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Structural Letter - Ashton, Joseph - Leeds, MA - 10421531___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com To: RGS Energy 420 Woodland Ave. Unit A Bloomfield, CT. 06002 Subject: Certification Letter Ashton Residence 1 Bernache St Leeds, MA. 01053 To Whom It May Concern, 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. March 18, 2019 The roof structure of (Roof 1) consists of composition shingle on roof plywood that is supported by 2x8 rafters @ 24"o.c., paired  with nominal 2x8 ceiling joists @ 24"o.c.. The rafters are suported by veritcal struts which transfer gravity loads to the ceiling  joists below. The rafters have a max projected horizontal span of 8'‐6", with a slope of 37 degrees. The rafters are connected at  the ridge to a ridge board and are supported at the eave by a load bearing wall.  The roof structure of (Roof 2) consists of composition shingle on roof plywood that is supported by nominal 2x6 rafters @ 24"o.c.  paired with 2x6 ceiling joists @ 48"o.c.. The rafters have a max projected horizontal span of 13'‐0", with a slope of 16 degrees.  The rafters are connected at the ridge to a ridge board and are supported at the eave by a load bearing wall.  The existing roof framing system of (Roof 1) is judged to be adequate to withstand the loading imposed by the installation of the  solar panels. No reinforcement is necessary.  The existing roof framing system of (Roof 2) is judged to be inadequate to withstand the loading imposed by the installation of the solar panels. Structural reinforcement is required.  Sister upgrade is required for (Roof 2) on all rafters that directly support solar  PV. Stitch new 2x8 DF#2 (min) to existing member with Simpson SDW 22300 screws @ 16''o.c. or 10d nails @ 6''o.c.. Lap as  needed with 4'‐0'' lap per attached detail. The spacing of the solar standoffs should be kept at 48" o.c. for landscape and 48" 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 RGS Energy 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. Ashton Residence, Leeds, MA 1 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com Design Criteria: ● Applicable Codes = Massachusetts Residential Code, 9th Edition, ASCE 7‐10 ● Roof Dead Load = 12 psf (Roof 1)  ‐‐  9 psf (Roof 2) ● Roof Live Load = 20 psf ● Wind Speed = 117 mph (Vult), Exposure B, Risk Category II ● ● Attachments: 1 ‐ 5/16" dia. lag screw with 2.5 inch min embedment depth, at spacing shown above. Sincerely, John Calvert, P.E. Project Engineer 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 Ground Snow Load = 40 psf  ‐  Roof Snow Load = 35 psf Ashton Residence, Leeds, MA 2 ____________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com Address: 1 Bernache St, Leeds, MA. 01053 Exposure: B Wind Speed: 117 mph Risk Category: II Aerial Image Ashton Residence, Leeds, MA 3 ____________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com 40 psf (ASCE7 - Eq 7-1) 1 (ASCE7 - Table 7-2) 1 (ASCE7 - Table 7-3) 1 40.0 psf (ASCE7 - Eq 7-2) 1 40.0 psf 4.03 psf 3.2 psf 4.00 ft 2.75 ft 11.00 sft 35 lb 4.00 2.00 1.52 4.00 (Enclosed Attic) 0.48 12.0 psf 15.0 psf 4.00 2.00 2.30 0.00 (Ceiling Not Vaulted) 0.70 9.0 psf 9.36 PV Dead Load = 3.22 psf (Per RGS Energy) DL Adjusted to 37 Degree Slope Point Loads of Standoffs DL Adjusted to 16 Degree Slope Miscellaneous Vaulted Ceiling Miscellaneous Total Roof DL (Roof 2) Total Roof DL (Roof 1) Roof Dead Load (Roof 2) Composition Shingle Roof Live Load = 20 psf Roof Plywood Roof