(dissenting). This is not a complicated case. The issue is whether sec. 145.06, Stats.,1 applies to the installation of plumbing products in manufactured buildings. The Manufactured Building Code does not address this issue.
Since at least 1975, the department has not applied sec. 145.06, Stats., to manufactured housing. Instead, the department reviewed and approved plumbing plans for manufactured buildings on a "product approval" basis. To obtain "product approval," a company submitted specifications for a prefabricated or manufactured building containing plumbing. Once approved, the building could be sold in this state.
The legislature has concluded that to protect the safety of Wisconsin residents, plumbing must be installed under the supervision of persons who have had extensive training in the proper installation of plumbing equipment — Wisconsin licensed master plumbers. See sec. 145.06(2), Stats. The legislature has also enacted a Manufactured Building Code which, except for a provi*996sion which recognizes the continued validity of ch. 145, Stats., does not mention this requirement. See secs. 101.70 to 101.77, Stats. Although the majority examines voluminous task force and advisory commission reports, it finds nothing specifically indicating that master plumbers are not required to supervise in-plant manufactured housing projects.
Given a specific statutory requirement, and other legislation which addresses a different subject, a court would usually conclude that the legislature, aware of the master plumber requirement of sec. 145.06(2), Stats., chose not to exempt manufactured housing from that requirement. See Maxey v. Redevelopment Auth. of Racine, 120 Wis. 2d 13, 24, 353 N.W.2d 812, 818 (Ct. App. 1984) (when legislature enacts a statute, it does so with full knowledge of existing statutes). It is the duty of the courts to construe two statutes so that both will be operative. Repeal of a statute by implication is disfavored. Id.
Rather than focus on whether sec. 145.06, Stats, is ambiguous and, if not, whether there is any reason to ignore its plain meaning, the majority instead subdivides the issues as follows: (1) "whether the department has correctly construed its administrative rules," and (2) "whether the Manufactured Building Code authorized the department to adopt its administrative rules which it has interpreted as permitting it to approve, for sale and installation in the state, manufactured housing in which the plumbing has been installed without complying with sec. 145.06(l)(a) and (2), Stats." Majority op. at 976.
The subject of this lawsuit is the interpretation of sec. 145.06, Stats. I fail to see the relevancy of whether the department has correctly interpreted its own administrative regulations. Pfeiffer v. Board of Regents, 110 Wis. 2d 146, 328 N.W.2d 279 (1983), holds that we *997should give controlling weight to "the interpretation by an administrative agency of its own regulation." Id. at 154, 328 N.W.2d at 283 (citation omitted). However, as a footnote to Pfeiffer emphasizes, this standard applies "[w]hen the construction of an administrative regulation rather than a statute is in issue." Id. at 155 n.12, 328 N.W.2d at 283 n.12 (emphasis added) (quoting Udall v. Tollman, 380 U.S. 1, 16 (1965)).2 The controversy in this case involves whether the department has erroneously interpreted sec. 145.06, Stats., not whether this interpretation complies with the numerous administrative code provisions cited by the majority. The latter inquiry is irrelevant.
The department's interpretation of sec. 145.06, Stats., the majority urges, is entitled to the "highest level of deference courts give to agency interpretations of statutes." Majority op. at 986 (citation omitted). This is because this case presents "the unique circumstance that the department's expertise and experience contributed to the formulation of the legislation [the Manufactured Building Code] which it subsequently was required to interpret." Majority op. at 984.
The majority cites no Wisconsin cases for the proposition that an agency's construction of a statute warrants nearly conclusive deference where the agency participates in the drafting of a statute. The department's involvement in pending legislation affecting the department is not unique. Most agencies do the same thing.
*998Agency participation means only that the agency considered the matters contained in the legislation. The agency may or may not have considered collateral matters. Inferences drawn in those situations are guesswork. Regardless, the statute involved in this case is not the Manufactured Building Code (secs. 101.70 to 101.77, Stats.), but sec. 145.06, Stats. Indeed, the parties' original briefs in this case did not mention the Manufactured Building Code. Only when this court ordered briefing on the Code did the parties address it. The fact that the department was extensively involved in the formulation of the Manufactured Building Code and the administrative rules implementing the Code confers upon it no special expertise to construe a statute that has nothing to do with the Manufactured Building Code.
The majority also ignores a part of the Manufactured Building Code which indicates that the legislature was aware of chapter 145's existence, and required the department to enact rules which assured compliance with chapter 145. Section 101.73, Stats., provides in pertinent part:
The department shall:
(2) Adopt rules for the examination of plans and specifications and for periodic in-plant and on-site inspections of manufacturing facilities, processes, fabrication, assembly and installation of manufactured buildings to ensure that examinations and inspections are made in compliance with the rules ... for indoor plumbing adopted by the department under ch. 145. [Emphasis added.]
One of the rules for indoor plumbing adopted by the department under chapter 145 is Wis. Adm. Code sec. ILHR 82.40(9):
*999PIPING BY PLUMBER. In accordance with ch. 145, Stats., piping which conveys water for human use or consumption, or to plumbing fixtures and plumbing appliances of every description, shall be installed by persons licensed by the department.
Had the legislature intended that the Manufactured Building Code's insignia plan supplant sec. 145.06(2), Stats., it would not have required the department to adopt rules that mandate the use of master plumbers to install water pipes. And certainly, the legislature would not have included this requirement in the Manufactured Building Code.
The effect of the majority's decision is to substitute the department's "compliance assurance program" in place of licensed plumber supervision, and to substitute its view of the need for licensed plumbers for a contrary legislative determination. The "compliance assurance program," however, is concerned with design, not fabrication integrity. The best plans, specifications and calculations can be rendered unsafe by an untrained assembly line worker. A "compliance assurance program" is merely a model document to evaluate, approve and inspect a manufactured building. See Wisconsin Adm. Code sec. ILHR 20.24(3).
Were I writing for the majority, I would conclude that the legislature's plainly demonstrated intent was that plumbing, in all dwellings, be installed under the supervision of Wisconsin licensed master plumbers.
Section 145.06, Stats., provides in part:
(1)(a) No person may engage in or work at plumbing in the state unless licensed to do so by the department. A master plumber may work as a journeyman. No person may act as a plumbing apprentice or pipe layer unless registered with the department.
(2) No person shall install plumbing unless at all times a licensed master plumber is in charge, who shall be responsible for proper installation. Licenses shall be issued only to individuals and no license shall be issued to or in the name of any firm or corporation. No such license shall be transferable. It is unlawful for any licensed master plumber to allow the use of his license, directly or indirectly, for the purpose of obtaining local permits for others or to allow the use of his license by others to install plumbing work. [Emphasis added.]
The Pfeiffer court continues:
An administrative agency knows the specific purposes of the regulations it has promulgated. Moreover, an agency has a certain expertise in the area it is called upon to regulate. Thus we believe that an agency is in the best position to interpret its own regulations in accordance with their underlying purposes.
Id. at 155, 328 N.W.2d at 283.