The appellant board revoked the license of respondent as a professional engineer pur*632suant to the statute making any “gross negligence, incompetency or misconduct” grounds for such revocation.1
The scope of circuit court review of such board determination is prescribed by statute.2 This court’s scope of review is the same.3 The issue in this case is whether there is substantial evidence,4 not to be equated with preponderance of evidence,5 that supports the board’s find*633ings, with due weight to be given, to the experience, technical competence, and specialized knowledge of the board.6 Neither this court nor the circuit court is to retry the case, substituting the court’s judgment for that of the board.7 Applying this statutorily mandated standard, we will review (1) the findings of fact, and (2) the conclusions of law that undergird the board’s revocation of respondent’s license.
Findings of fact.
The board found that the respondent was employed to prepare plans and specifications for and to supervise construction of a garage addition. It found that the respondent did prepare such plans and specifications and was responsible for the construction of said garage addition. It found that a portion of the addition constructed collapsed, and that the collapse was caused by the failure of an “open web frame truss,” designed by respondent. As to gross negligence, incompetency or misconduct, the board made two material findings of fact: (1) That the said truss was not designed or constructed to support a *634reasonable live load. This is supported by substantial evidence.8 (2) That the respondent performed welding on the said garage addition without being certified as required by sec. ind 53.16 (13), 4 Wisconsin Administrative Code. This is conceded.9 It is upon these two findings of fact 10 that the board’s conclusions of law rest.
Conclusions of law.
The board reached three conclusions of law to support its concluding that it was in the public interest to revoke the certificate of registration as a professional engineer of the respondent. It found, (1) That respondent was incompetent; (2) that respondent was guilty of gross negligence; and (3) that the respondent was guilty of misconduct. Each conclusion will be separately reviewed.
1. Was respondent incompetent?
The board held that respondent’s “failure to design an ‘open web frame truss’ which would support a reasonable live load” constituted incompetency. The trial court *635set aside the board’s finding of incompetence for lack of evidence. Quoting Webster as defining incompetence to mean “without adequate ability, knowledge, fitness, etc.,” the trial court held as a matter of law that “a single instance of a failure to use ordinary care is not of itself incompetence,” with the qualification that “if it demonstrates a lack of ability to perform the professional functions it may be incompetence as that word is generally understood.” The trial court then struck the board finding of incompetence, holding: “There is no evidence from which one could infer any . . . lack of ability to make a proper design as would be said to be incompetence.”
We are required to negative any implication that it is only continued or repeated acts that can constitute incompetency in any situation. Where a real estate broker violated board rules in a single real estate transaction, this court upheld an agency finding of incompetency based upon conduct in a single situation.11 However, in the case before us, we agree with the trial court that the evidence does not establish incompetency. The statute involved makes incompetency or gross negligence or misconduct grounds for revocation of license.12 While we have upheld revocation where the three were lumped together as grounds for revocation,13 each has a distinct meaning. Incompetence does refer to some demonstrated *636lack of competence or ability to perform the professional functions. Gross negligence does involve some higher degree of a failure to exercise ordinary care of judgment in a given situation. Misconduct does relate to some deviation from a fixed duty or definite rule of conduct. The three words are not entirely synonymous nor completely interchangeable.
We deal here not with the board’s findings of fact, but with its conclusion of law that the facts found warrant concluding the respondent was incompetent, rather than negligent or grossly negligent, in failing to properly design the building addition.14 We have here an admitted error in the designing of the roof supports for a building addition. While the record is nearly devoid of testimony bearing upon how easy it would be to make or notice such error, the ILHR department engineer testified that the error was not obvious. In a letter to that department, the respondent stated, “This has been the first and only failure that I have experienced during the eleven years of private practice, and I can assure you, the last.” We are considering here what the board, in its conclusions of law, termed “failure to design an ‘open web frame truss’ which would support a reasonable live load.” We would hold, under these circumstances and on this record, that what the trial court referred to as “the acknowledged mistake of petitioner in the design resulting in the roof collapse under stress of a normal load” did not constitute incompetency. By a somewhat different route, we reach the same conclusion the trial *637court reached that the finding of incompetency by the board is unsupported by substantial evidence in view of the entire record as submitted.
2. Was respondent grossly negligent ?
In its opinion the trial court went further to hold: “. . . we do not think that evidence of a single failure to use ordinary care in design or failure to detect the error is either gross negligence or incompetence . . . While terming such single failure as “no more than an inadvertent error,” it is clear that the trial court considered the failure in design and supervision to be an act of ordinary negligence. It observed, “Had the legislature intended that ordinary negligence was to be a ground for revocation of a license, it would not have modified the negligence as gross.” As a matter of law then, the trial court is putting the negligent act here in the area of inadvertence or ordinary negligence and, as a matter of law, outside the realm of gross negligence. The trial court, in its opinion, stated that the evidence justified “no more than a finding of ordinary negligence.”
In holding gross negligence not applicable to the acts of respondent, the trial court cited and relied upon the Bielski Case 15 as implying a course of conduct, in the trial court’s words, “so reckless or in wanton disregard of the rights and safety of others as to evince a willingness to cause injury or damage.” But Bielski makes clear that, initially, the difference between ordinary and gross negligence was a matter of degree, not a difference in kind.16 The decision tells not only how, but why, gross negligence “acquired by metamorphosis a new nature” in tort, and particularly automobile accident *638cases.17 There is no reason for importing that judicial history and result into the term “gross negligence” in this statute governing revocation of engineers’ licenses. As here used, the term “gross negligence” refers to degree of negligence, exactly as the term traditionally did. Even as the term “unprofessional conduct” has a different meaning and application in various professions, so the term “gross negligence,” applied to an architect or professional engineer, distinguishes between gross or grave acts of negligence as compared to less serious or more ordinary acts of negligence. The legislative' command that due weight is to be given to “the experience, technical competence, and specialized knowledge of the agency involved,” 18 in determining what is gross negligence, indicates the determination of the grossness of the negligence is to be made by those knowledgeable as to the particular profession involved.
