OPINION
EASTAUGH, Justice.
I. INTRODUCTION
James Pruitt applied to the City of Seward for a permit to erect a new building in the city's industrial zone. Pruitt's building plan included a canopy over the building's front entrance. The city refused to grant permission to build the canopy, claiming that the canopy was an "attachment to a building" that would extend into the building setback mandated by Seward's zoning code. Pruitt did not appeal. After Pruitt erected his building, including the canopy, the city filed a superior court enforcement action and argued that Pruitt could not defend in that action because he had not exhausted his administrative remedies. The superior court used its independent judgment to interpret the city's zoning codes, held that Pruitt was in violation of the zoning codes, and ordered him to remove the canopy. We hold that, because the city did not provide him with notice that its interpretation of the city zoning code was a final action, the exhaustion doctrine does not foreclose Pruitt from defending the city's enforcement action. We also hold that, because the city effectively denied Pruitt an opportunity to appeal its zoning decision and because the zoning code is ambiguous, the superior court should have given him an opportunity to submit the issue of the code's meaning to the city's planning and zoning commission. We therefore remand with instructions to hold the enforce[1133]*1133ment action in abeyance so Pruitt can appeal the city's interpretation of the zoning code.
II. FACTS AND PROCEEDINGS
A. Facts
James Pruitt applied to the City of Seward for a building permit in August 2000. Pruitt proposed erecting a pre-fabricated building in Seward's industrial zone. The building plan included a canopy over the front entrance of the building. The Seward City Code's (SCC) zoning provisions require that all "structures" in industrial zones be set back at least twenty feet from the street.1 Seward City Code § 15.10.140 defines "setback" as:
The required minimum distance from right-of-way or lot line that establishes the area within which only fencing, landscaping, driveways, parking and similar uses are permitted. Any structure including, but not limited to, decks, stairways, porches or other attachments to a building are specifically prohibited in the setback. Building eaves are permitted to extend into the setback a maximum of two feet.
Seward City Code § 15.10.140 defines "structure" as:
Anything constructed or erected on the ground or attached to something having location on the ground, including, but not limited to, buildings, towers, and sheds. Fences, retaining walls less than three feet in height, signs, and similar improvements of a minor character are excluded.
Linda-Rae Olsen, the city clerk, sent Pruitt a letter on August 18, 2000. It cited SCC § 15.10.140, and stated that from the building plans it appeared that the "roof [eave], the [fascia] panel, and the canopy over the store entrance" would extend into the setback. The letter indicated that Pruitt's site plan could not be approved unless he verified that:
1. The building [eaves] do not extend over two feet into the 20 foot front yard setback[;]
2. the store front canopy does not extend into the 20 foot front yard setback and;
8. the [fascia] panel does not extend into the 20 foot front yard or 10 foot side yard setbacks.
At Pruitt's request, Olsen later faxed him information on applying for a variance from the zoning code.
Pruitt's building permit was issued in October 2000. It contained the following statement in bold print: "The Canopy is not part of this permit [and] has not been approved."
The city engineer conducted inspections during construction and verbally notified Pruitt and his contractor during those inspections that the canopy extended into the setback. Dave Calvert, the city's building official, performed the final inspection. He told Pruitt that the canopy was in the setback and that he would not issue a certificate of occupancy until that problem was corrected.
Rachel James, Seward's city planner, sent Pruitt a letter in March 2001 notifying him that his canopy was "in violation of City Code § 15.10.140 pertaining to setbacks." The letter instructed Pruitt to remove the canopy from his building or provide an "as-built survey" showing that the canopy was not located in the setback. James also informed Pruitt that the planning and zoning commission ("commission") had put the topic of setbacks on its March 6, 2001 agenda.
Pruitt then filed a variance application requesting authorization to allow "a one to three foot doorway overhang (canopy) into the twenty foot front yard setback." A pub-lie hearing on the variance application was held in April 2001 and the commission denied the application. Pruitt did not appeal this denial.
Calvert sent Pruitt a letter in October 2001 notifying Pruitt that it was a violation of the Uniform Building Code to use or occupy the building without a certificate of occupancy. Calvert again emphasized that he would not issue a certificate of occupancy until the building complied with the city's zoning requirements. The letter also stated: "As always, you can appeal this decision to the City Council if you so desire."
