HomeMy WebLinkAbout3 - Determination of Zoning - Patio Covers/EnclosuresMarch 16, 2011
STAFF REPORT
To: Honorable Chairwoman and Planning Commission
From: Department of Development Services
Subject: Determination of Zoning pursuant to Chapter 11.5.05
Patio Covers /Enclosures within Residential Zones
SUMMARY OF REQUEST
Staff is requesting a Zoning Determination regarding patio enclosures, pursuant to
Chapter 11.5.05 of the Zoning Code.
DISCUSSION
Recently, Staff received a request from an Old Town resident to construct a patio
enclosure on a property that is presently nonconforming. Historically, Staff has treated
the construction of any solid roofed, enclosed area as additional square footage.
Additions to nonconforming structures are generally prohibited unless approved by a
Variance. Staff informed the applicant that they would need to apply for a Variance to
allow the proposed construction, but advised the resident that there did not appear to
be sufficient grounds to grant such a Variance. Staff then began to research the issue
further and found that the Zoning Code and Building Code have different definitions as
to what constitutes a patio cover versus patio enclosure.
In Zoning Code Section 11.6.05.010, a `Patio Cover' is defined as: "A roofed structure
located between a dwelling and a side or rear property line that shelters an outdoor
area. These Structures are either attached to or detached from a primary dwelling on a
site." Staff has always interpreted this definition as a structure that is not entirely
enclosed (enclosed on not more than three sides). However, the Building Code defines
a `Patio Cover' as: "One -story structures not exceeding 12 feet in height. Enclosure
walls shall be permitted to be of any configuration, provided the open or glazed
(window) area of the longer wall and one additional wall is equal to at least 65 percent
of the area below a minimum of 6' -8" of each wall, measured from the floor. Openings
shall be permitted to be enclosed with: 1.) insect screening, 2.) approved translucent or
transparent plastic not more than 0.125 inch (1/8 ") in thickness, 3.) glass conforming to
the provisions of Section R308, or 4.) any combination of the foregoing." Additionally,
the Building Code states that "Patio covers shall be used only for recreational, outdoor
living purposes and not as carports, garages, storage rooms, or habitable rooms."
Therefore, the Building Code definition would theoretically allow a patio cover to be
"enclosed ", provided the walls are not wood framed construction. Additionally, the
enclosed space cannot be mechanically heated or cooled.
Under the Building Code (California Residential Code) definition of enclosed space, a
screened in patio with windows would be allowed. However, the Zoning Code defines a
screened in patio with windows, if it has four walls, as an enclosure. Staff is seeking
direction from the commission, pursuant to Zoning Code Section 11.5.05.010, regarding
whether the Zoning Code definition of Covered Patio should be revised to conform to
the Building Code definition.
Staff recommends that the Planning Commission discuss the matter and give direction
to Staff as to how to proceed.
For: March 16, 2011
livera, AICP
ig Planner — Development Services
Attachments (2):
1.) Appendix H (Patio Covers), 2010 California Residential Code
2.) Zoning Code definition of Covered Patio.
APPENI H
PA700 COVERS
SECTION AH101
GENERAL
AH101.1 Scope. Patio covers shall conform to the require-
ments of this appendix chapter.
SECTION AH102
DEFINITION
Patio covers. One -story structures not exceeding 12 feet (3657
mm) in height. Enclosure walls shall be permitted to be of any
configuration, provided the open or glazed area of the longer
wall and one additional wall is equal to at least 65 percent of the
area below a minimum of 6 feet 8 inches (2032 mm) of each
wall, measured from the floor. Openings shall be permitted to
be enclosed with (1) insect screening, (2) approved translucent
or transparent plastic not more than 0.125 inch (3.2 mm) in
thickness, (3) glass conforming to the provisions of Section
R308, or (4) any combination of the foregoing.
SECTION AH103
PERMITTED USES
AH103.1 General. Patio covers shall be permitted to be
detached from or attached to dwelling units. Patio covers shall
be used only for recreational, outdoor living purposes and not
as carports, garages, storage rooms or habitable rooms.
