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Home My WebLink AboutLA216091 - APPROVED - Daniel Cunningham Engineering Letter Flat___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com To: Blue Raven Solar 1403 North Research Way, Building J Orem, UT. 84097 Subject: Certification Letter Cunningham Residence 17115 Hannibal Ct Lakeville, MN. 55044 To Whom It May Concern, Design Criteria: භ Applicable Codes = 2018 IBC/IRC, ASCE 7-16 භ Roof Dead Load = 7 psf (MP1) භ Roof Live Load = 20 psf භ Wind Speed = 115 mph (Vult), Exposure C භ භ Sincerely, John Calvert, P.E. Project Engineer The scope of this report is strictly limited to an evaluation of the fastener attachment, underlying framing and supporting structure only. The attachment's to the existing structure are required to be in a staggered pattern to ensure proper distribution of loading. All panels, racking and hardware shall be installed per manufacturer specifications and within specified design limitations. All waterproofing shall be provided by the manufacturer. Domus Structural Engineering assumes no responsibility for misuse or improper installation of the solar PV panels or racking. Please contact me with any further questions or concerns regarding this project. Note: Seismic check is not required since Ss<.4g and Seismic Design Category (SDC) < B Attachment: 1 - 5/16 dia. lag screw with 2.5 inch min. embedment depth, at spacing shown above. I hereby certify that this plan, specification or report was prepared by me or under my direct supervision and that I am a duly Licensed Professional Engineer under the laws of the State of Minnesota.John A. Calvert, License No. 52823 Expiration Date: 30-June-2024 August 3, 2023 The roof structure of (MP1) consists of composition shingle on roof plywood that is supported by pre-manufactured trusses that are spaced at @ 24"o.c.. The top chords, sloped at 40 degrees, are 2x4 sections, the bottom chords are 2x4 sections and the web members are 2x4 sections. The truss members are connected by steel gusset plates. The max unsupported projected horizontal top chord span is approximately 6'-6''. The existing roof framing system of (MP1) is judged to be adequate to withstand the loading imposed by the installation of the solar panels. No reinforcement is necessary. Ground Snow Load = 50 psf - Roof Snow Load = 35 psf The spacing of the solar standoffs should be kept at 48" o.c. for landscape and 24" o.c. for portrait orientation, with a staggered pattern to ensure proper distribution of loads. A jobsite observation of the condition of the existing framing system was performed by an audit team of Blue Raven Solar as a request from Domus Structural Engineering. All review is based on these observations and the design criteria listed below and only deemed valid if provided information is true and accurate. On the above referenced project, the roof structural framing has been reviewed for additional loading due to the installation of the solar PV addition to the roof. The structural review only applies to the section of the roof that is directly supporting the solar PV system and its supporting elements. The observed roof framing is described below. If field conditions differ, contractor to notify engineer prior to starting construction. Cunningham Lakeville MN 1 Digitally signed by John A. Calvert Date: 2023.08.03 14:11:58 -06'00' Concept Approval ONLYSubject to Field Inspection Inspector Date 2020 MN Bldg Code 08/04/2023dpfannenstein Please provide a City Approved Plan and Permit Card on site accessible for Inspectors until final inspection ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com 50.0 psf (ASCE7 - Eq 7-1) 1 (ASCE7 - Table 7-2) 1 (ASCE7 - Table 7-3) 1 35.0 psf (ASCE7 - Eq 7-2) 1 35.0 psf 3.92 psf 3.0 psf 2.00 ft 6.08 ft 12.17 sft 37 lb 4.00 2.00 0.73 0.00 (Ceiling Not Vaulted) 0.27 7.0 psf 9.1 psf PV Dead Load = 3 psf (Per Blue Raven Solar) DL Adjusted to 40 Degree Slope Point Loads of Standoffs Miscellaneous Vaulted Ceiling Total Roof DL (MP1) Roof Live Load = 20 psf Roof Plywood Roof Dead Load (MP1) Composition Shingle Note: Roof live load is removed in area's covered by PV array. Roof Snow Load Calculations pg = Ground Snow Load = Ce = Exposure Factor = pf = 0.7 Ce Ct I pg Ct = Thermal Factor = I = Importance Factor = Cs = Slope Factor = Standoff Tributary Area = ps = Cspf ps = Sloped Roof Snow