[1134]*1134Pruitt occupied the property and opened the building for business without a certificate of occupancy. In March 2002 Pruitt talked to Calvert about building a loading dock on the back of his store and applied for a building permit Calvert told Pruitt that he would not issue any additional permits until Pruitt had corrected the "canopy setback problem" and obtained a certificate of occupancy for the building.
As James had suggested in March 2001, Pruitt obtained an as-built survey in September 2002 showing that his canopy extended into the setback by two feet. Pruitt then built a covered loading dock without a permit. - Calvert sent Pruitt a letter in May 2008 stating that by building the loading dock, Pruitt violated the building code because he did not submit plans for review or submit to inspections during the building process. Calvert reminded Pruitt that the canopy was still in the setback and that Pruitt did not have a certificate of occupancy for the building. Calvert also notified Pruitt that he could be fined up to $1,000 per day for the violations.
In a July 2003 letter Calvert threatened legal action and warned Pruitt that steps would be taken to fine him up to $1,000 per day if he did not correct his violations of the building code. Calvert instructed Pruitt to reduce his canopy width and to obtain a building permit, a plan review, and inspections for the loading dock. Calvert advised Pruitt that the city would close the threatened legal action if Pruitt complied.
During fall 2003 the commission addressed the setback requirement in the industrial zone at multiple commission meetings. In December 20038 the commission recommended reducing industrial setbacks to ten feet. Nothing in the record indicates whether the city council adopted the commission's recommendation and changed the city code.
B. Proceedings Below
The City of Seward filed a superior court enforcement action against Pruitt in November 2008. The city's complaint alleged that Pruitt: (1) violated SCC § 12.05.010 by using and occupying the building without a certificate of occupancy; (2) intentionally violated the building code by constructing the canopy in violation of the building permit; (8) violated the city's zoning code by constructing a canopy that extended into the required twenty foot setback; and (4) intentionally violated the building code by constructing a loading dock without a permit. The city asked the court to impose a fine of $1,000 per violation per day plus punitive damages, to require removal of the logding dock, and to enjoin Pruitt from using the building without a certificate of occupancy.
Pruitt counterclaimed, asserting that the city's treatment of the canopy as a violation of SCC § 15.10.140 violated his federal and state rights to due process and equal protection. Pruitt requested either an injunction prohibiting the city from classifying canopies such as Pruitt's as violations of SCC § 15.10.140 or a decree declaring that section 140 "does not prohibit the canopy on Pruitt's building or, if it does, that said ordinance is unconstitutional and may not be enforced against Pruitt."
The parties eross-moved for summary judgment and the superior court heard oral argument. The city claimed that Pruitt had waived his right to raise any objections or to make any claims against the city because he did not exhaust his administrative remedies under the zoning and building codes. The city noted that Pruitt had not appealed the commission's denial of his variance application. It also alleged that Pruitt should have administratively appealed the city's interpretation of SCC § 15.10.140 per SCC § 15.10.410.2
[1135]*1135The superior court held that resolution of the exhaustion issue was not necessary because:
Even if no deference is given to the Building Inspector's decision, the court reaches the conclusion that the canopy is an impermissible encroachment because the plain language of SCC 15.10.140 prevents an "attachment" to a "structure" to extend into the setback as far as the subject canopy. See: SCC 15.10.140. There is no question that the canopy is an attachment to a structure.
The superior court refused to allow Pruitt to challenge the causes of action arising out of the city's building code because it found that Pruitt was aware of "the right to appeal violations of the building code" and had failed to do so. The court also held that Pruitt's constitutional arguments were "without merit." As a sanction, the court gave Pruitt the option of either bringing his building into compliance with the zoning and building codes within sixty days or paying a fine of $10.00 per violation per day for the approximately four years since the initial violation. The court also declared the city the prevailing party and awarded it attorney's fees.
Pruitt appeals.