SECTION AH104
DESIGN LOADS
AH104.1 General. Patio covers shall be designed and con-
structed to sustain, within the stress limits of this code, all dead
loads plus a minimum vertical live load of 10 pounds per square
foot (0.48 kN /m2) except that snow loads shall be used where
such snow loads exceed this minimum. Such covers shall be
designed to resist the minimum wind loads set forth in Table
R301.2(1).
SECTION AH105
LIGHT AND VENTILATION /EMERGENCY EGRESS
AH105.1 General. Exterior openings required for light and
ventilation shall be permitted to open into a patio structure
con - forming to Section AH101, provided that the patio struc-
ture shall be unenclosed if such openings are serving as emer-
gency egress or rescue openings from sleeping rooms. Where
such exterior openings serve as an exit from the dwelling unit,
the patio structure, unless unenclosed, shall be provided with
exits conforming to the provisions of Section R310 of this
code.
2010 CALIFORNIA RESIDENTIAL CODE
SECTION AH106
FOOTINGS
AH106.1 General. In areas with a frostline depth of zero as
specified in Table R301.2(1), a patio cover shall be permitted to
be supported on a slab on grade without footings, provided the
slab conforms to the provisions of Section R506 of this code, is
not less than 3.5 inches (89 mm) thick and the columns do not
support live and dead loads in excess of 750 pounds (3.34 kN)
per column.
SECTION AH107
SPECIAL PROVISIONS FOR ALUMINUM SCREEN
ENCLOSURES IN HURRICANE -PRONE REGIONS
AH107.1 General. Screen enclosures in hurricane -prone
regions shall be in accordance with the provisions of this Sec-
tion.
AH107.1.1 Habitable spaces. Screen enclosures shall not
be considered habitable spaces.
AH107.1.2 Minimum ceiling height. Screen enclosures
shall have a ceiling height of not less than 7 feet (2134 mm).
AH107.2 Definitions.
SCREEN ENCLOSURE. A building or part thereof, in whole
or in part self - supporting, and having walls of insect screening
and a roof of insect screening, plastic, aluminum, or similar
lightweight material.
AH107.3 Screen enclosures.
AH107.3.1 Thickness. Actual wall thickness of extruded
aluminum members shall be not less than 0.040 inches (1.02
mm).
AH107.3.2 Density. Screen density shall be a maximum of
20 threads per inch by 20 threads per inch mesh.
AH107.4 Design.
AH107.4.1 Wind load. Structural members supporting
screen enclosures shall be designed to support minimum
wind loads given in Table AH107.4(1) and AH107.4(2).
Where any value is less than 10 psf (0.479 kN /in2) use 10 psf
(0.479 kN /m2).
AH107.4.2 Deflection limit. For members supporting
screen surfaces only, the total load deflection shall not
exceed 1/60. Screen surfaces shall be permitted to include a
maximum of 25 percent solid flexible fmishes.
AH107.4.3 Importance factor. The wind factor for screen
enclosures shall be 0.77 in accordance with Section 6.5.5 of
ASCE 7.
615
APPENDIX H
AH107.4.4 Roof live load. The minimum roof live load
shall be 10 psf (0.479 kN /m2).
AH107.5 Footings. In areas with a frost line is zero, a screen
enclosure shall be permitted to be supported on a concrete slab
on grade without footings, provided the slab conforms to the
provisions of Section R506, is not less than 3'/2 inches (89 mm)
thick, and the columns do not support loads in excess of 750
pounds (3.36 kN) per column.
TABLE AH107.4(1)
DESIGN WIND PRESSURES FOR ALUMINUM SCREEN ENCLOSURE FRAMING
WITH AN IMPORTANCE FACTOR OF 0.77a,b,c
LOAD
CASE
WALL
Basic Wind Speed (mph)
100
110
120
130
140
150
Exposure Category Design Pressure (psf)
CB
25
C
B
C
B
C
B
C
B
C
B
Ad
Windward and leeward walls (flow thru) and
windward wall (non -flow thru) L/W = 0 -1
12
8
14
10
17
12
19
14
23
16
26
18
Ad
Windward and leeward walls (flow thru) and
windward wall (non -flow thru) L/W = 2
13
9
16
11
19
14
22
16
26
18
30
21
Be
Windward: Non -gable roof
16
12
20
14
24
17
28
20
32
23
37
26
Be
Windward: Gable roof
22
16
27
19
32
23
38
27
44
31
50
36
ROOF
A11f
Roof -screen
4
3
5
4
6
4
7
5
8
6
9
7
Allf
Roof -solid
12
9
15
11
18
13
21
15
24
17
28
20
For SI: 1 mile per hour = 0.44 m/s, 1 pound per square foot = 0.04791cPa, 1 foot = 304 8 min.
