Kyle Field - Tech Report Complete 2

Proposed Roof System Substitution Under Superimposed Solar Panel Load

By : Kyle Field

7 1 3 0 8 0 A v e C a l g a r y A B

Proposed Roof System
Substitution Under
Superimposed Solar Panel Load


ETR592 ENGINEERING TECHNICAL REPORT
Proposed Roof System Substitution Under
Superimposed Solar Panel Load
Technical Report First Draft
Prepared for :
Professor Kay-Ann Williams
By : Kyle Field
3/6/2014


i

Abstract
The provision of energy is a major concern for our society. Photovoltaic solar panels can be used
to help supplement the energy requirements demanded by our society. Flat industrial and
commercial rooftops could be a potential opportunity to install PV solar panels, however, many
roofs were not designed to support the additional weight. A proposed roof system substitution is
presented to help decrease the total dead load acting on an open web steel joist system. A
theoretically existing roof structure was designed, followed by the theoretical addition of
superimposed solar panels on that roof. This resulted in the capacity of the open web steel joist to
be insufficient to support the additional load. A proposed substitution from a heavier built up roof
system to a lighter single ply membrane is presented as a possible solution. The single ply
membrane design is included within this report, and is designed to meet the shear, moment and
deflection requirements under ultimate limit states and serviceability limit states design.


ii

Acknowledgements
I would like to thank Eric Stephenson, the director of engineering and technology for HB Solar
Canada, and Icopal Group for helping to provide data that made this report possible. I would also
like to thank Professors Maura Lecce and Kay-Ann Williams for all their help and support during
the writing process of this report.


Table of Contents
Abstract………………………………………………….…………………………………………..i
Acknowledgements.…………………………………………..…………………………………….ii
List of Figures and Tables……………………………….……………………………………….....v
1.0 Introduction………………………………………….………………………………………….1
1.1 Background………………………………………………………………………………...1
1.2 Purpose…………………………………………………………………………………...1-2
1.3 Scope of Work………………………………………………………………………...….2-3
2.0 Review of Common Industrial & Commercial Built-Up Flat Roof Designs…………………...3
2.1 Typical Built-Up Flat Roof Construction ……………………………………………….3-4
2.2 Determining Common Lengths & Spacings of OWSJ’s used in Big Box Stores.…….…4-5
2.3 Determining the Total Factored and Service Loads Imposed on the OWSJ……………..5-7
2.4 OWSJ Selection and Checks …………………………………………………………….7-9
2.5 OWSJ Deflection and Checks.………………….………………………………………9-10
3.0 PV Solar Panel and Ballast Mounting System Weight Review …………………...………….10
3.1 HB Solar Ballast Mounting System and Solar Array ...……………………………….10-11
4.0 Review of Superimposed PV Solar Panels and Increased Snow Load..………………………11
4.1 Adjusting the Total Factored and Service Loads to reflect the Increased Loading……11-12
5.0 Design Checks…………...……………………………………..……………………………...13
5.1 OWSJ Checks….………………….…………………………………………………........13
5.2 OWSJ Deflection and Checks. ………………………………………………………..13-14


Table of Contents Continued
6.0 Conclusion ……………………………………………………………………………….........15
7.0 Recommendation.………………..…………………………………………………………….15
7.1 Substitution from a BUR system to an Icopal Universal Single Ply Membrane ……..15-16
7.2 Icopal Universal POCB Single Ply Membrane Load.…………..……………………..16-17
7.3 Adjusting the Total Factored and Service Loads to reflect the Substituted Loading.....17-18
7.4 Design Checks…………………………………………………………………….............18
7.5 OWSJ Deflection and Checks………………………………………………………....18-20
7.6 Conclusion…….…………………………………………………………………………..20
References…………………………………………………………………………………………21
Glossary……………………………………………………………………………………………22