Load = pf = Flat Roof Snow Load = DL Adjusted to 40 Degree Slope Gravity Loading PV System Weight Weight of PV System (Per Blue Raven Solar) X Standoff Spacing = Y Standoff Spacing = Note: PV standoffs are staggered to ensure proper distribution of loading 2x4 Top Chords @ 24"o.c. Cunningham Lakeville MN 2 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com 115 mph C Gable Roof 40 degrees 20 ft 21.3 ft 0 ft (Eq. 26.10-1) 0.90 (Table 30.3-1) 1.00 (Fig. 26.8-1) 0.85 (Table 26.6-1) 1.00 115 mph (Fig. 26.5-1A) II (Table 1.5-1) qh = 25.95 Zone 1 Zone 2 Zone 3 Positive ya =0.77 0.80 0.80 0.77 GCp =-1.71 -2.00 -2.89 0.87 (Fig. 30.3) Uplift Pressure =-34.3 psf -41.5 psf -60.0 psf 17.3 psf (Eq. 29.4-7) ASD Uplift Pressure =-20.6 psf -24.9 psf -36.0 psf 10.4 psf X Standoff Spacing = 2.00 2.00 1.33 Y Standoff Spacing = 6.08 3.04166667 3.04166667 Tributary Area = 12.17 6.08 4.06 Dead Load on attachment = 37 lb 18 lb 12 lb Footing Uplift (0.6D+0.6W) = -229 lb -141 lb -139 lb Zone 1 Zone 2 Zone 3 Positive ya =0.75 0.80 0.80 0.75 GCp =-1.65 -2.00 -2.83 0.84 (Fig. 30.3) Uplift Pressure =-32.2 psf -41.5 psf -58.7 psf 16.4 psf (Eq. 29.4-7) ASD Uplift Pressure (0.6W)=-19.3 psf -24.9 psf -35.2 psf 9.8 psf X Standoff Spacing = 4.00 4.00 2.67 Y Standoff Spacing = 3.50 1.75 1.75 Tributary Area = 14.00 7.00 4.67 Dead Load on attachment = 42.00 21.00 14.00 Footing Uplift (0.6D+0.6W) = -246 lb -162 lb -156 lb -246 lb 450 lb Therefore, OK Fastener =1 - 5/16" dia. lag Number of Fasteners = 1 Embedment Depth = 2.5 Pullout Capacity Per Inch = 250 lb Fastener Capacity = 625 lb w/ F.S. of 1.5 & DOL of 1.6= 667 lb Therefore, OK Wind Calculations Maximum Design Uplift = Design Wind Pressure Calculations qh = 0.00256 * Kz * Kzt * Kd * Ke * V^2 Kz (Exposure Coefficient) = Kzt (topographic factor) = Wind Speed Exposure Category Roof Shape Roof Slope Effective Wind Area Per ASCE 7-16 Components and Cladding Input Variables Fastener Capacity Check Mean Roof Height Ground Elevation Kd (Wind Directionality Factor) = 667.2 lb capacity > 246 lb demand Ke (Ground Elevation Factor) = V (Design Wind Speed) = Risk Category = Standoff Uplift Calculations-Portrait Standoff Uplift Calculations-Landscape Standoff Uplift Check Standoff Uplift Capacity = 450 lb capacity > 246 lb demand Cunningham Lakeville MN 3 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com (MP1)PASS Dead Load 9.1 psf PV Load 3.9 psf Snow Load 35.0 psf Governing Load Combo = DL + SL Total Load 48.1 psf Fb (psi) = f'b x Cd x Cf x Cr (NDS Table 4.3.1) 1650 x 1.15 x 1 x 1.15 Allowed Bending Stress = 2182.1 psi (wL^2) / 8 = 507.5711 ft# = 6090.854 in# Actual Bending Stress = (Maximum Moment) / S = 1988.9 psi L/180 (E = 1500000 psi Per NDS) = 0.433 in Deflection Criteria Based on = (w*L^4) / (185*E*I) = = L/390 > L/180 Therefore OK Allowed Deflection (Live Load) =L/240 0.325 in (w*L^4) / (185*E*I) L/535 > L/240 Therefore OK Member Area = Fv (psi) = 135 psi (NDS Table 4A) Allowed Shear = Fv * A = Max Shear (V) = w * L / 2 = 312 lb Check Bending Stress (True Dimensions) Continuous Span 0.200 in 0.146 in Member Properties Member Size 2x4 S (in^3) 3.06 1650Fb/1.5E Member Spacing @ 24"o.c. Maximum Moment = Check Deflection I (in^4) 5.36 Lumber Sp/Gr Actual Deflection (Live Load) = Allowed Deflection (Total Load) = Actual Deflection (Total Load) = Allowed > Actual -- 91.2% Stressed -- Therefore, OK 709 lb Allowed > Actual -- 44.1% Stressed -- Therefore, OK 5.3 in^2 Check Shear w = 96 plf 2x4 Top Chords @ 24"o.c. Member Span = 6' - 6" Framing Check Cunningham Lakeville MN 4 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com Appendix A: General Notes GENERAL Ɣ The contractor shall verify all dimensions, property setbacks, AHJ/HOA CC&R's, elevations and site conditions before starting work and shall notify Domus Structural Engineering, LLC of any discrepancies. Ɣ All report conclusions represent Domus Structural Engineering, LLC's best professional judgment based upon industry standards. Ɣ Resolve any conflicts on the drawings with Domus Structural Engineering, LLC before proceeding with construction. Ɣ The design criteria used for this project & listed on the first page of the report is based on the engineers best judgement and/or provided by the ATC council. AHJ specific requests may differ. Please contact our team if the design criteria needs to be modified. Ɣ A site visit was not