HomeMy WebLinkAboutAPPROVED DESIGN PRESSURESPer ASCE 746 Part i and FBC (2020) for Retrofitting in Accordance with Formal Interpretation #24
For Detached One-and Two family dwellings and Multiple Si ngl e-Fa mily Dwellings (Tow n h ou ses) with Mean Roof Height S 30 feet
Wind 170 mph (3-second gusty J E_xposu re C' * / Itd = 0.85 / Kzt =1,Q /Pressures are in PSF / Not for use in coastal (Ex pos u re V iareas)
Using Allowable Stress Design methodology (P = 0.6w) j *+ Exposure C or D shall be determined according to ASCU 7-15 Section 263 (Exposure Categories]
Roof and Wall Zone Chart Diagrams
Wall Pressure chart
Flat Rood Uplift Chart
Gable Roof Uplift Chart
Hip Roof Uplift Chart
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Instructions on how to use these Charts: determine Mean Roof Height, h , which is tap of roof for flat roofs or the mean roof height for pitched roofs. Find your least
horizontal dimension for your building, not including a overhang if it occurs. Calculate the value of, a, = 109'0 of least horizontal dimension or Q.4*h, whichever is
smaller, out not less than either 496 of least horizontal dimension or 3 feet. If your roof height is less than 30 feet! but not exactly 15., 20., or 25 feet,, you will need to go
to the next higher roof height. If your Mean Fovf Height is higher than 30 feet, these charts do not apply. Review the diagram which illustrate the wolf and roof zones
and determine the wind zone in which the component is located. Determine the tributary area of the component. If the tributary area falls in between values, use the
value of the smaller tributary area. Select the positive and negative wind pressures corresponding to the wall or roof zone where your component is located, boar
pressures shown are for the most common door sites and are worst case for heights <= 30 Feet.
Wail Pres5umFor All Roof Types
Garage/Door Pressures
Mean Roof Hei t 15 Ft)
20 Ft
<= 30 Ft
Tributary Area 10
0
35
50
500
la
24
35
50
100
500
Effective Wind Area
Positive
Negative
Wall Positive Pressure 38.E
3b.
34.914.!32.3
28.3
40.3
38.5
37.E
36.1
343
30.1
Width
Height
Zone 4 Negative Pressure -41.2
-3 .5
-38.1
-3 5
-31.5
-43.7
-41.9
AO-5
-39.5
-37.7
-33.5
8
8
38.6
-48.2
Zone 5 Negative Pressure -5D.8
-47.4
-44.6
-42.9
-395
-33�.5
-54.0
-50.4
-47.4
-4�.0
-41.9
-33.5
10
10
37.4
-45.7
Mean Roof Het ht 25 Ft
30 Ft
14
14
35.4
-41.8
Tributary Area 10 20 35 50 tan 500
IO 20 35 50 100 500
9
7
38.7
-4$.3
43.9
41.9
40.3
39.3
37.3
32.8
lfi
7
37.0
-45.0
Wall Positive Pressure 42.3 40.4 38.8 37.8 35.9 31.5
zone 4 Negative Pressure -45.8 -43.9 -42.4 -41.4 -39.51 -35.1
1-47.8
-47.6
-45.7
-44.1
-43.1
-41.1
-36,5
3
7
41.8
-54.6
Zone 5 Me alive Pressure -56.6 -52.8 -49.7 -43.9 -35.1
-55.8
-54.7
-52.7
-49.5
-45.7
-36.5
fi
7
39.8
-50.6
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