III. DISCUSSION
A. Pruitt Is Not Barred from Raising a Defense to the Enforcement Action.
The city argues that Pruitt cannot raise any objection or defense to its enforcement action because he failed to exhaust his administrative remedies. It claims that Pruitt was required to appeal the city's interpretation of the zoning code under the procedure set out in SCC § 15.10.410. That seetion allows a person aggrieved by any action or determination under chapter 15.10 of the city code to appeal that action or determination to the city's planning and zoning commission within ten days. It also specifies that any action not appealed within the pre-seribed time limit is final.3
The city also argues that Pruitt should have appealed the city's building code decisions through the administrative appeal process set out in SCC § 12.05.045. That seetion allows an appeal to the city council by any person aggrieved by an administrative officer's interpretation and enforcement of the codes of technical regulation adopted under chapter 12.05 of the city code. Pruitt's failure to appeal the city's decisions regarding the building code, however, does not help analyze whether Pruitt had an obligation to appeal the zoning code ruling. Because we believe the case turns on Pruitt's obligation to appeal the zoning code ruling, the city's argument that Pruitt failed to exhaust under SCC § 12.05.045 is irrelevant. As we explain below, the city's zoning code determination underlies all of its building code determinations. Thus, it does not matter whether Pruitt should have appealed the building code ruling under SCC § 12.05.045.
The city also argues that Pruitt should have appealed the planning and zoning commission's decision denying the variance. But as we explain below in Part IIIC, it would have been inconsistent for Pruitt, while seeking a variance, to argue that his canopy did not in fact violate the zoning code. The variance process gave Pruitt an opportunity to argue that the city should make an exception to its conclusion that a canopy is an "attachment to a building" under SCC § 15.10.140; it did not give him an opportunity to argue that the city was misinterpreting its zoning code. We therefore conclude that Pruitt did not need to appeal the variance denial to exhaust his administrative remedies regarding the city's interpretation of the zoning code.
We review de novo the legal question whether a party exhausted its available administrative remedies.4 Pruitt had standing to appeal to the planning and zoning commission the city's determination that his canopy was an "attachment to a building" within the meaning of SCC § 15.10.140, because that determination prevented Pruitt from lawfully constructing the building as he had proposed.[1136]*11365 The city has not alleged exactly which determination Pruitt should have appealed or when its interpretation of SCC § 15.10.140 became final. We assume that the city contends that Pruitt should have appealed to the commission after he received Olsen's letter informing him that his canopy was an "attachment to a building" that could not extend into the setback. There is no dispute that Pruitt did not appeal from that letter or any later letter arguably deciding that the canopy violated the zoning code.
Pruitt argues that compliance with the city's appellate procedure should be excused "where the appellant doesn't get a notice indicating a final decision has been made and that a stated appeal time has begun to run." He refers by analogy to Appellate Rule 602(a)(2), which states that the appellate period "does not begin to run until the agency has issued a decision that clearly states that it is a final decision and that the claimant has thirty days to appeal." Pruitt contends that the time for appealing the city's interpretation of SCC § 15.10.140 has not yet begun to run because the city never told him that its decision was final, nor did it instruct him that he could appeal under SCC § 15.10.410.
We have interpreted Appellate Rule 602(2)(2) strictly, requiring that to begin the running of the thirty-day appellate period, the agency's decision must explicitly state that it is a final decision.6 Although Appellate Rule 602 does not govern internal administrative agency appeals of the sort present here, it is analogous. The doctrine of fairness requires that an individual must be notified that the agency's decision is final and appealable, if the doctrine of exhaustion is to bar a claim in a later proceeding.7
Moreover, if the recipient is not told explicitly that a determination is final, it can be difficult to determine whether an informal agency action is final and therefore appealable.8 Informal agency decisions, such as those announced in letters, interpretive rules, and policy statements, often cannot be characterized as "final actions" because the decision either does not come from someone with ultimate decision-making authority or because the decision is hedged with language suggesting that the position taken is tentative.9 One commentator has noted that when an agency's determination is expressed informally, courts will determine the "finality" of the informal expression based on what is most equitable in that case.10 Courts will often allow appeals filed after the expiration of the appellate period if the party receiving the informal advice does not realize that such advice was meant to be determinative.11 We agree that a party should not be barred from raising an argument in a later proceeding for failure to exhaust its administrative remedies if it is unclear whether the agency's informal opinion was a final and appealable action.
