San Mateo Law Library
City of San Mateo Municipal Code.

27.18.050 BUILDING HEIGHT AND DAYLIGHT PLANE.

(a) Maximum height. The maximum height of structures shall be 24 feet measured from existing grade to the building plate line and 32 feet measured from the existing grade to the highest point of the roof. Existing residences that exceed these limits may construct additions in accordance with their existing roof lines but shall not increase the non-conformance with these height limits.

(b) Daylight plane. No structure shall extend above or beyond a daylight plane having a height of twelve (12) feet at each side property line and extending into the parcel at an angle of forty-five (45) degrees, with the following encroachments allowed:

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(1) Television and radio antennas, chimneys, flues, eaves, or skylights;

(2) Dormers or similar architectural features, provided that the horizontal length of all such features shall not exceed a combined total of fifteen (15) feet on each side, measured along the intersection with the daylight plane;

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(3) Gables or similar architectural features, provided that the horizontal length of all such features shall not exceed a combined total of eighteen (18) feet on each side, measured along the intersection with the daylight plane, and provided that the intersection of the gable with the daylight plane closest to the front property line is along the roof line;

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(4) Where the finished first floor of an existing dwelling is more than three (3) feet above existing grade and is being extended by an addition, the initial height of the daylight plane shall be fourteen (14) feet;

(5) Where the slope of a parcel measured between the side property lines at the front setback is fifteen percent (15%) or steeper, the initial height of the daylight plane shall be fourteen (14) feet on the downhill side of the parcel; and

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(6) Where the slope of a parcel measured between the front and rear most points of the structure is fifteen percent (15%) or steeper, the daylight plane shall be measured at the front setback line and each thirty (30) feet thereafter, and the height limits established at these points shall be extended horizontally to the next measurement point.

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