The issue certified to this court is whether, “[a]bsent a showing of changed circumstances, the doctrine of res judicata is applicable to decisions of a *381board of zoning appeals denying a request for a variance, even when the subsequent action seeks a zoning certificate based on the property’s alleged status as a prior legal nonconforming use as provided for in a zoning'resolution.” We answer this query in the affirmative.
In Set Products, Inc. v. Bainbridge Twp. Bd. of Zoning Appeals (1987), 31 Ohio St.3d 260, 31 OBR 463, 510 N.E.2d 373, paragraph one of the syllabus, this court held that “[t]he doctrine of res judicata applies to the decisions of a township board of zoning appeals relating to the grant or denial of variances * * We explained that res judicata, whether claim preclusion or issue preclusion, applies to administrative proceedings that are “ ‘of a judicial nature and where the parties have had an ample opportunity to litigate the issues involved in the proceeding.’ ” Id. at 263, 31 OBR at 465, 510 N.E.2d at 376 (quoting Superior’s Brand v. Lindley [1980], 62 Ohio St.2d 133, 16 O.O.3d 150, 403 N.E.2d 996, syllabus). See, also, Consumers’ Counsel v. Pub. Util. Comm. (1985), 16 Ohio St.3d 9, 16 OBR 361, 475 N.E.2d 782.
The doctrine of res judicata involves both claim preclusion (historically called estoppel by judgment in Ohio) and issue preclusion (traditionally known as collateral estoppel). See Whitehead v. Gen. Tel. Co. (1969), 20 Ohio St.2d 108, 49 O.O.2d 435, 254 N.E.2d 10; Krahn v. Kinney (1989), 43 Ohio St.3d 103, 107, 538 N.E.2d 1058, 1062; 46 American Jurisprudence 2d (1994) 780, Judgments, Section 516. This case involves claim preclusion only.
With regard to the claim-preclusive effect of the doctrine of res judicata, this court, in previous years, has stated: “A final judgment or decree rendered upon the merits, without fraud or collusion, by a court of competent jurisdiction * * * is a complete bar to any subsequent action on the same claim or cause of action between the parties or those in privity with them.” Norwood v. McDonald (1943), 142 Ohio St. 299, 27 O.O. 240, 52 N.E.2d 67, paragraph one of the syllabus; see, also, Whitehead v. Gen. Tel. Co., supra, paragraph one of the syllabus. We also have stated: “A judgment or decree in a former action does not bar a subsequent action where the causes of action are not the same, even though each action relates to the same subject matter.” Norwood, supra, paragraph two of the syllabus; see, also, Whitehead, supra, paragraph two of the syllabus. To determine whether a second action was barred by this rule of law, one of the primary considerations was the identity of the evidence necessary to sustain each action. See Norwood, supra, paragraph four of the syllabus.
Relying primarily on Whitehead, supra, Grava asserts that the doctrine of res judicata does not bar the present action concerning his second application for a zoning certificate because this action involves a distinctly different method of obtaining relief than the previous action involving his first application. He *382argues that the facts necessary to obtain relief under Section 906.0 are different from the facts necessary to obtain a variance.2
In recent years, this court has not limited the application of the doctrine of res judicata to bar only those subsequent actions involving the same legal theory of recovery as a previous action. In Natl. Amusements, Inc. v. Springdale (1990), 53 Ohio St.3d 60, 62, 558 N.E.2d 1178, 1180, we stated: “It has long been the law of Ohio that ‘an existing final judgment or decree between the parties to litigation is conclusive as to all claims which were or might have been litigated in a first lawsuit’ ” (emphasis sic) (quoting Rogers v. Whitehall [1986], 25 Ohio St.3d 67, 69, 25 OBR 89, 90, 494 N.E.2d 1387, 1388). We also declared that “[t]he doctrine of res judicata requires a plaintiff to present every ground for relief in the first action, or be forever barred from asserting it.” Id.
Today, we expressly adhere to the modern application of the doctrine of res judicata, as stated in 1 Restatement of the Law 2d, Judgments (1982), Sections 24-25, and hold that a valid, final judgment rendered upon the merits bars all subsequent actions based upon any claim arising out of the transaction or occurrence that was the subject matter of the previous action. Therefore, we overrule the second paragraph of the syllabus in Norwood, supra, and overrule the second paragraph of the syllabus in Whitehead, supra, to the extent it is inconsistent with today’s holding.