As noted above, we assume that the city contends that Pruitt should have appealed to the commission after he received Olsen's letter informing him that his canopy was an [1137]*1137"attachment to a building" that could not extend into the setback. Olsen's letter stated: "This office has reviewed your plans for a new building ... it also appears on the building plans that the ... canopy over the store entrance will extend into the setback." The letter then quoted SCC § 15.10.140, stated that "other attachments to a building are specifically prohibited in the setback," and instructed Pruitt to verify that his canopy would not extend into the setback. (Emphasis in original.) The letter did not specify what "this office" refers to but is written on City of Seward letterhead. The letter was signed:
Sincerely,
The City of Seward
Linda-Rae Olsen
City Clerk
Olsen's letter did not inform Pruitt that the city's interpretation of the zoning code was final and appealable. Moreover, the city's zoning code does not specify which office or administrator bears ultimate responsibility for interpreting the code.12 Pruitt therefore had no way to know whether the interpretation expressed in Olsen's letter was the city's final decision or whether he could attempt to persuade a superior that the letter's interpretation of the code was erroneous.
There is also evidence in the record suggesting that the commission was in the process of changing the zoning code during Pruitt's canopy dispute. James's letter to Pruitt stated: "At your request, we have put the topic of setbacks on the Planning and Zoning Commission agenda for their regular meeting on March 6, 2001." In an affidavit, Pruitt said that he discussed the canopy situation with then-City Manager Scott Janke, who told Pruitt that he hoped the setback requirement in industrial zones would be reduced. Pruitt's canopy would have complied with the city's zoning code had the setback requirement been reduced by only two feet. In a later affidavit, Pruitt stated that he learned that the commission had discussed altering the setback requirements at meetings in late 2003.13 This proposed change in the zoning code further indicates that the city's interpretation of the zoning code was not "final." Thus, because the city did not indicate in the Olsen letter that it was making a final decision and because the city suggested to Pruitt that it might change the zoning code in a way favorable to him, the city did not put Pruitt on notice that, by not appealing the city's determination that his canopy was a structure under SCC § 15,10.140, he would later be precluded from defending an enforcement action if the city brought one.
Appellate Rule 602(a)(2) also requires agencies to inform parties of their right to appeal to the superior court within thirty days. Neither the city's letters notifying Pruitt that his eanopy violated SCC § 15.10.140 nor the building permit prohibiting the canopy advised Pruitt that he could appeal those decisions. The city also did not inform Pruitt of the appellate process outlined in SCC § 15.10.410.
The city first referred to SCC § 15.10.410 in its summary judgment motion in the superior court enforcement action. The only city communication to Pruitt mentioning a right to appeal was the letter from Dave Calvert that stated: "As always, you can appeal this decision to the City Council if you so desire." But the subject of Calvert's letter was not SCC § 15.10.140; instead, Calvert's letter informed Pruitt that he was in violation of the building code, not the zoning code. It is the zoning code that contains the setback requirement.14 Thus Pruitt was not informed [1138]*1138of his right to appeal the city's interpretation of the zoning code before the city commenced the enforcement action.
The city argues that Ben Lomond, Inc. v. Municipality of Anchorage15 forbids Pruitt from defending the enforcement action because Pruitt did not exhaust his administrative remedies. In that case, a municipal zoning official revoked building permits previously issued to Ben Lomond for construction of an apartment complex.16 The zoning official then explained to Ben Lomond that it had the right to administratively appeal the denial of its building plan.17 Ben Lomond chose not to appeal but later brought a separate superior court action for deprivation of property without due process.18 We held that Ben Lomond was barred from bringing its claim because it had failed to exhaust its administrative remedies when it chose not to appeal the zoning official's decision.19
Ben Lomond is distinguishable in two significant ways. First, the municipal zoning official, after denying the proposed site plan, explained to Ben Lomond that the decision could be appealed.20 Here there is no suggestion that the city ever told Pruitt, even informally, of the applicable appellate process or that it notified him that a final decision had been made. Second, Ben Lomond initiated an independent action in superior court alleging that the municipal official's zoning decision violated its constitutional rights.21 Here, the city brought the enforcement action; Pruitt is merely attempting to defend that action.
Because the city did not inform Pruitt that its decision was final, the exhaustion doctrine does not bar Pruitt from defending against the city's enforcement action.
