stricken clause 34 refers to subpart 25.2 of the FAR which contains the sections requiring the inclusion of clause 34 in every domestic construction contract. See 48 C.F.R. § 52.225-5.8
*1077Finally, the Claims Court’s holding that clause 34, instead of clause 79, is the appropriate and controlling provision of this construction contract accords with , actions of the parties during performance of-the contract. See Sperry Corp. v. United States, 845 F.2d 965, 970 (Fed.Cir.1988) (citing General Warehouse Two, Inc. v. United States, 389 F.2d 1016, 1020, 181 Ct.Cl. 180 (1967)). During performance, the parties were on notice that the construction contract clause applied. The Corps explicitly advised Amoroso that only “domestic construction materials,” a term taken from clause 34, may be used and provided Amoroso with a BAA compliance memorandum explaining that all construction materials delivered to the sité must be domestic. In correspondence between Amoro-so and Bostrom, Amoroso iterated the Corps’s interpretation. Amoroso referred to the structural steel pieces fabricated by Bos-trom as “construction materials” consistent with the language in clause 34 and. provided Bostrom with the BAA compliance memorandum. It also forewarned Bostrom, paraphrasing the terminology contained in clause 34, that “each item that is delivered to the site must be American made.”
For the foregoing reasons the Claims Court property treated clause 34 as being a requirement of the instant contract. Our controlling precedent, see South Corp. v. United States, 690 F.2d 1368 (Fed.Cir.1982) (in banc) (Court of Claims decisions are binding precedent unless and until overruled by the Federal Circuit sitting in banc), so requires. ’ See G.L. Christian & Assoc., 312 F.2d at 424, 427; SCM Corp., 645 F.2d at 903-04; Chris Berg, Inc., 426 F.2d at 317.
C. We also are convinced that the Claims Court correctly interpreted and applied clause 34. The purpose of that clause is to ensure compliance with the BAA’s statutory mandate that only domestic construction materials be used in public construction contracts in the United States. See John C. Grimberg Co. v. United States, 869 F.2d 1475 (Fed.Cir.1989); John T. Brady & Co. v. United States, 693 F.2d 1380 (Fed.Cir.1982). The only exception permitted to the BAA requirement is when an agency head, after a timely application for waiver, determines that use of only domestic construction materials would be inconsistent with the public interest or that their cost is unreasonable. See 41 U.S.C. § lOd; Exec.Order No. 10,582, 3 C.F.R. § 230 (1958), reprinted in 41 U.S.C. § lOd app. at 1042 (1982). That exception is not here involved.
Clause 34 requires that the contract be performed with “domestic construction material” including “a construction material manufactured in the United States, if the cost of its components mined, produced, or manufactured .in the United .States exceeds 50 percent of the cost of all its components.” 48 C.F.R. § 52.225-5. “Construction materials” are those items “brought to the construction site for incorporation into the building.” Id. (emphasis added).
In its decision, the Claims Court noted that the Armed Services Board of Contract Appeals (ASBCA) in George Hyman Construction Co., ASBCA No. 13777, 69-2 BCA *1078(CCH) ¶ 7830 (1969), stated that when applying the requirements of clause 34, the “state of assembly or disassembly of items upon arrival at the site of incorporation may become determinative.” Subsequently, the ASBCA and the Comptroller General have regularly construed clause 34 to mean that if an item is delivered to the construction site unassembled, it is a separate item of construction material even though later combined with other items. Thus, each item of construction material brought to the site has been required to meet the BAA. See Ed Allen L. Bender, Inc., ASBCA No. 38068, 89-3 B.C.A. (CCH) ¶ 22,092 (1989); Ed Loshbaugh & Sons, Inc., ASBCA No. 36104, 88-3 B.C.A. (CCH) ¶. 21,023 (1988); Swanson Prod., Inc., ASBCA No. 33493, 87-1 B.C.A. (CCH) ¶ 19,661 (1987); 69 Comp.Gen. 211, 212 (1990); 51 Comp.Gen. 814, 818 (1972); 46 Comp.Gen. 813, 817 (1967). The Claims Court also noted that the ASBCA decision in Wright Contracting, Inc., ASBCA No. 39120, 91-1 BCA (CCH) ¶ 23,649 (1990), is almost identical factually to the present case. After considering many of the same arguments that are now made by Amoroso, the ASBCA concluded in Wright that each steel beam delivered to the site was required to comply with the BAA. Based on these interpretations, consistently followed by the ASBCA and the Comptroller General, the Claims Court concluded that each steel piece delivered to the construction site in this case must satisfy the requirements of the BAA.
