Page 901 - 2018_IRC

APPENDIX H

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AH106.3 Screen enclosures. Screen enclosures shall com- R506, be not less than 3 / inches (89 mm) thick and the col-
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ply with Sections AH106.3.1 and AH106.3.2. umns shall not support loads in excess of 750 pounds (3.36
AH106.3.1 Thickness. Actual wall thickness of extruded kN) per column.
aluminum members shall be not less than 0.040 inch (1.02
mm).
AH106.3.2 Density. Screen density shall be not more than
TABLE AH106.4(2)
20 threads per inch by 20 threads per inch mesh. ADJUSTMENT FACTOR FOR
AH106.4 Design. The structural design of screen enclosures BUILDING HEIGHT AND EXPOSURE
shall comply with Sections AH106.4.1 through AH106.4.3. MEAN ROOF EXPOSURE
HEIGHT
AH106.4.1 Wind load. Structural members supporting (feet) B C D
screen enclosures shall be designed to support the mini- 15 1.00 1.21 1.47
mum wind loads given in Tables AH106.4(1) and
AH106.4(2) for the ultimate design wind speed, V , deter- 20 1.00 1.29 1.55
ult
mined from Figure AH106.4.1. Where any value is less 25 1.00 1.35 1.61
than 10 pounds per square foot (psf) (0.479 kN/m ) use 10 30 1.00 1.40 1.66
2
2
pounds per square foot (0.479 kN/m ). 35 1.05 1.45 1.70
AH106.4.2 Deflection limit. For members supporting 40 1.09 1.49 1.74
screen surfaces only, the total load deflection shall not
exceed l/60. Screen surfaces shall be permitted to include 45 1.12 1.53 1.78
not more than 25-percent solid flexible finishes. 50 1.16 1.56 1.81
AH106.4.3 Roof live load. The roof live load shall be not 55 1.19 1.59 1.84
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less than 10 psf (0.479 kN/m ). 60 1.22 1.62 1.87
AH106.5 Footings. In areas with a frost line depth of zero, For SI: 1 foot = 304.8 mm.
screen enclosures supported on a concrete slab-on-grade
without footings shall conform to the provisions of Section

TABLE AH106.4(1)
DESIGN WIND PRESSURES FOR SCREEN ENCLOSURE FRAMING a, b, e, f, g, h
ULTIMATE DESIGN WIND SPEED, V ult
(mph)
LOAD WALL
CASE 100 105 110 120 130 140 150 160 170 180
Exposure Category B Design Pressure (psf)
A c Windward and leeward walls (flow thru) and 6 7 8 9 11 13 14 16 18 21
windward wall (nonflow thru) L/W = 0-1
A c Windward and leeward walls (flow thru) and 7 8 9 1 1 1 2 1 4 1 6 1 9 2 1 2 4
windward wall (nonflow thru) L/W = 2
B d W i n d w a r d : N o n g a b l e r o o f 9 1 0 1 1 1 3 1 5 1 8 2 1 2 3 2 6 3 0
B d Windward: Gable roof 11 13 14 16 19 22 26 29 33 37
ROOF
All e R o o f - s c r e e n 2 3 3 3 4 4 5 6 7 7
All e R o o f - s o l i d 7 8 8 1 0 1 2 1 3 1 5 1 8 2 0 2 2
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.
a. Design pressure shall be not less than 10 psf in accordance with Section AH106.4.1.
b. 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(2).
c. 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.
d. 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.
e. The roof structure shall be analyzed for the pressure given occurring both upward and downward.
f. 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.
g. 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.
h. Linear interpolation shall be permitted.

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