B. Pruitt Is Not Collaterally Estopped from Challenging the City's Interpretation of SCC § 15.10.140.
The planning and zoning commission's denial of Pruitt's variance application ruled that "canopies or marques which extend out from a building are attachments to a building and clearly prohibited in the setback." The city contends that because Pruitt did not appeal the denial of his variance application, he is foreclosed from arguing that a canopy is not an attachment under SCC § 15.10.140.
The doctrine of collateral estoppel or "issue preclusion" prevents a party from raising a previously adjudicated issue in a later proceeding.22 Four requirements must be met for collateral estoppel to apply: (1) the party against whom issue preclusion is sought was a party in the previous action; (2) the identical issue was previously decided; (3) a final judgment on the merits was issued; and (4) the judgment depended on resolution of the issue in question.23
We review de novo the legal question whether collateral estoppel applies.24
The commission's denial of Pruitt's variance application does not meet the requirements for collateral estoppel because the denial was not dependent on the commission's finding that a canopy was an "attachment" under SCC § 15.10.140. Seward City Code § 15.10.325(d) requires satisfaction of seven conditions for a variance. The commission found that Pruitt met only two of the conditions. At least one condition that Pruitt failed to satisfy was unrelated to whether Pruitt's canopy was an attachment under SCC § 15.10.140. The commission is required to find that a requested variance is "the minimum variance necessary to permit the reasonable use of the land or struc[1139]*1139ture." 25 Because Pruitt's property was also being used for boat storage, the commission found there was reasonable use of his property that did not require a variance. The commission could have denied Pruitt's variance application solely because this condition was not met.26 We therefore cannot say that the commission's denial of Pruitt's variance application depended on its finding that a canopy is an attachment to a building under SCC § 15.10.140, and Pruitt is therefore not collaterally estopped from arguing that a canopy is not an attachment to a building.
C. It Is Necessary To Give Pruitt Opportunity To Obtain the Commission's - Interpretation - of SCC § 15.10.140.
We ordinarily give "great weight" to a zoning board's interpretation of its own zoning code and accept its interpretation when the board supplies a reasonable basis for it.27 This deference is based on a zoning board's expertise in administering zoning ordinances.28 When presented with a question of law that does not invoke agency expertise, however, a reviewing court will substitute its judgment for that of a zoning board.29
Pruitt argues that the city's interpretation of SCC § 15.10.140 in the enforeement proceeding is not supported by the text of the ordinance. Seward City Code § 15.10.140 states in part:
Setback. The required minimum distance from right-of-way or lot line that establishes the area within which only fencing, landscaping, driveways, parking and similar uses are permitted. Any structure including, but not limited to decks, stairways, porches or other attachments to a building are specifically prohibited in the setback. Building eaves are permitted to extend into the setback a maximum of two feet.
[[Image here]]
Structure. Anything constructed or erected on the ground or attached to something having location on the ground, including, but not limited to, buildings, towers, and sheds. Fences, restraining walls less than three feet in height, signs, and similar improvements of a minor character are excluded.
Pruitt argues that a canopy is neither a "structure" nor an "attachment." The city contends that we should defer to the interpretation the planning and zoning commission gave SCC $ 15.10.140 in denying Pruitt a variance.
