— The State seeks review of a Court of Appeals decision reversing the conviction of Gary William Ross (Defendant) for manufacture and possession of a controlled substance. At issue is whether a police officer’s observation of growing marijuana during a warrantless entry on Defendant’s property constituted an unlawful search under the Fourth Amendment, United States Constitution, or article I, section 7 of the Washington Constitution. We find that it did and affirm the Court of Appeals.
Facts
In February 1995, Pierce County Deputy Sheriff John Bananola went to 8310 Woodbourne Road S.W. to investigate an anonymous informant’s tip regarding a marijuana grow operation at that location. While there, he saw a blue Chevy Blazer in the driveway and learned that it was registered to the Defendant.
On March 24, 1995, at around 8:30 p.m., Deputy Bananola, along with Deputy Jeff Reigle, returned to Defendant’s residence. They were in an unmarked car and wearing street clothes. The house and detached garage are located between two streets running north and south, Luzader Street on the west and Woodbourne Road S.W. curving east at the southeast corner of the property. The property has two entrances. They parked their car along Luzader Street and walked up the driveway to the corner of Defendant’s garage. When they reached the corner of Defendant’s garage, Deputy Reigle smelled the odor of growing marijuana. Deputy Bananola did not smell marijuana but did notice mold and mildew on the inside of a garage window. Deputy Reigle immediately turned around and started walking back to the car, motioning Deputy Bananola to follow. Later that evening, Deputy Bananola *308indicated to Deputy Reigle that he did not feel comfortable stating in an affidavit that he had smelled growing marijuana and wanted to double check the garage for evidence of growing marijuana. The deputies returned to the Defendant’s residence at 12:10 a.m. and again approached the garage from the driveway on Luzader. They confirmed the smell of marijuana and left without approaching the front door or attempting to contact the residents.
Deputy Bananola filed an affidavit of probable cause and obtained a search warrant which was executed on March 31. Police found growing marijuana plants in the garage and house and packaged cut marijuana in the house. Defendant was charged with unlawful manufacture of a controlled substance and possession of a controlled substance. RCW 69.50.401. Prior to trial, Defendant moved to suppress the evidence on the grounds that the deputies had not been on his property lawfully when they obtained probable cause. The trial court denied the motion, finding that the deputies “were on legitimate business, investigating an allegation of a crime,” that they “used the most apparently normal, most direct access route to the house,” that Defendant did not have a “reasonable expectation of privacy in the area from which the deputies smelled the growing marijuana,” and that “[s]uch area was impliedly open to the public.” Clerk’s Papers (CP) at 614. The case was tried on stipulated facts and the Defendant was convicted.
On appeal, the Court of Appeals reversed the Defendant’s conviction finding that the deputies’ initial intrusions onto his property exceeded the scope of an implied invitation. State v. Ross, 91 Wn. App. 814, 819-20, 959 P.2d 1188 (1998). The court relied on the following facts: (1) the discovery was not accidental because the deputies entered Defendant’s property specifically to investigate an alleged marijuana grow operation; (2) the deputies acted secretly by going on the property at night, in plain clothes and an unmarked car, and without identifying themselves; and (3) the deputies used a side-entry rather than the most direct *309access route to the front door, which according to the court would have been from Woodbourne. Ross, 91 Wn. App. at 820. This court granted the State’s second motion for discretionary review.
Analysis
The first argument raised by the State is that the Court of Appeals improperly reversed the trial court’s unchallenged findings of fact. Specifically, the State argues that the court disregarded the trial court’s finding that the deputies had used the most direct route to the residence, finding instead that the driveway off Luzader was a side-entrance. Because the Defendant did not assign error to the trial court’s finding, the State contends that the Court of Appeals erred when it rejected the unchallenged findings. As the State asserts, unchallenged findings of fact are verities on appeal and an appellate court “will review only those facts to which error has been assigned.” State v. Hill, 123 Wn.2d 641, 647, 870 P.2d 313 (1994).