physically conducted by Domus Structural Engineering, LLC. The accompanying calculations and certification are provided with the understanding that the site building and construction standards meet an acceptable level of industry standards. It shall be the contractors responsibility to identify any irregularities such as inconsistent framing conditions, water damage, fire damage, cracked, split or noticeably deflecting framing members. Ɣ Domus Structural Engineering, LLC is not responsible for enforcing safety measures or regulations. The contractor shall design, construct, and maintain all safety devices including shoring and bracing, and shall be solely responsible for conforming to all local, state and federal safety and health standards, laws and regulations. The contractor shall take necessary precautions to maintain and insure the integrity of the structure during construction. If a lawsuit is filed by one of the contractor's or subcontractor's employees, or any one else, the contractor will indemnify, defend and hold the owner and Domus Structural Engineering, LLC harmless of any and all such claims. Ɣ Any and all waterproofing shall be provided by the contractor. Domus Structural Engineering, LLC is not responsible for waterproofing. Ɣ All hardware shall be installed per manufacturer specifications and within specified design limitations. Domus Structural Engineering, LLC assumes no responsibility for incorrectly installed hardware or hardware installed outside of the manfacturer specifications. USER RELIANCE Ɣ Domus Structural Engineering, LLC was engaged by Blue Raven Solar (Client) to perform this assessment. This report and the information therein, are for the exclusive use of the Client. This report has no other purpose and shall not be relied upon, or used, by any other person or entity without the written consent of Dous Structural Engineering, LLC. Third parties that obtain this report, or the information within shall have no rights of recourse or recovery against Domus Structural Engineering, LLC, it’s officers or employees. ROOF MOUNTED ARRAYS Ɣ If an analysis of a supporting stucture is included in our scope of work, the structural assessment only applies to the section of the roof that is directly supporting the proposed solar PV system. Ɣ No structural members can be cut for conduit, etc., unless specifically shown. Obtain prior written approval for installation of any additional conduit, etc. Ɣ It is assumed that a standard quality of construction care was used to construct the original building. It shall be the contractors responsibility to field verify any and all framing member supporting the proposed PV array are in adequate condition. The contractor shall field inspect for sub-standard construction means, signs of dry rot, mold, fire damage, etc. and notify engineer if any compromised material is found on site prior to starting construction. Ɣ It is assumed that there have been no additional loads (HVAC or MEP equipment, additional layers of roofing, etc) added to the building over the course of the structures histroy. The contractor and/or client shall verify this with the property owner and notify Domus Structural Engineering, LLC if additional load has been added to the structure already. Ɣ Flexible utility connections must be used at any building seismic joint. Ɣ Care should be taken to ensure that PV arrays do not preclude drainage of rain water. Ɣ Unless otherwise noted, construction material shall be evenly distributed if placed on framed floors or roofs. Loads shall not exceed the allowable loading for the supporting members and their connections. Ɣ All lags or wood screws at the roof shall be stainless steel and installed withing the middle 1/3 of the dimensional width of the framing members. Ɣ All fasteners shall be a minimum of 6" away from any truss panel or hinge joints, truss plates and/or member ends. Field verify location of fasteners prior to starting construction. All fasteners shall be pre-drilled to avoid splitting existing lumber. Ɣ Domus Structural Engineering, LLC is not responsible for downslope effects of snow shedding or sliding off of the PV array nor any damage to downslope decks, roofs, walkways, landscaping, automobiles, pets, people, etc.. If snow guards are requested by the customer, notify Domus Structural Engineering, LLC. Cunningham Lakeville MN 5