When it denied Pruitt's variance request, the commission reasoned that "canopies or marques which extend out from a building are attachments to a building and clearly prohibited in the setback." But Pruitt did not have the opportunity to argue to the commission that a canopy is not an attachment to a building before the commission entered this ruling. It would have been inconsistent for him, in context of seeking a variance, to argue that his canopy did not in fact violate the zoning code.30 Also, the key issue in the enforcement case is whether Pruitt's canopy violated the zoning code; the commission did not have to decide this issue in order to deny Pruitt's variance application.31 Because the commission did not have to resolve Pruitt's present claim that the city's interpretation of the zoning code was erroneous, and because the commission's ruling was not necessary to decide the variance application, the commission's ruling on the [1140]*1140variance application is not entitled to deference in the enforcement proceeding.32
The superior court used its independent judgment to determine that "(there is no question that the canopy is an attachment to a structure." The court held that Pruitt's canopy violated the "plain language" of SCC § 15.10.140. But whether the canopy violated the setback ordinance is not clear. Section .140 is not so clear that we can say, as a matter of law, that a canopy is an "attachment to a building." Moreover, according to Pruitt, the canopy only intruded into the twenty-foot setback by about twenty-four inches. The ordinance allows building eaves to protrude into a setback up to two feet.33 It appears possible that the canopy is sufficiently similar in form and function to building eaves that the canopy should be considered to be within the eaves exception.34 According to the ordinance, the purpose of setbacks is "to ensure sufficient open area for snow accumulation, sunlight, views, privacy, fire separation and visual relief between structures.35 Pruitt argues that none of these purposes is compromised by his canopy, protruding as it does only two feet into a twenty-foot setback. He notes that "[oln any building and certainly ones of one-story, an eave has the same impact on the underlying land as the canopy at issue here." Pruitt also argues that his canopy is a "minor improvement," more like a sign than the ground-based "decks, stairways or porches" mentioned in section .140. In summary, he argues that, in view of the purposes of the setback requirement and the nature of both permitted and prohibited improvements therein, it would be irrational to prohibit canopies that extend two feet into the setback.36 Because it is unclear whether the canopy violated the setback ordinance, we are unable to affirm the superi- or court's conclusion that it did. Given the city's reliance on the exhaustion doctrine, and its failure to tell Pruitt it had made a final, appealable decision interpreting seetion .140, the court, rather than substitute its judgment for that of the commission, should have given Pruitt an opportunity to obtain the commission's interpretation.37 Whether the ordinances permit the canopy should be decided in the first instance by the commission. In any subsequent judicial review of the commission's decision on this issue, a deferential standard of review should be employed and the decision will be subject to reversal only if it is unreasonable.38
It does not appear that the commission has had an opportunity to interpret SCC § 15.10.140 as applied to Pruitt in light of the parties' present arguments. The superior court on remand should therefore enter an order holding the enforcement action in abeyance until Pruitt has an opportunity to ask the commission to interpret SCC § 15.10.140. The superior court should instruct Pruitt that he has ten days from entry of that order in which to file with the commission an appeal under SCC § 15.10.410 from the city's interpretation of section .140. If he fails to comply with the city's appellate procedure, the abeyance order should be vacated, and the city may argue the exhaustion issue. Otherwise, the enforcement action should be held in abeyance until Pruitt ex[1141]*1141hausts his administrative remedies or he abandons the administrative appeals. This remedy will give Pruitt an opportunity to obtain the ruling from the commission that he could have sought with a timely appeal had he been told that the city had reached a final, appealable decision. If there is an administrative appeal to the superior court from a final agency determination, the superior court assigned to that appeal can consider whether to consolidate the two cases.
D. The City's Four Causes of Action Against Pruitt all Relate to the City's Interpretation of the Zoning Code.
The city's enforcement action pleaded four separate causes of action against Pruitt: (1) he violated the building code by using and cccupying his building without a certificate of occupancy; (2) he violated the building code by not conforming to the permit that required the building be constructed without the canopy or in a manner so that the canopy did not extend into the setback; (8) his canopy extended into the twenty-foot setback required in the city's zoning code; and (4) he violated the building code by constructing the loading dock without a permit. The superior court found Pruitt liable on all four counts.
All four causes of action depend on the city's interpretation of the zoning code. Most obviously, the claim that Pruitt's canopy violated the zoning code stems directly from the city's interpretation that a canopy is an attachment to a building within the meaning of SCC § 15.10.140. Calvert's affidavit stated that the building permit did not authorize the canopy because city officials noted that it would violate the zoning code. The canopy's intrusion into the setback was also Calvert's reason for denying a certificate of cecupancy for the building and a building permit for the loading dock. All four causes of action therefore originate in the city's conclusion that the canopy violated the zoning ordinance. Because Pruitt must be given the opportunity to appeal the city's interpretation of "structure" to the commission, the superior court's grant of summary judgment must be vacated as to all four counts.39
IV. CONCLUSION
For the reasons discussed above, the superior court's judgment is VACATED. We REMAND with instructions that the city's enforcement action be held in abeyance until Pruitt has the opportunity to appeal the city's interpretation of SCC § 15.10.140. We therefore also VACATE the city's prevailing party award of attorney's fees.
CARPENETI, J., dissenting.