While properly included in a conclusion of law, we see the determination of whether admitted negligence is of such a degree as to constitute gross negligence as essentially a fact-finding process. Certainly it is a determination in which experience, technical competence and specialized knowledge are required, where the finding *639concerns the degree of negligence in a failure to act of a professional man in a licensed and specialized profession. A lay person would suspect that failure to properly design or construct a roof is more serious than the failure to properly design and build a doorjamb or windowsill. But such lay person might consider the slightest oversight to be gross negligence if it were causally connected to the collapse of a church or school gymnasium roof on the night of its public dedication program. Experience, competence and specialized knowledge of the profession and its standards are certainly helpful in determining whether a failure to exercise care was grossly negligent.
Holding that the determination of whether the failure to properly design or supervise the construction of the roof supporting truss was or was not gross negligence is a matter for the board to determine, subject to the scope of judicial review, we here would remand the case to the examining board to make such determination.
It is true that the appellant board found the respondent guilty of gross negligence, but it did so stating that “the failure to correct said design prior to construction constituted gross negligence.” This cannot be read as a generalized reference to the fact that the respondent supervised the construction and thereby had additional opportunities to notice and correct the defect in the plans and specifications. Briefs and arguments make clear that the holding is that the respondent failed to correct his plans and calculations after being warned or notified by state engineers of probable defects. On this point the trial court opinion stated: “. . . Petitioner was led astray by some erroneous calculations which apparently were not so obvious as to invite the express disapproval of the Commission’s examiners of the plans, although there is a rather cryptic handwritten note in the record which the Board apparently construed as a criticism or inquiry.,. . .” The “rather cryptic” note is a penciled notation on a letter that began “A question developed *640on stresses . . .” and ended with “This also checked out.” We hold both note and notation too vague and unclear to constitute notice of possible defect, much less warning of actual defect, in the plans and specifications. There was testimony concerning a conversation of respondent with a state assistant chief engineer who did not take the stand as a witness. The hearsay version of that conversation had it ending with the state engineer being “satisfied.” While it is true that respondent failed to correct the plans and specifications while he was supervising the construction, there is no evidence in this record to sustain a finding that he was warned or told of the defect by state representatives. There is no finding of fact that he was so warned or put on notice. On remand, the sole question as to gross negligence is to be whether the failure to design and construct an “open web frame truss” which would support a reasonable live load constituted gross negligence.
3. Was respondent guilty of misconduct?
The board found that “performing welding for a project being constructed under his supervision, without being certified as required by Section ind 53.16 (13), Wis. Adm. Code, constituted misconduct in the practice of Professional Engineering by the respondent.” Respondent does not deny that he did welding on the project involved, and that he is not a certified welder. Professional engineers are required to abide by provisions of the state administrative code.19 That code covers welder qualifications,20 inspection requirements *641for welders,21 and certification of qualified welders.22 Respondent contends that welding does not come within the definition of professional engineering, as statutorily defined. However, the statute provides that “responsible supervision of construction” is part of the practice of professional engineering.23 The welding done by him as supervising engineer on the building project falls within the scope of “responsible supervision” of the construction project.24 His welding work was done in the practice of professional engineering. The trial court held that “the petitioner doing welding for the job *642without being certified was an intentional act knowingly done in violation of a known administrative rule which has the force of law,” and that the finding of misconduct is here supported by substantial evidence. We agree.
Finally, respondent argues that the statute providing for revocation of license for misconduct is unconstitutionally vague. The statute refers to “misconduct in the practice of . . . professional engineering as a registered professional engineer.” The word “misconduct” has a broad scope, and a wide range of meaning “according to the different connections in which it is used.” 25 As used in this statute it clearly relates to unprofessional acts, and is synonymous with “unprofessional conduct,” conduct that violates those standards of professional behavior which through professional experience have become established.26 We do not find this statute, on its face, to be unconstitutionally vague. As applied to *643respondent, there is no shadow of right to claim vagueness. The respondent concedes a deliberate violation of a provision of the administrative code and that code requires licensed professional engineers to “abide by, and conform to, the provisions of the Wisconsin Administrative Code and all local codes and ordinances.” 27 Given the specificity of this charge and the finding of fact and conclusion of law as to the welding work, we see no basis for claim of vagueness as applied to respondent. The trial court in its opinion, stated: “. . . We believe the standards for revocation are sufficiently definite so that members of the profession should have no trouble staying within the bounds of propriety.” We agree, and hold the finding of misconduct based on respondent’s doing the welding work to be supported by substantial evidence.
The trial court remanded this case to the examining board to impose a penalty on respondent, if it chose to do so, upon the board determination, upheld by the circuit court, that respondent was guilty of misconduct for his violation of ind 53.16 (13), 4 Wisconsin Administrative Code. We enlarge the nature of the remand to add that the examining board determine whether the respondent’s *644failure to design and supervise the construction of an “open web frame truss” which would support a reasonable live load constituted gross negligence. If the board determines such failure to design and supervise to constitute gross negligence, it shall impose a penalty appropriate to its finding of gross negligence and misconduct. If the board determines such failure to design and supervise to have been an act of ordinary negligence, it shall impose a penalty appropriate to its finding of an act of misconduct as to the welding.
By the Court. — Judgment appealed from is modified to expand the nature of remand to the board to include a determination of whether respondent’s design error constituted gross negligence and, as modified, affirmed.