*566OPINION OF THE COURT
Per Curiam.Final judgment entered November 15, 1979 (Ramos-Lopez, J.) affirmed, with $25 costs. Order dated August 31, 1979 (Ramos-Lopez, J.) affirmed, without costs.
As recognized by the trial court, the Conciliation and Appeals Board, the agency charged with administering the regulation of rents as provided in the Rent Stabilization Law and Code of the Rent Stabilization Association of the City of New York has consistently ruled that the jurisdiction of the Rent Stabilization Law extends to units occupied for combined residential and professional purposes. Courts ordinarily defer to the construction given by administrative agencies of matters within their expertise, if that construction is not irrational or unreasonable (Matter of Howard v Wyman, 28 NY2d 434, 438). No reason is perceived to depart from the board’s general interpretation in this particular case. Tenant is a traveling salesman, necessarily away from his studio apartment for extended periods, but the premises constitute his only residence. The fact that a percentage of the apartment is also utilized for limited commercial purposes, in that tenant is able to conduct the affairs of his solely owned corporation by making telephone calls, doing paperwork and storing samples which he takes on business trips, hardly detracts from the residential character of the occupancy to the extent that petitioner would be jusitified in refusing to tender a renewal lease. We pertinently note that the Court of Appeals has held that an apartment occupied for mixed residential and professional purposes constitutes a housing accommodation subject to the protection of the Emergency Tenant Protection Act of 1974 (Matter of Zeitlin v New York City Conciliation and Appeals Bd., 46 NY2d 992).
Insofar as opinions of the State Administrator construing the rent control laws may be read as inconsistent with the rulings of the Conciliation and Appeals Board, they are not followed inasmuch as the case before us concerns a rent stabilized apartment.
Concur: Dudley, P. J., Tierney and Riccobono, JJ.