Dead Load (Roof 1) 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 37 Degree Slope Gravity Loading PV System Weight Weight of PV System (Per RGS Energy) X Standoff Spacing = Y Standoff Spacing = Note: PV standoffs are staggered to ensure proper distribution of loading Roof Plywood Vaulted Ceiling 2x8 Rafters @ 24"o.c. Sistered Rafters Ashton Residence, Leeds, MA 4 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com 117 mph B Hip/Gable 16 degrees 25 ft 19.3 ft (Eq. 30.3-1) 0.7 (Table 30.3-1) 1 (Fig. 26.8-1) 0.85 (Table 26.6-1) 117 mph (Fig. 26.5-1A) II (Table 1.5-1) qh = 20.85 12.51 Zone 1 Zone 2 Zone 3 Positive GCp = -0.84 -1.39 -2.23 0.38 (Fig. 30.4-1) Uplift Pressure = -10.48 psf -17.39 psf -27.87 psf 10.0 psf (Minimum) X Standoff Spacing = 4.00 4.00 2.67 Y Standoff Spacing = 2.75 2.75 2.75 Tributary Area = 11.00 11.00 7.33 Footing Uplift = -115 lb -191 lb -204 lb Zone 1 Zone 2 Zone 3 Positive GCp = -0.84 -1.39 -2.23 0.38 (Fig. 30.4-1) Uplift Pressure = -10.48 psf -17.39 psf -27.87 psf 10.0 psf (Minimum) X Standoff Spacing = 4.00 4.00 2.67 Y Standoff Spacing = 1.67 1.67 1.67 Tributary Area = 6.68 6.68 4.45 Footing Uplift = -70 lb -116 lb -124 lb -204 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 Input Variables Wind Speed Effective Wind Area Design Wind Pressure Calculations Roof Shape Standoff Uplift Calculations-Portrait Mean Roof Height Roof Slope 667.2 lb capacity > 204 lb demand 0.6 * qh = Standoff Uplift Calculations-Landscape Wind Calculations Maximum Design Uplift = Standoff Uplift Capacity = 450 lb capacity > 204 lb demand Fastener Capacity Check Standoff Uplift Check Kz (Exposure Coefficient) = Kzt (topographic factor) = Kd (Wind Directionality Factor) = V (Design Wind Speed) = Risk Category = qh = 0.00256 * Kz * Kzt * Kd * V^2 Wind Pressure P = qh*G*Cn Exposure Category Per ASCE 7‐10 Components and Cladding Ashton Residence, Leeds, MA 5 ____________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com Framing Information & Site Specific Pictures Ashton Residence, Leeds, MA 6 ____________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com DLroof =9 psf SLroof =35 psf PV = 4 psf Name Size Grade Base Depth E (psi) I EI (lb/in.2)*(in.4) (E) Rafter 2x6 DF2 1.50'' 5.50'' 1600000 20.80 in^4 33275000 (N) Sister 2x8 DF2 1.50'' 7.25'' 1600000 47.63 in^4 76215625 33275000 109490625 DLroof = 9 psf x 0.304 = 2.74 psf SLroof = 35 psf x 0.304 = 10.64 psf PV = 4 psf x 0.304 = 1.23 psf 76215625 109490625 DLroof = 9 psf x 0.696 = 6.26 psf SLroof =35 psf x 0.696 = 24.36 psf PV = 4 psf x 0.696 = 2.81 psf Member Stiffness Check Loading Summary Methodology: As new and existing members are sistered and joined together, they will deflect the same amount. The following calculations show how loading is distributed between the two members. Member Stiffness Loading to Existing Member Loading to (E) Member = Based on relative member stiffness, 69.6 percent of total load goes to (E) member =EL(E) EL(E) + EL(N)= 30.4% Loading to (N) Member = EL(N)= = 69.6%EL(N) + EL(E) Based on relative member stiffness, 30.4 percent of total load goes to (E) member Loading to New Member Ashton Residence, Leeds, MA 7 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com (Roof 1)PASS Dead Load 15.0 psf PV Load 4.0 psf Snow Load 35.0 psf Governing Load Combo = DL + SL Total Load 54.1 psf Fb (psi) = f'b x Cd x Cf x Cr (NDS Table 4.3.1) 900 x 1.15 x 1.2 x 1.15 Allowed Bending Stress = 1428.3 psi (wL^2) / 8 = 976.4137 ft# = 11716.96 in# Actual Bending Stress = (Maximum