Bass - Structural LetterRE:CERTIFICATION LETTER
Project Address: Bass Residence
99 Island Rd
Northampton, MA 01060
Design Criteria:
- Applicable Codes = 2018 IBC/IEBC W/(780 CMR) 9th Edition , 2018 IRCW/(780 CMR) 9th Edition, ASCE 7-16, and 2018 NDS
- Risk Category = II
- Wind Speed = 117 mph, Exposure Category B, Partially/Fully Enclosed Method
- Ground Snow Load = 40 psf
- Roof 1: 2x6 @ 24" OC, Roof DL = 10 psf, Roof LL/SL = 32 psf (Non-PV), Roof LL/SL = 17.5 psf (PV)
- Roof 2: 2x6 @ 24" OC, Roof DL = 10 psf, Roof LL/SL = 35 psf (Non-PV), Roof LL/SL = 33.8 psf (PV)
To Whom It May Concern,
Sincerely,
March 31, 2021
Humphrey Kariuki, P.E.
A jobsite survey of the existing framing system of the address indicated above was performed . All structural evaluation is based on the
site inspection observations and the design criteria listed above.
Existing roof structural framing has been reviewed for additional loading due to installation of PV Solar System on the roof. The
structural review applies to the sections of roof that is directly supporting the solar PV system.
Based on this evaluation, I certify that the alteration to the existing structure by installation of the PV system meets the requirements of
the applicable existing building and/or new building provisions adopted/referenced above.
Additionally, the PV module assembly including attachment hardware has been reviewed to be in accordance with the manufacturer’s
specifications and to meet and/or exceed the requirements set forth by the referenced codes.
Barun Corp | Design and Engineering | 610.202.4506 | chrisk@barun-corp.com | www.barun-corp.com
Roof 1
PV module weight 2.5 psf
Hardware assembly weight 0.5 psf
PV-DL 3 psf
Existing Roofing Material Comp Roof 1 layers 2.5 psf
Underlayment 0.5 psf
Plywood Sheathing 1.5 psf
Rafter Size and Spacing 2 x 6 @ 24 in. O.C.1.15 psf
Vaulted ceiling Yes 3 psf
Miscellaneous 1.5 psf
Total Roof Dead Load R-DL 10 psf
Expression
Roof Live Load Lo 20.0 psf
Member Tributary Area At < 200 sf
Roof 1 Roof Pitch 10/12 or 40°
Trubutary Area Reduction R1 1
Slope Roof Reduction R2 0.7
Reduced Roof Live Load Lr = Lo (R1) (R2)14.0 psf
Ground Snow Load pg 40
Effective Roof Slope 40°
Snow Importance Factor Is 1.0
Snow Exposure Factor Ce 1.0
Snow Thermal Factor Ct 1.1
Minimum Flat Roof Snow Load pf-min 35
Flat Roof Snow Load pf 35
Roof Slope Factor Cs-roof 0.92
ps-roof 32.30
Roof Slope Factor Cs-pv 0.50
ps-pv 17.50
Snow Load
Sloped Roof Snow Load on PV
Slope Roof Snow Load on Roof
Value
Material Panel AreaRoof Dead Load (R-DL)
Reduced Roof Live Load (Lr)
PV System Dead Load (PV-DL)
(All other surfaces)
(Unobstructed slippery surfaces)
Value
Barun Corp | Design and Engineering | 610.202.4506 | chrisk@barun-corp.com | www.barun-corp.com
COMPANY
Mar. 31, 2021 12:53
PROJECT
Bass Residence
Roof 1
Design Check Calculation Sheet
WoodWorks Sizer 2019 (Update 1)
Loads:
Load Type Distribution Pat- Location [ft] Magnitude Unit
tern Start End Start End
DL Dead Full Area No 10.00(24.0") psf
DL-PV Dead Partial Area No 0.00 12.80 3.00(24.0") psf
SL-PV Snow Partial Area No 0.00 12.80 17.50(24.0") psf
Maximum Reactions (lbs), Bearing Capacities (lbs) and Bearing Lengths (in) :
1'
17.078'
12.773'
Unfactored:
Dead 234 199
Snow 242 206
Factored:
Total 476 405
Bearing:
F'theta 599 599
Capacity
Joist 1042 596
Support 739 622
Des ratio
Joist 0.46 0.68
Support 0.64 0.65
Load comb #2 #2
Length 0.50* 0.50*
Min req'd 0.32** 0.34
Cb 1.75 1.00
Cb min 1.75 1.00
Cb support 1.19 1.00
Fcp sup 625 625
*Minimum bearing length setting used: 1/2" for end supports and 1/2" for interior supports
**Minimum bearing length governed by the required width of the supporting member.
Roof 1
Lumber-soft, S-P-F, No.1/No.2, 2"x6"
Supports: All - Timber-soft Beam, D.Fir-L No.2
Roof joist spaced at 24" c/c; Total length: 17.08'; Clear span: 1.275', 15.279'; Volume = 1.4 cu.ft.; Pitch: 10/12
Lateral support: top = continuous, bottom = at supports; Repetitive factor: applied where permitted (refer to online help);
This section PASSES the design code check.
