§ 8.100 — San Mateo County Zoning Code

8.100.040 - Minimum Building Site. ¶

The minimum building site shall be determined in accordance with the following definitions and tables:

(a) “Contour Interval” shall mean the difference in elevation between adjacent contour lines on a topographical or planimetric map.
(b) “Average Percent of Slope” shall mean the percent of slope as computed by the following formula:

S = 100 IL

Where S = average percent of slope; I = contour interval in feet; L = summation of length of all contour lines in feet; A = area in square feet of parcel being considered. In calculating the average percent of slope, any part of the parcel will be excluded from the calculation if the owner so elects; however, if the owner makes this selection then in determining land use densities applicable to the parcel only the land used in the slope calculation shall be used in calculating allowable density. If the owner chooses this option, then land excluded from the calculation of density must remain undeveloped and a deed restriction recorded.

MINIMUM BUILDING SITE
Average Slope of Parcel (percent)	Minimum Area (square feet)
0 - 17	12,000
18	13,000
19	14,000
20	15,000
21	16,000
22	17,000
23	18,000
24	19,000
25	20,000
26	22,000
27	24,000
28	26,000
29	28,000
30	30,000
31	33,000
32	36,000
33	39,000
34	42,000
35	45,000
36	48,000
37	51,000
38	54,000
39	57,000
40	60,000
41	63,000
42	66,000
43	69,000
44	72,000
45	75,000
46	78,000
47	81,000
48	84,000
49	87,000
50 and over	90,000

When new divisions of land are proposed, the minimum size of each new parcel shall be based on the average slope of the land within each new parcel proposed in the land division. Areas devoted to public or private roads, rights-of-way, or access easements shall not be included in parcel size calculations.

After land division, if the maximum number of new parcels permitted by average slope measurement is created, a separate document shall be recorded that specifies that newly created parcels cannot be further divided into smaller parcels. If the maximum number is not created, leaving potential for future land division, the applicant must specify in a separate recorded document which parcels will eventually be divided.