The Defendant claims that the finding at issue was really a legal conclusion since it was found in the section entitled, “Reasons for the Admissibility of Evidence.”1 Alternatively, he argues that he sufficiently challenged the trial court’s factual findings by objecting at the trial court level or that the Court of Appeals was free to review the trial court’s factual findings even though he technically failed to assign error in compliance with RAP 10.3(a)(3). He relies on State v. Olson, 126 Wn.2d 315, 893 P.2d 629 (1995).
Turning first to the Defendant’s technical argument, even if the trial court had denominated its finding a “conclusion of law,” it would nevertheless be a factual finding and this court would review it as such. See Willener *310v. Sweeting, 107 Wn.2d 388, 394, 730 P.2d 45 (1986). The finding here, that the deputies took the most direct route to the residence, is necessarily a factual question. Moreover, it is a finding that is based on many other factual findings that were so denominated by the trial court.2 The Defendant did not assign error to any of the supporting factual findings.
As to whether the Defendant’s objections in the trial court were sufficient to preserve error for appellate review, the Defendant himself recognizes the requirements of RAP 10.3(a)(3) that appellant’s brief contain a “separate concise statement of each error” “together with the issues pertaining to the assignments of error.” However, even assuming that Defendant’s objections to the trial court sufficiently preserved his challenge to the fact at issue, an appellate court is limited to determining whether the challenged fact is supported in the record by substantial evidence. Hill, 123 Wn.2d at 647. Here, substantial photographic and testimonial evidence supported the trial court’s findings regarding the appearance of the two entrances. In turn, these factual findings support the finding that the deputies used the most direct access route to the Defendant’s residence. We agree with the State that the Court of Appeals erred when it rejected the trial court’s finding.
*311Finally, the Defendant’s argument that an appellate court may review unchallenged facts in spite of his failure to comply with RAP 10.3(a)(3) is not supported by Olson. In Olson, this court held that the Court of Appeals does not abuse its discretion by considering the merits of an appeal where the appellant’s challenge is clear but there are technical flaws in the appellant’s compliance with the Rules of Appellate Procedure. Olson, 126 Wn.2d at 323. The failure to challenge findings of fact is not a technical flaw within the meaning of Olson.
We turn now to the central issue in this case: whether the observations made by Deputy Bananola and contained in the affidavit supporting the search warrant were made in the course of an unlawful search. The Court of Appeals found that the deputy’s intrusions exceeded the scope of an implied invitation, thus constituting a search.
The State argues that the Court of Appeals’ decision is in conflict with a number of this court’s opinions discussing the “open view” doctrine. The State contends that as long as an officer remains in an area that is impliedly open to the public, the officer will not intrude upon a constitutionally protected expectation of privacy unless the officer uses a particularly intrusive method of viewing or observing. Because the deputies here did not depart from an area impliedly open to the public, the State claims, and used only their sense of smell and sight unaided by any enhancement device, they did not invade the Defendant’s reasonable expectation of privacy.
The Defendant argues, however, that the police entry onto his property did not satisfy the requirements of the “open view” doctrine. As a result, the officers conducted an unlawful search, the result of which cannot be used to establish probable cause for the issuance of a search warrant.
It is well-established that if information contained in an affidavit of probable cause for a search warrant was *312obtained by an unconstitutional search, that information may not be used to support the warrant. State v. Johnson, 75 Wn. App. 692, 879 P.2d 984 (1994). The affidavit in support of the warrant in this case relies on the evidence gathered by the deputies during their two entries onto the Defendant’s property. The trial court, with the State’s agreement, excised from the affidavit Deputy Reigle’s allegation that he smelled marijuana when he entered the property at 8:30 p.m. Accordingly, our analysis will be limited to Deputy Bananola’s observations. State v. Hoke, 72 Wn. App. 869, 872-73, 866 P.2d 670 (1994).