WARNING: This CUSTOM SIZE is not in the database. Refer to online help.
WARNING: Your custom section is too thick for the lumber grade properties from Table 4A/B. Select a timber material
with properties from Table 4D instead.
WoodWorks® Sizer SOFTWARE FOR WOOD DESIGN
WoodWorks® Sizer 2019 (Update 1)Roof 1 Page 2
Analysis vs. Allowable Stress and Deflection using NDS 2018 :
Criterion Analysis Value Design Value Unit Analysis/Design
Shear fv = 37 Fv' = 155 psi fv/Fv' = 0.24
Bending(+) fb = 1185 Fb' = 1504 psi fb/Fb' = 0.79
Bending(-) fb = 35 Fb' = 1197 psi fb/Fb' = 0.03
Live Defl'n 0.50 = L/364 0.77 = L/240 in 0.66
Total Defl'n 1.24 = L/148 1.24 = L/148 in 1.00
Additional Data:
FACTORS: F/E(psi) CD CM Ct CL CF Cfu Cr Cfrt Ci Cn LC#
Fv' 135 1.15 1.00 1.00 - - - - 1.00 1.00 1.00 2
Fb'+ 875 1.15 1.00 1.00 1.000 1.300 - 1.15 1.00 1.00 - 2
Fb'- 875 1.15 1.00 1.00 0.796 1.300 - 1.15 1.00 1.00 - 2
Fcp' 425 - 1.00 1.00 - - - - 1.00 1.00 - -
E' 1.4 million 1.00 1.00 - - - - 1.00 1.00 - 2
Emin' 0.51 million 1.00 1.00 - - - - 1.00 1.00 - 2
CRITICAL LOAD COMBINATIONS:
Shear : LC #2 = D+S
Bending(+): LC #2 = D+S
Bending(-): LC #2 = D+S
Deflection: LC #2 = D+S (live)
LC #2 = D+S (total)
Bearing : Support 1 – LC #2 = D+S
Support 2 – LC #2 = D+S
D=dead L=live S=snow W=wind I=impact Lr=roof live Lc=concentrated E=earthquake
All LC's are listed in the Analysis output
Load combinations: ASD Basic from ASCE 7-16 2.4 / IBC 2018 1605.3.2
CALCULATIONS:
V max = 314, V design = 292 lbs; M(+) = 1176 lbs-ft; M(-) = 34 lbs-ft
EI = 49.90e06 lb-in^2
"Live" deflection is due to all non-dead loads (live, wind, snow…)
Total deflection = 1.5 dead + "live"
Bearing: Allowable bearing at an angle F'theta calculated for each support
as per NDS 3.10.3
Lateral stability(-): Lu = 15.31' Le = 23.56' RB = 20.7; Lu based on full span
Design Notes:
1. WoodWorks analysis and design are in accordance with the ICC International Building Code (IBC 2018), the
National Design Specification (NDS 2018), and NDS Design Supplement.
2. Please verify that the default deflection limits are appropriate for your application.
3. Continuous or Cantilevered Beams: NDS Clause 4.2.5.5 requires that normal grading provisions be extended to the
middle 2/3 of 2 span beams and to the full length of cantilevers and other spans.
4. Sawn lumber bending members shall be laterally supported according to the provisions of NDS Clause 4.4.1.
5. SLOPED BEAMS: level bearing is required for all sloped beams.
6. The critical deflection value has been determined using maximum back-span deflection. Cantilever deflections do not
govern design.
Roof 2
PV module weight 2.5 psf
Hardware assembly weight 0.5 psf
PV-DL 3 psf
Existing Roofing Material Comp Roof 1 layers 2.5 psf
Underlayment 0.5 psf
Plywood Sheathing 1.5 psf
Rafter Size and Spacing 2 x 6 @ 24 in. O.C.1.15 psf
Vaulted ceiling Yes 3 psf
Miscellaneous 1.5 psf
Total Roof Dead Load R-DL 10 psf
Expression
Roof Live Load Lo 20.0 psf
Member Tributary Area At < 200 sf
Roof 2 Roof Pitch 3/12 or 12°
Trubutary Area Reduction R1 1
Slope Roof Reduction R2 1
Reduced Roof Live Load Lr = Lo (R1) (R2)20.0 psf
Ground Snow Load pg 40
Effective Roof Slope 12°
Snow Importance Factor Is 1.0
Snow Exposure Factor Ce 1.0
Snow Thermal Factor Ct 1.1
Minimum Flat Roof Snow Load pf-min 35
Flat Roof Snow Load pf 35
.
