Laserfiche WebLink
SolarMount Unirac Code-Compliant Installation Manual :i:UN I RAC <br />Part I. Procedure to Determine the Design Wind Load <br />[1.1.] Using the Simplified Method - ASCE 7-05 <br />The procedure to determine Design Wind Load is specified <br />by the American Society of Civil Engineers and referenced in <br />the International Building Code 2009. For purposes of this <br />document, the values, equations and procedures used in this <br />document reference ASCE 7-05, Minimum Design Loads for <br />Buildings and Other Structures. Please refer to ASCE 7-05 if <br />you have any questions about the definitions orprocedures <br />presented in this manual. Unirac uses Method 1, the <br />Simplified Method, for calculating the Design Wind Load for <br />pressures on components and cladding in this document. <br />The method described in this document is valid for flush, no <br />tilt, SolarMount Series applications on either roofs or walls. <br />Flush is defined as panels parallel to the surface (or with no <br />more than 3" difference between ends of assembly) with no <br />more than 10" space between the roof surface, and the bottom <br />of the PV panels. <br />This method is not approved for open structure calculations. <br />Applications ofthese procedures is subject to thefollowing <br />ASCE 7-05 limitations: <br />1. The building height must be less than 60 feet, h < 60. See <br />note for determining h in the next section. For installations <br />on structures greater than 60 feet, contact your local Unirac <br />Distributor. <br />2. The building must be enclosed, not an open or partially <br />enclosed structure, for example a carport. <br />3. The building is regular shaped with no unusual geometrical <br />irregularity in spatial form, for example a geodesic dome. <br />4. The building is not in an extreme geographic location such <br />as a narrow canyon or steep cliff. <br />5. The building has a flat or gable roof with a pitch less than 45 <br />degrees or a hip roof with a pitch less than 27 degrees. <br />6. If your installation does not conform to these requirements <br />please contact your local Unirac distributor or a local <br />professional engineer. <br />If your installation is outside the United States or does not <br />meet all of these limitations, consult a local professional <br />engineer or your local building authority. Consult ASCE 7-05 <br />for more clarification on the use of Method I. Lower design <br />wind loads may be obtained by applying Method II from ASCE <br />7-05. Consult with a licensed engineer if you want to use <br />Method II procedures. <br />The equation for determining the Design Wind Load for <br />components and cladding is: <br />pnet (psf) = AKzd pnet3O <br />pnet (Pd) = Design Wind Load <br />X = adjustmentfactorfor building height and exposure category <br />Kzt = Topographic Factor at mean roof height, h (ft) <br />I = Importance Factor <br />pnet30 (Psf) = net designwind pressurefor Exposure B, at height = <br />30feet, I = 1.0 <br />You will also need to know the following information: <br />Basic Wind Speed = V (mph), the largest 3 second gust of wind in <br />the last 50 years. <br />h (ft) = total roof heightfor.flat roof buildings or mean roofheight <br />for pitched roof buildings <br />RoofPitch (degrees) <br />This manual will help you determine: <br />Effective Wind Area (sf) = minimum total continuous area of <br />modules being installed (Step 2) <br />Roof Zone = the area of the roof you are installing the pv system <br />according to Step 3. <br />RoofZone Dimension = a (ft) (Step 3) <br />Exposure Category (Step 6) <br />[1.2.] Procedure to Calculate Total Design Wind <br />The procedure for determining the Design Wind Load can be <br />broken into steps that include looking up several values in <br />different tables. Table 5 has been provided as a worksheet for <br />the following 9 steps (page 8) <br />Step 1: Determine Basic Wind Speed, V (mph) <br />Determine the Basic Wind Speed, VOMph) by consulting your <br />local building department or locating your installation on the <br />maps in Figure 1, page 4. <br />Step 2: Determining Effective Wind Area <br />Determine the smallest area of continuous modules you will <br />be installing. This is the smallest area tributary (contributing <br />load) to a support or to a simple-span of rail. That area is the <br />Effective Wind Area, the total area of the fewest number of <br />modules on a run of rails. If the smallest area of continuous <br />modules exceeds 100 sq ft, use 100 sq ft (See Table 2). If less, <br />round down to values available in Table 2. <br />0 <br />P.Ke <br />3