Section 24(1) of the Restatement of Judgments, supra, at 196, provides: “When a valid and final judgment rendered in an action extinguishes the plaintiffs claim pursuant to the rules of merger or bar * * *, the claim extinguished includes all rights of the plaintiff to remedies against the defendant with respect to all or any part of the transaction, or series of connected transactions, out of which the action arose.” See, also, 46 American Jurisprudence 2d, supra, at Sections 516 and 533. Comment b to Section 24 of the Restatement of Judgments, supra, at 198-199, defines a “transaction” as a “common nucleus of operative facts.” Comment c to Section 24, at 200, plainly states: “That a number of different legal theories casting liability on an actor may apply to a given episode does not create multiple transactions and hence multiple claims. This remains true although the several legal theories depend on different shadings of the facts, or would *383emphasize different elements of the facts, or would call for different measures of liability or different kinds of relief.”
Section 25 of the Restatement of Judgments, supra, at 209, further explains: “The rule of § 24 applies to extinguish a claim by the plaintiff against the defendant even though the plaintiff is prepared in the second action (1) To present evidence or grounds or theories of the case not presented in the first action, or (2) To seek remedies or forms of relief not demanded in the first action.” (Emphasis added.) See, also, 46 American Jurisprudence 2d, supra, at Sections 535 and 537. The rationale for such a rule is aptly stated in Comment a to Section 24 of the Restatement of Judgments, supra, at 196-197: “[I]n the days when civil procedure still bore the imprint of the forms of action and the division between law and equity, the courts were prone to associate claim with a single theory of recovery, so that, with respect to one transaction, a plaintiff might have as many claims as there were theories of the substantive law upon which he could seek relief against the defendant. Thus, defeated in an action based on one theory, the plaintiff might be able to maintain another action based on a different theory, even though both actions were grounded upon the defendant’s identical act or connected acts forming a single life-situation. * * * The present trend is to see claim in factual terms and to make it coterminous with the transaction regardless of the number of substantive theories, or variant forms of relief flowing from those theories, that may be available to the plaintiff * * *; regardless of the variations in the evidence needed to support the theories or rights.” (Emphasis added.)
We hold that Grava’s second application for a zoning certificate is barred by the doctrine of res judicata. Grava’s second application is based on a claim arising from a nucleus of facts that was the subject matter of his first application. In both instances, Grava was attempting to construct exactly the same building on the same tract of land, which had fewer acres than Section 404.4 of the local zoning ordinance required. In fact, the only difference between the two applications is the theory of substantive law under which Grava sought relief.
Grava argues that barring the present action would be unfair. However, he had a full and fair opportunity to present his case and obtain a zoning certificate during the proceedings involving his first application and did not appeal the zoning board’s denial of his request. Grava simply failed to avail himself of all available grounds for relief in the first proceeding. Absent changed circumstances, refusing to allow Grava to use an alternate legal theory overlooked in the previous proceedings does not work an injustice. Instead, by providing parties with an incentive to resolve conclusively an entire controversy involving the same core of facts, such refusal establishes certainty in legal relations and individual rights, accords stability to judgments, and promotes the efficient use of limited *384judicial or quasi-judicial time and resources. The instability that would follow the establishment of a precedent for disregarding the doctrine of res judicata for “equitable” reasons would be greater than the benefit that might result from relieving some cases of individual hardship.
For the foregoing reasons, we affirm the judgment of the court of appeals.
Judgment affirmed.
Moyer, C.J., F.E. Sweeney and Cook, JJ., concur. Douglas, Resnick and Pfeifer, JJ., dissent.. For example, in order to establish the right to an area variance, an owner must show that he has encountered “practical difficulties” in the use of his property. See Duncan v. Middlefield (1986), 23 Ohio St.3d 83, 23 OBR 212, 491 N.E.2d 692. On the other hand, in order for an owner to obtain nonconforming-use status, in accordance with Section 906.0, the owner must prove that (1) he had a “lot of record” prior to the effective date of the regulation or any of its restrictive amendments, (2) the property consists of at least 1.5 acres and has a minimum of one hundred feet of frontage, and (3) all other zoning requirements for the zoning district have been met.