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PPurelight <br /> Lag Screw Calculation <br /> This calculation justifies the connection of the solar panels to existing roof members, by <br /> showing the connection capacity is equal to or greater than the uplift force demands. <br /> Connection Demand <br /> Spacing perpendicular to rail 32.5 in 1/2 panel length <br /> Roof Angle 26 degrees <br /> Wind Speed 110 mph <br /> Exposure Coefficient, KZ 0.88 <br /> Topographic Factor, K, 1 <br /> Directionality Factor, Kd 0.85 <br /> Elevation Factor, Ke 1.00 <br /> Velocity Pressure, qZ 23.1 psf <br /> Prying Coefficient 1 <br /> Zone 1 Zone 2r Zone 3 <br /> Spacing parallel to rail 48 48 48 in Max spacing <br /> Effective Wind Area on each connection 10.8 10.8 10.8 ft 2 <br /> GCp(max) 1.90 1.97 1.97 <br /> Exposed Panels? (YE= 1.5) No No No <br /> Pressure Equalization Factor,ya 0.79 0.79 0.79 <br /> Uplift Force 34.5 35.9 35.9 psf <br /> Max. Uplift Force/Connection (0.6 WL) 224.0 233.1 233.1 lbs <br /> Solar Dead Load (0.6 DL) 17.9 17.9 17.9 lbs <br /> Max. Uplift Force (0.6 WL-0.6 DL) 206.2 215.2 215.2 lbs <br /> Connection Capacity <br /> Fastener Type Lag Screw <br /> Fastener Diameter 0.3125 in <br /> Embedment Length, min 2.5 in <br /> Lumber Species &Grade DFL#2 (Assumed) <br /> Lumber Specific Gravity 0.5 <br /> Nominal Withdrawal Capacity,W 665.0 lbs NDS 12.2-1 <br /> #of Screws 1 <br /> Load Duration Factor, CD 1.6 <br /> Adjusted Withdrawal Capacity,W' 1064.0 lbs <br /> Compare Adjusted Withdrawal Capacity to ASD Factored Demand <br /> Zone 1 Zone 2r Zone 3 <br /> O.K. O.K. O.K. <br />