*747Here, Casey argues that, based upon the report from the board of health substantiating certain of the complaints of Sanitary Code violations, the trial judge was required to find that York had breached the warranty of habitability. Not every violation of the Sanitary Code, however, will support a claim of breach of the warranty. See McAllister v. Boston Hous. Authy., 429 Mass. 300, 305 (1999).4 In her findings, the trial judge specifically found that Casey had failed to prove a breach of the warranty of habitability. Findings of fact will not be set aside unless they are clearly erroneous, bearing in mind the deference that must be given to the trial judge’s opportunity to weigh the credibility of the witnesses. See Mattoon v. Pittsfield, 56 Mass. App. Ct. 124, 139 (2002); Mass.R.Civ.P. 52(a), as amended, 423 Mass. 1402 (1996). “A finding is ‘clearly erroneous’ when although there is evidence to support it, the reviewing court on the entire evidence is left with the definite and firm conviction that a mistake has been committed.” United States v. United States Gypsum Co., 333 U.S. 364, 395 (1948). See Commonwealth v. Boncore, 412 Mass. 1013, 1014 (1992) (“[c]redibility is for the fact finder, not an appellate court”). We conclude, based on our review of the trial judge’s findings of fact and the evidence supporting them, that she did not err in ruling that there was no breach of the warranty of habitability applicable to Casey’s premises.