The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordinance.
User note:
About this appendix: Appendix AH relaxes certain provisions contained in the body of the code as related to patio covers, including those regarding: permitted uses; exterior wall insect screens; glazing and translucent or transparent plastic; light, ventilation and emergency egress; height; structural design loads; and footings. This appendix also includes provisions that are specifically applicable to hurricane-prone regions.
Patio covers shall conform to the requirements of Sections AH101 through AH106.
Patio covers detached from or attached to dwelling units shall be used only for recreational, outdoor living purposes, and not as carports, garages, storage rooms or habitable rooms.
The following word and term shall, for the purposes of this appendix, have the meaning shown herein.
PATIO COVER. A structure with open or glazed walls that is used for recreational, outdoor living purposes associated with a dwelling unit.
Enclosure walls shall be permitted to be of any configuration, provided that the open or glazed area of the longer wall and one additional wall is not less than 65 percent of the area below 6 feet 8 inches (2032 mm) of each wall, measured from the floor. Openings shall be enclosed with any of the following:
- Insect screening.
- Approved translucent or transparent plastic not more than 0.125 inch (3.2 mm) in thickness.
- Glass conforming to the provisions of Section R308.
- Any combination of the foregoing.
Exterior openings required for light and ventilation into a patio structure conforming to Section AH101 shall be unenclosed where such openings serve 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.
Patio covers are limited to one-story structures not exceeding 12 feet (3657 mm) in height.
Patio covers shall be designed and constructed to sustain, within the stress limits of this code, all dead loads plus a vertical live load of not less than 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, for patio covers supported on a slab-on-grade without footings, the slab shall conform to the provisions of Section R506, shall be not less than 3.5 inches (89 mm) thick and the columns shall 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 not be considered habitable spaces.
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.
Screen enclosures shall comply with Sections AH106.3.1 and AH106.3.2.
Actual wall thickness of extruded aluminum members shall be not less than 0.040 inch (1.02 mm).
Screen density shall be not more than 20 threads per inch by 20 threads per inch mesh.
The structural design of screen enclosures shall comply with Sections AH106.4.1 through AH106.4.3.
Structural members supporting screen enclosures shall be designed to support the minimum wind loads given in Tables AH106.4.1(1) and AH106.4.1(2) for the ultimate design wind speed, Vult, determined from Figure AH106.4.1. Where any value is less than 10 pounds per square foot (psf) (0.479 kN/m2) use 10 pounds per square foot (0.479 kN/m2).
For SI: 1 foot = 304.8 mm, 1 mph = 0.447 m/s.
Notes:
- Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 feet above ground for Exposure C category.
- Linear interpolation between contours is permitted.
- Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
- Mountainous terrain, gorges, ocean promontories and special wind regions shall be examined for unusual wind conditions.
- Wind speeds correspond to approximately a 7-percent probability of exceedence in 50 years (Annual Exceedence Probability = 0.00143, MRI = 700 years).
FIGURE AH106.4.1
ULTIMATE DESIGN WIND SPEEDS FOR PATIO COVERS AND SCREEN ENCLOSURES
DESIGN WIND PRESSURES FOR SCREEN ENCLOSURE FRAMINGa, b, e, f, g, h
| LOAD CASE | WALL | ULTIMATE DESIGN WIND SPEED, Vult (mph) | |||||||||||
| 90 | 95 | 100 | 105 | 110 | 120 | 130 | 140 | 150 | 160 | 170 | 180 | ||
| Exposure Category B Design Pressure (psf) | |||||||||||||
|
Ac
|
Windward and leeward walls (flow thru) and windward wall (nonflow thru) L/W = 0-1 | 5 | 6 | 6 | 7 | 8 | 9 | 11 | 13 | 14 | 16 | 18 | 21 |
|
Ac
|
Windward and leeward walls (flow thru) and windward wall (nonflow thru) L/W = 2 | 6 | 7 | 7 | 8 | 9 | 11 | 12 | 14 | 16 | 19 | 21 | 24 |
|
Bd
|
Windward: Nongable roof | 7 | 8 | 9 | 10 | 11 | 13 | 15 | 18 | 21 | 23 | 26 | 30 |
|
Bd
|
Windward: Gable roof | 10 | 10 | 11 | 13 | 14 | 16 | 19 | 22 | 26 | 29 | 33 | 37 |
| ROOF | |||||||||||||
|
Alle
|
Roof-screen | 2 | 2 | 2 | 3 | 3 | 3 | 4 | 4 | 5 | 6 | 7 | 7 |
|
Alle
|
Roof-solid | 6 | 6 | 7 | 8 | 8 | 10 | 12 | 13 | 15 | 18 | 20 | 22 |
For SI: 1 inch = 25.4 mm, 1 mile per hour = 0.44 m/s, 1 pound per square foot = 0.0479 kPa, 1 foot = 304.8 mm.
- Design pressure shall be not less than 10 psf in accordance with Section AH106.4.1.
- Loads are applicable to screen enclosures with a mean roof height of 30 feet or less in Exposure B. For screen enclosures of different heights or exposure, the pressures given shall be adjusted by multiplying the table pressure by the adjustment factor given in Table AH106.4.1(2).
- 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 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.
- 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, that 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 that carry wind loads from more than one surface.
- The roof structure shall be analyzed for the pressure given occurring both upward and downward.
- Table pressures are MWFRS loads. The design of solid roof panels and their attachments shall be based on component and cladding loads for enclosed or partially enclosed structures as appropriate.
- Table pressures apply to 20-inch by 20-inch by 0.013-inch mesh screen. For 18-inch by 14-inch by 0.013-inch mesh screen, pressures on screen surfaces shall be permitted to be multiplied by 0.88. For screen densities greater than 20 inches by 20 inches by 0.013 inch, pressures for enclosed buildings shall be used.
- Linear interpolation shall be permitted.
ADJUSTMENT FACTOR FOR BUILDING HEIGHT AND EXPOSURE
| MEAN ROOF HEIGHT (feet) | EXPOSURE | ||
| B | C | D | |
| 15 | 1.00 | 1.21 | 1.47 |
| 20 | 1.00 | 1.29 | 1.55 |
| 25 | 1.00 | 1.35 | 1.61 |
| 30 | 1.00 | 1.40 | 1.66 |
| 35 | 1.05 | 1.45 | 1.70 |
| 40 | 1.09 | 1.49 | 1.74 |
| 45 | 1.12 | 1.53 | 1.78 |
| 50 | 1.16 | 1.56 | 1.81 |
| 55 | 1.19 | 1.59 | 1.84 |
| 60 | 1.22 | 1.62 | 1.87 |
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 not more than 25-percent solid flexible finishes.
The roof live load shall be not less than 10 psf (0.479 kN/m2).
In areas with a frost line depth of zero, screen enclosures supported on a concrete slab-on-grade without footings shall conform to the provisions of Section R506, be not less than 31/2 inches (89 mm) thick and the columns shall not support loads in excess of 750 pounds (3.36 kN) per column.