Opinion by
Judge Craig,The Borough of Dormont appeals an order of the Court of Common Pleas of Allegheny County which reversed a decision of the Dormont Zoning Hearing Board denying a permit to enclose the front porch of the dwelling owned by Edward and Catherine Angle.
The owners’ lot, measuring thirty feet by one-hundred-ten feet, is located in an R 1-A Residential Zone. Since 19271 the property has been subject to a twenty-foot building setback line. In conformity with the ordinance, the edge of the dwelling itself is set back twenty feet from the street line, although a roofed porch extends six feet, seven and one-half inches (GN'A") by twelve feet five inches (12/5") into the front yard.2 The porch extension into the front *54yard, hoAvever, is permissible because tbe porch Avas built in the period before 1968, during which roofed porches Avere permitted to extend into front yard areas Avithout any limitation.
The OAvners applied for a variance to allow them to enclose the porch to create a larger Irving room. The board, which reached no finding nor conclusion concerning any legal nonconformity status, denied the variance. The borough here challenges the action of the trial court which, on appeal to it, rejected the concept of nonconforming use expansion but nevertheless ordered that a variance be granted to enclose the porch.
In zoning cases, where, as here, the trial court has received no additional evidence, our scope of review is limited to determining whether the Board abused its discretion or committed an error of law. Somerton Civic Association v. Zoning Board of Adjustment, 80 Pa. Commonwealth Ct. 173, 471 A.2d 578 (1984).
The owners now contend primarily that they should be permitted to enclose their porch on the basis that it would be a logical, reasonable and natural extension of a nonconforming use, relying upon Yocum Zoning Case, 393 Pa. 148, 141 A.2d 601 (1958). That case involved a two-story frame single family dwelling, later converted into a two-family dwelling, Avith an apartment on each floor, whose westerly front half, an extension of the first floor living room, was approximately seventeen feet from the street line and whose easterly front half was approximately twenty-five feet from the street line, although a porch extended from that point approximately eight feet, so that the front edge of the porch was approximately seventeen feet (17') from the street line. A subsequent zoning ordinance required a front-yard building line of not less than twenty feet. Those owners then sought a permit to extend and enclose the second story *55of their building frontward, so that the front edge of the second floor would coincide with the front edge of the first floor. The Pennsylvania Supreme Court held that such a permit should be granted, not on a variance basis, but because the structural change of the building did not increase “any nonconformity of its use.”
However, the Supreme Court later decided Kline Zoning Case, 395 Pa. 122, 148 A.2d 915 (1959). There, as here, a porch, which was roofed but otherwise unenclosed, extended lawfully into the front yard area in which the zoning ordinance prohibited buildings. The Supreme Court held that there was no basis for allowing a variance to permit the porch to be enclosed and thus transformed into an extension of the dwelling itself within the front yard area. Kline was a variance case, in which the Supreme Court found that purely personal needs — respiratory ailments suffered by the owner’s wife and son — did not constitute a hardship sufficient in legal nature to warrant a variance.
The physical configurations in Kline and in this case are virtually identical. Yocum’s physical facts were somewhat different; there an enclosed living-room section of the dwelling already extended into the front yard area alongside the unenclosed porch.
Like Kline, this present case has involved a variance request from the start. The owner’s appeal to the board was solely on the basis of a variance, the zoning hearing board properly dealt with the variance question, the trial court correctly found no legal nonconforming use basis for extending a living-room as distinguished from a porch, and the trial court’s order reversed the board by granting the variance, essentially upon a theory which Kline rejected, that personal family needs could constitute a sufficient hardship basis for a variance.
*56Yocum, oil the other hand, did not speak to the resolution of such a variance claim. In Yocum, the Supreme Court expressly stated that the “allowance of this building permit is neither the grant of a ‘variance’ nor an ‘exception’ nor an extension of the use of these premises.” (393 Pa. at 155, 141 A.2d at 605.) Instead, the Yocum decision said that allowing the second floor of the building to be extended into the front yard, as far as the first floor already projected, was (1) a “logical, reasonable and natural structural change” which (2) “neither increases any nonconformity of its use,” nor (3) “violates any provision of the zoning ordinance.” Id. at 155, 141 A.2d at 605-6. In itself, “logical” or “reasonable” or “natural structural change” has never been a legal concept warranting construction contrary to zoning ordinance provisions, and, at least in this present case, constructing an enclosure which causes the dwelling itself to project into the front yard area does increase “nonconformity” in that it does contravene the zoning ordinance provision which prohibits buildings in the front yard.
Pennsylvania’s classic nonconforming use expansion doctrine, allowing a nonconforming use for business to “be increased in extent by natural expansion and growth of trade,” Peirce Appeal, 384 Pa. 100, 105, 119 A.2d 506, 509 (1956), cannot provide a doctrinal basis for the virtually automatic structural extension concept which is pressed here because even Yocum held that, with such facts, “we are considering not a nonconforming general use . . . but a building whose juxtaposition on the land renders it nonconforming.” 393 Pa. at 153, 141 A.2d at 605. Such a dimensional nonconformity has no natural expansion right.
Granting what is sought here would render zoning front-yard setback requirements inoperative to prevent the intrusion of building extensions whenever *57some relatively unobstrusive structural element already exists within the yard area sought to be preserved by the setback. Here the existence of a roof over an open porch would become the vehicle for extending the building; by the same reasoning, structural elements such as carports, courtyards, patios or swimming pools — which commonly lie over setback lines — would become automatic bases for the construction of enclosed garages or building extensions within areas sought to be preserved as relatively open spaces.
Kline clearly holds that, when the porch roof is a permitted intrusion in the front yard, a variance to enclose it as a building is not warranted by that circumstance coupled with family convenience. Nor can Yocum be applied here to allow the building extension simply because the extending porch roof, formerly permitted like that in Kline, is now nonconforming dimensionally. A dimensionally-noaconforming structure should not have a greater right of expansion than a dimensionally-conforming structure.
The trial court’s rejection of nonconformity expansion concepts was therefore well founded, but Kline provides an all-fours precedent requiring reversal of the variance grant.
Order
And Now, June 5, 1984, the order of the Court of Common Pleas of Allegheny County, dated January 20, 1983, is reversed.
Zoning Ordinance of Borough, of Dormont, Ordinance No. 935.
The remainder of the porch, almost four feet (4') by twelve feet five inches (12'5") is built behind the twenty-foot (20') building line.