Moment) / S = 891.7 psi L/180 (E = 1600000 psi Per NDS) = 0.566 in Deflection Criteria Based on = (5*w*L^4) / (384*E*I) = = L/611 > L/180 Therefore OK Allowed Deflection (Live Load) =L/240 0.425 in (5*w*L^4) / (384*E*I) L/945 > L/240 Therefore OK Member Area = Fv (psi) = 180 psi (NDS Table 4A) Allowed Shear = Fv * A = Max Shear (V) = w * L / 2 = 459 lb Check Bending Stress (True Dimensions) Simple Span 0.167 in 0.108 in Member Properties Member Size 2x8 S (in^3) 13.14 DF#2 Member Spacing @ 24"o.c. Maximum Moment = Check Deflection I (in^4) 47.63 Lumber Sp/Gr Actual Deflection (Live Load) = Allowed Deflection (Total Load) = Actual Deflection (Total Load) = Allowed > Actual -- 62.5% Stressed -- Therefore, OK 1958 lb Allowed > Actual -- 23.5% Stressed -- Therefore, OK 10.9 in^2 Check Shear w = 108 plf 2x8 Rafters @ 24"o.c. Member Span = 8' - 6" Framing Check Ashton Residence, Leeds, MA 8 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com (Roof 2)PASS - With Framing Upgrades Dead Load 2.7 psf PV Load 1.2 psf Snow Load 10.6 psf Governing Load Combo = DL + LL Total Load 24.0 psf Fb (psi) = f'b x Cd x Cf x Cr (NDS Table 4.3.1) 900 x 1.25 x 1.3 x 1.15 Allowed Bending Stress = 1681.8 psi (wL^2) / 8 = 1012.33 ft# = 12147.96 in# Actual Bending Stress = (Maximum Moment) / S = 1606.4 psi L/120 (E = 1600000 psi Per NDS) = 1.3 in Deflection Criteria Based on = (5*w*L^4) / (384*E*I) = = L/169 > L/120 Therefore OK Allowed Deflection (Live Load) =L/180 0.866 in (5*w*L^4) / (384*E*I) L/202 > L/180 Therefore OK Member Area = Fv (psi) = 180 psi (NDS Table 4A) Allowed Shear = Fv * A = Max Shear (V) = w * L / 2 = 311 lb Framing Check Simple Span 0.773 in 0.926 in (True Dimensions) 1485 lb Allowed > Actual -- 21% Stressed -- Therefore, OK Check Bending Stress Maximum Moment = Allowed > Actual - 95.6% Stressed -- Therefore, OK Check Deflection Allowed Deflection (Total Load) = Actual Deflection (Total Load) = Actual Deflection (Live Load) = w = 48 plf 2x6 Rafters @ 24"o.c. Member Span = 13' - 0" Member Properties - Based on Upgraded Section Member Size S (in^3) I (in^4) Lumber Sp/Gr Member Spacing 2x6 7.56 20.80 DF#2 @ 24"o.c. Check Shear 8.3 in^2 Ashton Residence, Leeds, MA 9 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 6986 Broomfield, CO 80021 530-864-7055 Domusstructural@gmail.com --(Roof 1)PASS Dead Load 6.3 psf PV Load 2.8 psf Snow Load 24.4 psf Governing Load Combo = DL + SL Total Load 33.4 psf Fb (psi) = f'b x Cd x Cf x Cr (NDS Table 4.3.1) 900 x 1.15 x 1.2 x 1.15 Allowed Bending Stress = 1428.3 psi (wL^2) / 8 = 603.9132 ft# = 7246.958 in# Actual Bending Stress = (Maximum Moment) / S = 551.5 psi L/120 (E = 1700000 psi Per NDS) = 0.85 in Deflection Criteria Based on = (5*w*L^4) / (384*E*I) = = L/981 > L/120 Therefore OK Allowed Deflection (Live Load) =L/180 0.566 in (5*w*L^4) / (384*E*I) L/1343 > L/180 Therefore OK Member Area = Fv (psi) = 180 psi (NDS Table 4A) Allowed Shear = Fv * A = Max Shear (V) = w * L / 2 = 284 lb Framing Check (N) 2x8 Sister Simple Span 0.104 in Maximum Moment = Allowed > Actual -- 38.7% Stressed -- Therefore, OK Check Deflection Allowed Deflection (Total Load) = Actual Deflection (Total Load) = w = 67 plf 2x8 Rafters @ 24"o.c. Member Span = 8' - 6" Member Properties Member Size S (in^3) I (in^4) Lumber Sp/Gr Member Spacing DF#2 @ 24"o.c.2x8 13.14 47.63 (True Dimensions) Check Bending Stress Actual Deflection (Live Load) = Check Shear 10.9 in^2 1958 lb Allowed > Actual -- 14.6% Stressed -- Therefore, OK 0.076 in Ashton Residence, Leeds, MA 10