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Home My WebLink About3.4 Town of Los Altos Hills May 4, 2006 Staff Report to the Planning Commission RE: CONSIDER THE PROPOSED AMENDMENT OF ZONING CODE SECTION 10- 1.208 (BASEMENT DEFINITION). FROM: Brian Froelich, Assistant Planner S-5� APPROVED BY: Carl Cahill, Acting City Manager/Planning Director C. RECOMMENDATION That the Planning Commission: Review the staff report and attached ordinance, consider any revisions, and forward a recommendation to the City Council. BACKGROUND On February 16, 2006 the Planning Commission reviewed a draft basement ordinance. The Commission directed staff to work with the Town Building Official and confirm that the basement ordinance was practical to enforce. Staff has prepared a draft ordinance for Commission review (attached). The draft ordinance clarifies the criteria for the basement floor area exemption. The previous ordinance required the basement ceiling to be below the adjoining natural or finished grade, whichever is lower. Project architects and designers have communicated that this criteria presents difficulty with Building Code compliance. Specifically, Building Code Section 2306.8 requires a separation of six (6)inches from wood to earth (grade). The proposed ordinance requires that the finished floor elevation of the first floor above the basement be no greater than 28 inches above natural or finished grade, whichever is lower. The proposed ordinance omits the basement ceiling requirement (to be below adjoining grade) because basement ceiling/finished floor thickness can vary with design and the aforementioned building code section presents design difficulties. All maximum height standards apply to buildings that incorporate basements. Please see the attached draft basement ordinance and the associated diagram. CEQA Status: Categorical Exemption per Section 15308 - Actions of Regulatory Agencies for the Protection of the Environment. ATTACHMENTS 1. Proposed Basement Ordinance 2. Basement Diagram 3. February 16, 2006 Planning Commission Staff Report ATTACHMENT I BASEMENT ORDINANCE Sec. 10-1.208 Basement "Basement" shall mean a floor level, or portions thereof, which has: i (1) all portions directly below a building; and (2) the finished floor elevation of the builing level above shall not be greater than 28 inches above the adjoining natural or finished grade, whichever is lower; and (3) have at least 3 sides, or at least 75% of its perimeter length wholly underground. That side of the basement not wholly underground shall not be located on any side of a lot abutting one side of a road. Daylighted basements shall comply with all height and setback requirements of this ordinance. Basements including cellars and bunkers, which are not located within the footprint of the building above, may be permitted by the Planning Commission when it finds that such structures do not encroach in setbacks, are a minimum of 18 inches below natural grade, are wholly underground except for required exiting, lighting and ventilation and are counted as development area except when placed under a surface already counted as development area. I I� ATTACHMENT Z I FINISHED FLOOR I . N I14 I 18" FLOOR JOIST - c0 61 X i 4 E FINISH PAD SLOPE AWAY �p FROM FND g 251- MIN. _ \ NATURAL OR FINISHED ADE (WHICHEVER 15 LOWER) basement RETAINING WALL /o\:i�\\�i�i�i . i . . . A Retaining Floor Frame Detail NTS ArrPtC iMENT 3 TOWN OF LOS ALTOS HELLS February 16, 2006 Staff Report to the Planning Commission RE: DISCUSSION TO CONSIDER AMENDING ZONING CODE SECTION 10-1.208 (BASEMENT DEFINITION). FROM: Brian Froelich, Assistant Planner APPROVED BY: Carl Cahill, Planning Director RECOMMENDATION: That the Planning Commission: Discuss the proposed revision and direct staff to prepare text amendments to the ordinances as determined to be necessary. BACKGROUND The purpose of this item is to clarify the basement definition with regard to basement ceiling. Particularly, ceiling height has been an issue with at least two recent projects and during otherpre-application meetings for proposed or modified basements. Architects and designers have been proposing artificially lowered ceilings for the purpose of exempting floor area. DISCUSSION Currently,Zoning Code Section 10-1.208 states: Sec. 10-1.208 Basement I "Basement" shall mean a floor level, or portions thereof, which is (1) directly under a building; and (2) have its entire height (vertical distance measured from bottom of the basement slab to the ceiling above)beneath the adjoining natural or finished grade, whichever is lower; and (2) have at least 3 sides, or at least 75% of its perimeter length wholly underground. That side of the basement not wholly underground shall not be located on any side of a lot abutting one side of a road. Basements, including cellars and bunkers, which are not located within the footprint of the building above, may be permitted by the Planning Commission when it finds that such structures do not encroach in setbacks, are a minimum of 18 inches below natural grade, are wholly underground except for required exiting, lighting and ventilation and are counted as development area except when placed under a surface already counted as development area. Staff Report to the Planning Commission February 16,2006 Page 2 of 2 The current code section does not define basement ceiling or limit the vertical distance between the basement ceiling and finished floor above. Specifically, this could be problematic with daylighted basements because the current code section allows enlargement of visible portions of the building that contribute to overall bulk and massing but are not limited by a floor area maximum. The Town's building official has noted that the vertical dimension typically required to accommodate flooring material and joists is no greater than 18 inches. Therefore, it is recommended that the Planning Commission review and discuss the proposed new language to the basement ordinance as follows: Sec. 10-1.208 Basement "Basement" shall mean, or portions thereof, which is (1) directly under a building; and (2) have its entire height (vertical distance measured from bottom of the basement slab to the ceiling above)beneath the adjoining natural or finished grade, whichever is lower; and (3) have at least 3 sides, or at least 75% of its perimeter length wholly underground. That side of the basement not wholly underground shall not be located on any side of a lot abutting one side of a road. Basements, including cellars and bunkers, which are not located within the footprint of the building above,may be permitted by the Planning Commission when it finds that such structures do not encroach in setbacks, are a minimum of 18 inches below natural grade, are wholly underground except for required exiting, lighting and ventilation and are counted as development area except when placed under a surface already counted as development area. For the purposes of this Section 10-2.108 and floor area calculations per Section 10-1.503, "ceiling" shall be defined as a horizontal plane 18 inches below and parallel to the finished floor elevation of the building level immediately above the basement level. SUNIlVIARY The current code needs further clarification to avoid designs that exempt floor area through the use of false ceiling design. The proposed basement ordinance provides clarification of the basement standards and the proposed change sets a limit. Staff will provide graphics for discussion at the public hearing. CEQA Status: Categorical Exemption per Section 15308 - Actions of Regulatory Agencies for the Protection of the Environment. ATTACHMENT 1. Section views of a project with an artificially lowered ceiling.