HomeMy WebLinkAboutLA217895 - Lendel Lakeville MN Stamped___________________________________________________________________________________________
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
Lendel Residence
7970 182nd St W
Lakeville, MN. 55044
To Whom It May Concern,
Design Criteria:
●Applicable Codes = 2018 IBC/IRC, ASCE 7-16
●Roof Dead Load = 7 psf (MP1)
●Roof Live Load = 20 psf
●Wind Speed = 115 mph (Vult), Exposure C
●
●
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 28, 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 27 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'-10''.
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.
Lendel Lakeville MN 1
___________________________________________________________________________________________
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
3.37 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
7.9 psf
PV Dead Load = 3 psf (Per Blue Raven Solar)
DL Adjusted to 27 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 27 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.
Lendel 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
27 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 =-1.50 -2.50 -3.59 0.52 (Fig. 30.3)
Uplift Pressure =-30.0 psf -51.9 psf -74.5 psf 10.3 psf (Eq. 29.4-7)
ASD Uplift Pressure =-18.0 psf -31.1 psf -44.7 psf 9.6 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) = -197 lb -179 lb -174 lb
Zone 1 Zone 2 Zone 3 Positive
ya =0.75 0.80 0.80 0.75
GCp =-1.50 -2.50 -3.49 0.50 (Fig. 30.3)
Uplift Pressure =-29.2 psf -51.9 psf -72.5 psf 9.8 psf (Eq. 29.4-7)
ASD Uplift Pressure (0.6W)=-17.5 psf -31.1 psf -43.5 psf 9.6 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) = -220 lb -205 lb -195 lb
-220 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 > 220 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 > 220 lb demand
Lendel Lakeville MN 3
___________________________________________________________________________________________
Domus Structural Engineering, LLC
P.O. Box 560
Broomfield, CO 80038
530-864-7055
projects@domusstruc.com
(MP1)PASS
Dead Load 7.9 psf
PV Load 3.4 psf
Snow Load 35.0 psf
Governing Load Combo = DL + SL
Total Load 46.2 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
= 539.5924 ft#
= 6475.109 in#
Actual Bending Stress = (Maximum Moment) / S
= 2114.4 psi
L/180 (E = 1500000 psi Per NDS)
= 0.455 in
Deflection Criteria Based on =
(w*L^4) / (185*E*I)
=
= L/349 > L/180 Therefore OK
Allowed Deflection (Live Load) =L/240
0.341 in
(w*L^4) / (185*E*I)
L/461 > L/240 Therefore OK
Member Area = Fv (psi) = 135 psi (NDS Table 4A)
Allowed Shear = Fv * A = Max Shear (V) = w * L / 2 = 316 lb
Check Bending Stress
(True Dimensions)
Continuous Span
0.235 in
0.178 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 -- 96.9% Stressed -- Therefore, OK
709 lb
Allowed > Actual -- 44.6% Stressed -- Therefore, OK
5.3 in^2
Check Shear
w = 92 plf
2x4 Top Chords @ 24"o.c.
Member Span = 6' - 10"
Framing Check
Lendel 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
●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.
●All report conclusions represent Domus Structural Engineering, LLC's best professional judgment based upon industry
standards.
●Resolve any conflicts on the drawings with Domus Structural Engineering, LLC before proceeding with construction.
●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.
●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.
●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.
●Any and all waterproofing shall be provided by the contractor. Domus Structural Engineering, LLC is not responsible for
waterproofing.
●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
●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
●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.
●No structural members can be cut for conduit, etc., unless specifically shown. Obtain prior written approval for installation of
any additional conduit, etc.
●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.
●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.
●Flexible utility connections must be used at any building seismic joint.
●Care should be taken to ensure that PV arrays do not preclude drainage of rain water.
●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.
●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.
●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.
●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.
Lendel Lakeville MN 5