Roof Slope Factor Cs-roof 1.00
ps-roof 35.00
Roof Slope Factor Cs-pv 0.97
ps-pv 33.80
Snow Load Value
Slope Roof Snow Load on Roof (All other surfaces)
Sloped Roof Snow Load on PV (Unobstructed slippery surfaces)
Reduced Roof Live Load (Lr)Value
PV System Dead Load (PV-DL)
Roof Dead Load (R-DL)Material Panel Area
Barun Corp | Design and Engineering | 610.202.4506 | chrisk@barun-corp.com | www.barun-corp.com
COMPANY
Mar. 31, 2021 12:56
PROJECT
Bass Residence
Roof 2
Design Check Calculation Sheet
WoodWorks Sizer 2019 (Update 1)
Loads:
Load Type Distribution Pat- Location [ft] Magnitude Unit
tern Start End Start End
DL Dead Full Area 10.00(24.0") psf
DL-PV Dead Partial Area 2.00 5.50 3.00(24.0") psf
SL-PV Snow Partial Area 2.00 5.50 33.80(24.0") psf
SL-RF1 Snow Partial Area 0.00 2.00 35.00(24.0") psf
SL-RF2 Snow Partial Area 5.50 7.20 35.00(24.0") psf
Maximum Reactions (lbs), Bearing Capacities (lbs) and Bearing Lengths (in) :
7.546'
7.148'0'
Unfactored:
Dead 85 85
Snow 248 248
Factored:
Total 333 333
Bearing:
F'theta 443 443
Capacity
Joist 441 441
Support 739 622
Des ratio
Joist 0.75 0.75
Support 0.45 0.54
Load comb #2 #2
Length 0.50* 0.50*
Min req'd 0.38 0.38
Cb 1.00 1.00
Cb min 1.00 1.00
Cb support 1.19 1.00
Fcp sup 625 625
*Minimum bearing length setting used: 1/2" for end supports
Roof 2
Lumber-soft, S-P-F, No.1/No.2, 2"x6"
Supports: All - Timber-soft Beam, D.Fir-L No.2
Roof joist spaced at 24" c/c; Total length: 7.55'; Clear span: 7.336'; Volume = 0.6 cu.ft.; Pitch: 3/12
Lateral support: top = continuous, bottom = at supports; Repetitive factor: applied where permitted (refer to online help);
This section PASSES the design code check.
WARNING: This CUSTOM SIZE is not in the database. Refer to online help.
WARNING: Your custom section is too thick for the lumber grade properties from Table 4A/B. Select a timber material
with properties from Table 4D instead.
WoodWorks® Sizer SOFTWARE FOR WOOD DESIGN
WoodWorks® Sizer 2019 (Update 1)Roof 2 Page 2
Analysis vs. Allowable Stress and Deflection using NDS 2018 :
Criterion Analysis Value Design Value Unit Analysis/Design
Shear fv = 35 Fv' = 155 psi fv/Fv' = 0.22
Bending(+) fb = 602 Fb' = 1504 psi fb/Fb' = 0.40
Live Defl'n 0.09 = < L/999 0.37 = L/240 in 0.23
Total Defl'n 0.13 = L/668 0.60 = L/148 in 0.22
Additional Data:
FACTORS: F/E(psi) CD CM Ct CL CF Cfu Cr Cfrt Ci Cn LC#
Fv' 135 1.15 1.00 1.00 - - - - 1.00 1.00 1.00 2
Fb'+ 875 1.15 1.00 1.00 1.000 1.300 - 1.15 1.00 1.00 - 2
Fcp' 425 - 1.00 1.00 - - - - 1.00 1.00 - -
E' 1.4 million 1.00 1.00 - - - - 1.00 1.00 - 2
Emin' 0.51 million 1.00 1.00 - - - - 1.00 1.00 - 2
CRITICAL LOAD COMBINATIONS:
Shear : LC #2 = D+S
Bending(+): LC #2 = D+S
Deflection: LC #2 = D+S (live)
LC #2 = D+S (total)
Bearing : Support 1 – LC #2 = D+S
Support 2 – LC #2 = D+S
D=dead L=live S=snow W=wind I=impact Lr=roof live Lc=concentrated E=earthquake
All LC's are listed in the Analysis output
Load combinations: ASD Basic from ASCE 7-16 2.4 / IBC 2018 1605.3.2
CALCULATIONS:
V max = 321, V design = 277 lbs; M(+) = 597 lbs-ft
EI = 49.90e06 lb-in^2
"Live" deflection is due to all non-dead loads (live, wind, snow…)
Total deflection = 1.5 dead + "live"
Bearing: Allowable bearing at an angle F'theta calculated for each support
as per NDS 3.10.3
Design Notes:
1. WoodWorks analysis and design are in accordance with the ICC International Building Code (IBC 2018), the
National Design Specification (NDS 2018), and NDS Design Supplement.
2. Please verify that the default deflection limits are appropriate for your application.
3. Sawn lumber bending members shall be laterally supported according to the provisions of NDS Clause 4.4.1.
4. SLOPED BEAMS: level bearing is required for all sloped beams.