In the issuance of building permits, a city building *718inspector acts as an administrative agent and must follow the provisions of the zoning ordinance. Lee v. Board of Adjustment, 226 N.C. 107, 37 S.E. 2d 128. Where the applicant meets all the requirements of the ordinance he is entitled to the issuance of a permit as a matter of right and it may not lawfully be withheld. Mitchell v. Barfield, 232 N.C. 325, 59 S.E. 2d 810. A board of adjustment, authorized by G.S. 160-178, is also an administrative agency which acts in a quasi-judicial capacity, its principal function being to issue variance permits so as to prevent injustice by a strict application of the ordinance. Lee v. Board of Adjustment, supra. The board is not a law making body and has no power to amend the zoning ordinance either to permit the construction of a building prohibited by the ordinance or to prohibit the construction of one permitted by the ordinance. In Re Markham, 259 N.C. 566, 131 S.E. 2d 329; Bryan v. Wilson, 259 N.C. 107, 130 S.E. 2d 68; Chambers v. Board of Adjustment, 250 N.C. 194, 108 S.E. 2d 211; In Re O’Neal, 243 N.C. 714, 91 S.E. 2d 189; James v. Sutton, 229 N.C. 515, 50 S.E. 2d 300; Lee v. Board of Adjustment, supra. Thus, if the ordinance of the City of Statesville permits the construction in an M-l general industrial district of the proposed asphalt plant, the building inspector acted properly in the issuance of the building permit in this instance and the Board of Adjustment had no authority to revoke the permit. We turn, therefore, to the ordinance to see whether such a building is authorized in such district.
A zoning ordinance, like any other legislative enactment, must be construed so as to ascertain and effectuate the intent of the legislative body. Bryan v. Wilson, supra. A zoning ordinance, however, is in derogation of the right of private property and provisions therein granting exemptions or permissions are to be liberally construed in favor of freedom of use. In Re Couch, 258 N.C. 345, 128 S.E. 2d 409; In Re Appeal of Supply Co., 202 N.C. 496, 163 S.E. 462.
The ordinance in question first states, in general terms, that it is intended to permit in an M-l general industrial district any use which is not “inherently obnoxious to urban areas because of noise, odors, smoke, light, dust or the use of dangerous materials.” (Emphasis added.) It does not, however, stop with this declaration of intent. It goes further and expressly provides that “mixing plants for concrete or paving materials” are permitted in such districts. Asphalt is obviously a paving material. Whether this provision in the ordinance be regarded as a legislative provision for an exception to the general prohibition of a use which is inherently obnoxious to urban areas because of noise, odors, smoke, light, dust, or the use of dangerous materials, or be regarded as a declaration by the legislative *719body that an asphalt mixing plant is not inherently obnoxious, the ordinance expressly permits the construction and use of an asphalt plant in an M-l general industrial district. The Board of Adjustment has no authority to prohibit that which the city council has expressly permitted in the ordinance. Its order directing the revocation of the permit issued by the building inspector was, therefore, in excess of its authority.
This is not to say that an asphalt plant constructed and operated in an M-l general industrial district is not subject to regulations, otherwise valid, designed to prevent its operation in such a manner as to produce obnoxious noise, odors, smoke, or dust. The question is not before us in the present case. See Mitchell v. Barfield, supra.
It is also unnecessary for us to consider the contention of the appellant that the protestants notice of appeal to the Board of Adjustment was not filed within the time allowed therefor; or its contention that, having purchased the property in good faith without knowledge of the contemplated appeal and after waiting 15 days to see if such appeal would be taken, the appellant acquired a right to the permit .which it would not otherwise have.
The order of the superior court is hereby reversed. The superior court will remand this proceeding to the proper city authorities with direction that a permit issue, unless cause for denial of such permit has arisen since the order entered by the Board of Adjustment.