Chapter 17.56
DENSITY COMPUTATIONS
Sections:
17.56.020 Density calculation.
17.56.030 Transfer of residential density.
17.56.040 Residential density transition.
17.56.010 Purpose.
The purpose of this chapter is to implement the comprehensive plan by establishing the criteria for determining the number of dwelling units permitted. (Ord. 2875 § 1.100.010, 2003)
17.56.020 Density calculation.
(1) Net development area, in acres, shall be determined by subtracting the following land area(s) from the gross acres, which is all of the land included in the legal description of the property:
(a) All sensitive land areas:
(i) Land within the 100-year floodplain;
(ii) Land or slopes exceeding 25 percent;
(iii) Drainageways;
(iv) Wetlands;
(v) Fish and wildlife habitats;
(vi) Archaeological sites;
(vii) Federal or state protected areas for listed threatened or endangered species; and
(viii) Designated open space and open space-design review areas;
(b) All land dedicated to the public for park purposes;
(c) All land dedicated for public right-of-way:
(i) Single-dwelling units: allocate 20 percent of gross acres for public facilities; and
(ii) Multidwelling units: allocate 15 percent of gross acres for public facilities;
(d) All land proposed for private streets; and
(e) A lot of at least the size required by the applicable base zoning district, if a lawfully existing use is to remain on the site.
(2) To calculate the net units per acre, divide the number of square feet in the net acres by the minimum number of square feet required for each lot by the applicable zoning district. Lots eligible for detached single-family dwellings or duplexes as allowed by the zoning district shall be treated as one unit per lot for the purpose of density calculations (i.e., the potential second unit on the lot does not burden the calculation).
(3) All density calculations shall comply with the provisions of SHMC 17.56.040, Residential density transition.
For example:
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100.00 acres gross R-7 land |
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less |
38.23 acres |
(one acre flood, one acre hazard, three acres drainage, 10 acres wetlands, three acres park, 20 acres right-of-way, and .23 acre for existing house) |
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61.77 acres net buildable land (6.22 du/acre = 384.21 du) |
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(Ord. 3264 § 2 (Att. A), 2021; Ord. 2875 § 1.100.020, 2003)
17.56.030 Transfer of residential density.
(1) Units per acre calculated by subtracting land areas listed in SHMC 17.56.020(1)(a) from the gross acres may be transferred to the remaining buildable land areas subject to the following limitations:
(a) The number of units which can be transferred is limited to the number of units which would have been allowed on 25 percent of the unbuildable area if not for these regulations;
For example:
38.23 x 25% = 9.96 acres
9.96 acres x 6.22 dwelling units/acre = 59.45 dwelling units
59.45 dwelling units + 384.21 = 443.60 dwelling units/100 acres;
(b) The number of units is limited to 25 percent of the total number of units which could have been constructed on the unbuildable area if not for these regulations; and
(c) The total number of units per site does not exceed 125 percent of the maximum number of units per gross acre permitted for the applicable comprehensive plan designation (maximum 777.5 dwelling units per 100 acres).
(2) Units per acre calculated by subtracting land areas listed in Chapter 17.44 SHMC from the gross acres may be transferred to the remaining buildable land areas on land zoned AR subject to the following limitations:
(a) The number of units which can be transferred is limited to the number of units which would have been allowed on the wetland area, if not for these regulations; and
(b) The total number of units per site does not exceed the maximum number of units per gross acre permitted for the applicable comprehensive plan designation.
(3) All density transfer development proposals shall comply with the development standards of the applicable underlying zoning district unless developed under the provisions of Chapter 17.148 SHMC, Planned Development. (Ord. 2875 § 1.100.030, 2003)
17.56.040 Residential density transition.
(1) Regardless of the allowed housing densities stated in SHMC 17.32.050 through 17.32.160, or in Chapter 17.148 SHMC, this chapter, or Chapter 17.60 SHMC, any property within 100 feet of an established area shall not be developed at a residential housing density greater than 125 percent of the allowed density in the adjacent established area(s). For purposes of this limitation only, the allowed density is as specified in the comprehensive plan land use designation, not as in the zoning district. For example, the property within 100 feet of an established low density residential area (one to five dwellings per acre) shall not be developed at residential densities greater than 6.25 dwellings per acre (6.25 = 5 x 1.25).
(2) Subsection (1) of this section shall not apply with regard to established areas that are separated from the proposed housing development by a collector road or by an arterial road.
(3) Subsection (1) of this section shall not apply where the actual density in the abutting established area exceeds the maximum density allowed under the land use plan map designation for the established area. The density transition still will not exceed 125 percent of the designated abutting established area density. (Ord. 2875 § 1.100.040, 2003)