HomeMy WebLinkAbout3.4 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.
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ATTACHMENT Z
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FINISHED FLOOR
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18" FLOOR JOIST -
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FINISH PAD
SLOPE AWAY �p
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RETAINING WALL
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Retaining Floor Frame Detail
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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.