(The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordinance.)
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.
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 the following:
1. Insect screening;
2. Approved translucent or transparent plastic not more than 0.125 inch (3.2 mm) in thickness;
4. Any combination of the foregoing.
Exterior openings required for light and ventilation shall be permitted to open into a patio structure conforming to Section AH101, provided that the patio structure shall be unenclosed if such openings are serving as emergency 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 R311 of this code.
Patio covers shall be designed and constructed 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 Section R301.2.1.
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, 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.
Screen enclosures in hurricane-prone regions shall be in accordance with the provisions of this Section.
Screen enclosures shall have a ceiling height of not less than 7 feet (2134 mm).
The following word and term shall, for the purposes of this appendix, have the meaning shown herein.
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.
Actual wall thickness of extruded aluminum members shall be not less than 0.040 inch (1.02 mm).
Screen density shall be a maximum of 20 threads per inch by 20 threads per inch mesh.
The structural design of screen enclosures shall comply with Sections AH106.4.1 through AH106.4.4.
DESIGN WIND PRESSURES FOR ALUMINUM SCREEN ENCLOSURE FRAMING WITH AN IMPORTANCE FACTOR OF 0.77a, b, c
|WALL||Basic Wind Speed (mph)|
|Exposure Category Design Pressure (psf)|
|Ad||Windward and leeward walls (flow thru) and windward wall (nonflow 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 (nonflow thru) L/W = 2||13||9||16||11||19||14||22||16||26||18||30||21|
|Be||Windward: Nongable 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|
For SI: 1 mile per hour = 0.44 m/s, 1 pound per square foot = 0.0479 kPa, 1 foot = 304.8 mm.
a. Values have been reduced for 0.77 importance factor in accordance with Section AH106.4.3.
b. Minimum design pressure shall be 10 psf in accordance with Section AH106.4.1.
c. Loads are applicable to screen enclosures with a mean 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 AH106.4(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 nonflow 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.
HEIGHT ADJUSTMENT FACTORS
|Roof Height (feet)||B||C|
For SI: 1 foot = 304.8 mm.
For members supporting screen surfaces only, the total load deflection shall not exceed l/60. Screen surfaces shall be permitted to include a maximum of 25-percent solid flexible finishes.
The wind factor for screen enclosures shall be 0.77 in accordance with Section 6.5.5 of ASCE 7.
The minimum roof live load shall be 10 psf (0.479 kN/m2).
In areas with a frost line depth of 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 31/2 inches (89 mm) thick and the columns do not support loads in excess of 750 pounds (3.36 kN) per column.