The Claims Court’s interpretation of the required FAR provision, clause 34, is not only reasonable, but also required by the plain language of that clause. The clause defines a manufactured construction material in the singular, indicating that each item must be viewed separately for its domestic content. It would strain the plain meaning of clause 34 to interpret a group of steel pieces delivered to the construction site as “a construction material.” Moreover, construction materials are defined in clause 34 as items “brought to the construction site.” Such construction materials must therefore satisfy the BAA requirements at the time of delivery to the site, not at some later time when they may be incorporated or assembled into a larger item.9
D. Finally, Amoroso contends that the cost of labor and transportation to the job site may be included in determining percentages of domestic and foreign costs of the steel pieces under the BAA. This argument is contradicted directly by the language of clause 34. Clause 34 defines a “domestic construction material” that is manufactured in the United States as one in which the “cost of its components mined, produced, or manufactured in the United States exceeds 50 percent of the cost of all its components.” 48 C.F.R. § 52.225-5. “Components” are defined as “those articles, materials, and supplies incorporated directly into construction materials.” Because labor and transportation costs are not “articles, materials, [or] supplies,” and are not “incorporated directly into construction materials,” the Claims Court correctly held that Amoroso may not include them to determine percentages of domestic and foreign costs for purposes of the BAA.
CONCLUSION
For the foregoing reasons, the decision of the Claims Court is
AFFIRMED.
. The Claims Court was renamed the Court of Federal Claims on October 29, 1992. Federal Courts Administration Act of 1992, Pub.L. No. 102-572, § 902(a), .106 Stat. 4506, 4516.
. Although Amoroso argues that the cost of transportation should be included for measuring compliance with the BAA, it has not indicated, nor have we found in the record, the amount and nature of these transportation costs or whether they were presented to the CO.
. Although the Claims Court noted that evidence relating to the circumstances which led to the inclusion of clause 79 was not presented, the court indicated that all justifiable inferences should be drawn in non-movant Amoroso’s favor in deciding the government’s summary judgment motion. We also assume that the substitution of clause 79 for clause 34 was intentional.
.Because we hold that use of clause 34 in construction contracts is required by a clear and deeply ingrained public procurement policy, we consider Amoroso's reliance on Chamberlain Manufacturing Corp., ASBCA No. 18103, 74-1 BCA (CCH) II 10,368 (1973), to be unpersuasive. There the Armed Services Board of Contract Appeals held that the omission of the Government Property Clause in a contract, even though required by regulations, did not implicate strong procurement policy.
. The relevant ASPR section, 18.509-5, provided that "[t]he clause set forth below shall be inserted in all contracts for construction, except those executed on Standard Form 19 and DD Form 1155.”
. The relevant FPR section, 1-18.605, provided that "[e]xcept for contracts executed on Standard Form 19, contracts for affected construction shall include the following clause."
. Clause 79 of the contract reads in pertinent part:
79. BUY AMERICAN ACT
(a) In acquiring end products, the Buy American Act (41 U.S.Code lOa-d) is implemented by Executive Order 10582, 17 Dec 1954, provides that the fund give preference to domestic source end products. For the purpose of this clause:
(ii) "End products” means thqse articles, materials, and supplies, which are to be acquired under this contract for the public use; and
(b) The Contractor agrees that there will be delivered under this contract only domestic source end products, except end products:
(ii) Which the Government determines are not mined, produced, or manufactured in the United States in sufficient and reasonably a [sic] available commercial quantities and or a satisfactory, quality.... [Emphasis added.]
.The FAR-prescribed construction clause, which was included in the contract form, but marked out, reads in its entirety:
*107734. BUY AMERICAN ACT — CONSTRUCTION MATERIALS FAR 52.225-5
(a) The Buy American Act (41 U.S.C. 10) provides that the Government give preference to domestic construction material.
“Components,” as used in this clause, means those articles, materials, and supplies incorporated directly into construction materials.
"Construction materials,” as used in this clause, means articles, materials, and supplies brought to the construction site for incorporation into the building or work.
"Domestic construction material,” as used in this clause, means (1) an unmanufactured construction material mined or produced in the United States, or (2) a construction material manufactured in the United States, if the cost of its components mined, produced, or manufactured in the United States exceeds 50 percent of the cost of all its components. Components of foreign origin of the same class or kind as the construction materials determined to be unavailable pursuant to subparagraph 25.202(a)(3) of the Federal Acquisition Regulation (FAR) shall be treated as domestic.
(b) The Contractor agrees that only domestic construction material will be uséd by the Contractor, subcontractors, materialmen, and suppliers in the performance of this contract, except for foreign construction materials, if any, listed in this contract.
'(The foregoing requirements are administered in accordance with Executive Order No. 10582, dated December 17, 1954, as amended, and subpart 25.2 of the FAR).
. Treating a construction material delivered to the site as merely a component of a larger unit thereafter constructed would entail a difficult analysis and decision. Amoroso contends that the larger unit in this case for assessing BAA compliance should be the group of pieces making up the steel skeleton of the building. In another case, however, it might be argued that the building skeleton plus walls and roof should be the proper unit to use.
. On that point this case is distinguishable from the problem faced by Rembrant (sic), the painter, *1079who I thought should not have had to paint the walls to the letter of the contract rather than the requirements of the building. Wright Construction Co. Through Rembrant, Inc. v. United States, 919 F.2d 1569 (Fed.Cir.1990) (Plager, J., dissenting).