We begin with the well-recognized principle that warrantless searches are per se unreasonable under both the Fourth Amendment and article I, section 7 of our state constitution unless they fall within a few specifically established and well-delineated exceptions. State v. Myers, 117 Wn.2d 332, 337, 815 P.2d 761 (1991). A person’s home has generally been viewed as the area most strongly protected by the constitution. State v. Rose, 128 Wn.2d 388, 391-92, 909 P.2d 280 (1996); State v. Young, 123 Wn.2d 173, 189, 867 P.2d 593 (1994); State v. Chrisman, 100 Wn.2d 814, 820, 676 P.2d 419 (1984) (citing Payton v. City of New York, 445 U.S. 573, 100 S. Ct. 1371, 63 L. Ed. 2d 639 (1980)). The curtilage of a home is “ ‘so intimately tied to the home itself that it should be placed under the home’s “umbrella” of Fourth Amendment protection.’ ” State v. Ridgway, 57 Wn. App. 915, 918, 790 P.2d 1263 (1990) (quoting United States v. Dunn, 480 U.S. 294, 301, 107 S. Ct. 1134, 94 L. Ed. 2d 326 (1987)).
As this court stated in State v. Seagull, 95 Wn.2d 898, 902, 632 P.2d 44 (1981), however, “[i]t is clear that police with legitimate business may enter areas of the curtilage which are impliedly open, such as access routes to the house.” (Footnote omitted.) An officer with legitimate business, when acting in the same manner as a reasonably respectful citizen, is permitted to enter the curtilage areas of a private residence which are impliedly open, such as access routes to the house. Seagull, 95 Wn.2d at 902; Rose, *313128 Wn.2d at 392. Under the “open view” doctrine, detection by an officer who is lawfully present at the vantage point and able to detect something by utilization of one or more of his senses does not constitute a search within the meaning of the Fourth Amendment. Seagull, 95 Wn.2d at 901; Young, 123 Wn.2d at 182. In Seagull, this court considered a number of facts in determining whether an officer has substantially and unreasonably departed from an area impliedly open to the public or has engaged in a particularly intrusive method of viewing such that the scope of the implied invitation has been exceeded and an unconstitutional search has occurred. Seagull, 95 Wn.2d at 902-03.
Before reaching the Seagull inquiry, however, the first requirement of the “open view” doctrine must be satisfied. That is: the officer must be conducting legitimate business when he enters the impliedly open areas of the curtilage.
In this case, the trial judge concluded that Deputies Reigle and Bananola “were on legitimate business, investigating an allegation of a crime.” CP at 614. In reaching this conclusion, the trial judge considered the 8:30 p.m. and 12:10 a.m. entries together. This was incorrect. Deputy Reigle’s observation regarding the smell of marijuana made during the 8:30 p.m. entry was stricken from the affidavit of probable cause, leaving only Deputy Bananola’s statement about mold and mildew on the window of the garage which would not support probable cause for a search warrant. To uphold the search pursuant to the warrant then, the State must demonstrate that Deputy Bananola entered the Defendant’s property at 12:10 a.m. to conduct legitimate business.
The affidavit of probable cause states that Deputy Bananola did not detect the smell of marijuana during the 8:30 p.m. entry. In testimony, Deputy Reigle stated that he and Deputy Bananola returned to the Defendant’s residence at 12:10 a.m. so that Deputy Bananola could confirm the smell of marijuana for purposes of preparing the affidavit of probable cause. Thus, contrary to the dissent’s view *314that the officers were on legitimate police business investigating criminal activity, the officers’ purpose was not to investigate criminal activity but to obtain information to prepare the affidavit in order to obtain a search warrant.