a. Values have been reduced for 0.77 Importance Factor in accordance with Section AH107.4.3.
b: Minimum design pressure shall be 10 psf in-accordance with Section AH107.4.1.
c. Loads are applicable to screen enclosures with amean roof height of 30 feet or less. For screen enclosures of different heights the pressures given shall be adjusted
by multiplying the table pressure by the adjustment factor given in Table AH107.4(2).
d. For Load Case A flow thru condition the pressure given shall be applied simultaneously to both the upwind and downwind screen walls acting in the same direction
as the wind. The structure shall also be analyzed for wind coming from the opposite direction. For the non -flow thru condition the screen enclosure wall shall be
analyzed for the load applied acting toward the interior of the enclosure.
e. For Load Case B the table pressure multiplied by the projected frontal area of the screen enclosure is the total drag force, including drag on screen surfaces parallel
to the wind, which must be transmitted to the ground. Use Load Case A for members directly supporting the screen surface perpendicular to the wind. Load Case B
loads shall be applied only to structural members which carry wind loads from more than one surface.
f. The roof structure shall be analyzed for the pressure given occurring both upward and downward.
TABLE AH107.4(2)
HEIGHT ADJUSTMENT FACTORS
MEAN
EXPOSURE
Roof Height (ft)
B
C
15
1
0.86
20
1
0.92
25
1
0.96
30
1
1.00
35
1.05
1.03
40
1.09
1.06
45
1.12
1.09
50
1.16
1.11
55
1.19
1.14
60
1.22
1.16
For SI: 1 foot = 304.8 mm.
616
2010 CALIFORNIA RESIDENTIAL CODE
a recorded final map or parcel map. See also Chapter 11.4.80: Condominium
Conversions.
Con'. ming Building:
❑ In '�- residential "R" zones, a conforming building is one wh' sr gully meets
the uirements of the State Housing Act and the . ` ornia Building
Code �•z they pertain to residential buildings and , ich building fully
conforms the requirements of this chapter wit , 'espect to the district
and zone in ,, ich it is located; and
❑ In the commerci "C' and manufacturing "M" ones, a conforming building
is one which fully c forms to the structur design, building materials and
their assembly as pr -. ribed for comm ial or industrial buildings by the
California Building Co and whi� building fully conforms to the
requirements of this chap\ with r :'•ect to the district and zone in which
it is located.
Construction Cost: the total cost ,,
r uire.to construct, rebuild, repair, remodel or
make an addition to an exis '• buildin: including all permanent work and
permanent equipment, exclu. }g landscaping.
Convalescent Hos ee: Skilled Nursing Facili
Convenience Mai t: any accessory use to automobi ervice station for any
retail sales of ,,4od, beverages and small convenience i - . s primarily for off -
premises c•.,� sumption and typically found in establishment \. ith long or late
hours of : peration and a relatively small building. Arcade'„ achines are
prohib;. =d in a convenience market. See Section 11.4.05.035: utomobile
Se f e Stations in Chapter 11.4.05: Standards for Specific Uses.:
ourt: any portion of the interior of a lot or building site which is wholl ' °,.r
partially surrounded by buildings and which is not a required yard or open space.
Courtyard: an extent of open ground enclosed by walls and adjacent residential
building.
Covered Patio: a roofed structure located between a dwelling and a side or rear
property line that shelters an outdoor area. These structures are either attached
to or detached from a primary dwelling on the site.
City of Seal Beach
Title 11 - Part VI - page 15
Municipal Code
Ord. No. 1598
October 11, 2010