In a case very similar to this, State v. Johnson, the Court of Appeals found that Drug Enforcement Agency (DEA) agents were not lawfully on the Defendant’s property. There the court observed:
the DEA agents were not using the road merely as a way to gain access to the Johnsons’ house. Rather they were using it as the most convenient route on which to trespass on the Johnsons’ property. The record demonstrates that the DEA agents never attempted to approach the house or contact the occupants. Indeed, it is obvious that they had no intention of doing so; rather they furtively entered the Johnsons’ property under cover of darkness in an apparent effort to look for a marijuana grow operation. Unlike the officers in Seagull and [State v.] Vonhof, [51 Wn. App. 33, 751 P.2d 1221 (1988), review denied, 111 Wn.2d 1010, cert. denied, 488 U.S. 1008 (1989),] their only purpose was to conduct a search and gain information by trespassing on private property
Johnson, 75 Wn. App. at 704-05. As in Johnson, the deputies here entered the Defendant’s property for the express, and sole, purpose of searching for evidence of a marijuana grow operation in order to obtain a search warrant. The deputies entered the property at 12:10 a.m., an hour when no reasonably respectful citizen would be welcome absent actual invitation or an emergency. They had no intention of contacting the Defendant. From the facts presented here we can conclude only that the deputies were not conducting legitimate business when they returned to the Defendant’s property at 12:10 a.m. and were, therefore, not lawfully on the property. We conclude that the evidence gathered during the 12:10 a.m. entry must be suppressed.
The remaining question is whether the warrant was nevertheless supported by untainted evidence in the affidavit. Johnson, 75 Wn. App. at 709. Only Deputy *315Bananola’s observation about mold and mildew on the window of the garage and the anonymous tip remain. An affidavit establishes probable cause for a search warrant if it sets forth facts sufficient to allow a reasonable person to conclude there is a probability that the defendant is involved in criminal activity and evidence of that activity will be found at the place to be searched. Young, 123 Wn.2d at 195. The untainted information in this case, standing alone, does not establish probable cause. Accordingly, the evidence seized pursuant to the warrant must be excluded. Johnson, 75 Wn. App. at 709.
The Court of Appeals is affirmed.
Smith, Johnson, and Alexander, JJ., concur.
Contributing to the confusion is the trial court’s treatment of the facts in State v. Seagull, 95 Wn.2d 898, 632 P.2d 44 (1981), as factors used to determine whether the officer has exceeded the scope of an implied invitation. As this court noted in Seagull, “[w]hat is reasonable cannot be determined by a fixed formula. It must be based on the facts and circumstances of each case.” Id. at 903 (citing Ker v. California, 374 U.S. 23, 33, 83 S. Ct. 1623, 10 L. Ed. 2d 726 (1963)).
Specifically, the trial court found that (1) a shrub on the street side of the Woodboume Rd. S.W. gate had grown to partially overlap such gate; (2) the grass on the street side of such gate revealed no path to such gate; (3) the grass on the street side of the Woodbourne Rd. S.W. gate was brown and yellow and nonmaintained; (4) there was minimal light in the area of Woodboume Rd. S.W. gate, all from neighbors’ lights; (5) the view of the Defendant’s house from the front fence was largely concealed by a large hedge, approximately 12 feet in height; (6) the Defendant’s house was minimally visible around the hedge from the Woodbourne Rd. S.W. gate vantage point; (7) the Defendant’s detached garage and house were clearly visible from Luzader Street with minimal obstructions; (8) the driveway was gravel and directly connected to a walkway made of the same gravel material as it went past the detached garage and through the fence line via the Luzader Street gate; (9) the gravel walkway continued perpendicularly in a direction away from Luzader Street, along the front of the house, leading to the Defendant’s front door and porch, where it then ended; (10) the area around the garage door is not enclosed and is easily accessible to the public or anyone approaching the front door; (11) the floodlight attached to the corner of the garage faced diagonally across the front of the garage and toward the Luzader Street gate, and illuminated part of the gravel driveway and walkway; (12) the residence is situated in such a way that for a person parking on Luzader, the front door is most accessible by walking past the garage. Clerk’s Papers at 614-15.