v

Tables & List of Illustrations
Figure 1 – Typical Built-Up Flat Roof Cross Section……………....………………………………3
Figure 2 – Typical Structural Steel Layout………………………………..……………………......4
Figure 3 – Joist and Joist Girder Catalogue – Joist depth selection tables.………..……………......7
Figure 4 – Icopal Universal POCB Single Ply Membrane Cross Section..………..……………....16
Table 1 – Average Open Web Steel Joist Span and Spacing……………………………...…..……4
Table 2 – Typical Dead Loads………………………………..……………………………………..5
Table 3 – Icopal Universal POCB Single Ply Membrane Roll Size and Weight….……………....16
Appendices
Appendix ‘A’ – Specified Snow Load S1..…………………………………….…..…………...23-24
Appendix ‘B’ – Specified Snow Load S2..………..……………………………………………25-26


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1.0 Introduction
Many existing industrial & commercial roofs were not designed to structurally support the
extra force applied after the installation of solar panels. Therefore, the current existing
design, in many cases, is insufficient to support the superimposed load. Based on the
structural analysis of an existing roof design, it may be necessary to substitute the roof
system. To help promote the widespread use of solar panels on industrial & commercial
rooftops we must find a fast, efficient and inexpensive solution. I envision substituting the
existing roof system with a lightweight roof membrane. The substitution from a heavier
traditional build-up roof system to a lightweight roof membrane could potentially
counterbalance and offset the additional load produced by the solar panels without having to
completely modify the original design.
1.1 Background
The provision of energy is a major concern for our society. Photovoltaic (PV) solar panels
can be used to help supplement the energy requirements demanded by our society. Flat
industrial and commercial rooftops, like those constructed for major big box stores, such as
Wal-Mart, could be a potential opportunity to install PV solar panels. But, often the
complexity and costs associated with reinforcing the roof can be a deterrent. Therefore, in
order to encourage the installation of PV solar panels on flat industrial and commercial
rooftops, we must find a simple, cost effective solution.
1.2 Purpose
For the purpose of this report we are going to look at a theoretical design of an industrial or
commercial roof system using standard loads that can be found in the Handbook of Steel
Construction – Tenth Edition, determine the most common length and spacing of open web
steel joists (OWSJs) used in similar applications by visiting common big box stores and
measuring the necessary dimensions, and using the CANAM Catalogue for the selection of
our OWSJ. This will set the benchmark of our theoretical existing building.


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We will then review common PV solar panel loads acquired from suppliers, look at the
theoretical superimpose load applied and review the structural stability of the selected OWSJ
Member.
If the OWSJs are unable to support the additional load then we will analyze our theoretical
existing roof structure and determine an adequate solution that will meet the shear, moment
and deflection requirements necessary to adequately support the additional load of solar
panels by reviewing modern lightweight roof membranes to substitute with the existing roof
system.
1.3 Scope of work
This reports specific topic is only applicable to existing industrial and commercial Built-Up
Flat Roof (BUR) systems where the structural support provided by the OWSJs are
insufficient to bear the additional axial load applied after the installation of solar panels.
This report will only apply to buildings that were designed and constructed abiding by the
1997 Ontario Building Code (OBC) or 1995 National Building Code of Canada (NBCC)
standards. This report will be addressing 2 issues – the extra weight of solar panels and the
increased snow load from a 1 in 30 year storm (under the 1995 NBCC standards) to a 1 in 50
year storm (under the current 2010 NBCC standards). This report will not cover the design
of proposed residential, commercial, or industrial roof systems, nor will this report consider
any snow load accumulation. The following is the proposed approach in determining:
Ø whether an existing flat commercial or industrial rooftop is capable of providing enough
structural support to resist the superimposed PV solar panel load. If not,
Ø determining an adequate solution.


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Figure 1 - Typical Built-Up Flat Roof Cross Section
2.0 - Review of Common Industrial & Commercial Built-Up Flat Roof Designs
3.0 - PV Solar Panel and Ballast Mounting System Weight Review
4.0 – Review of Superimposed PV Solar Panels and Increased Snow Load
5.0 – Design Checks
6.0 - Conclusion
7.0 - Recommendations

2.0 Review of Common Industrial & Commercial Built-Up Flat Roof Designs
2.1 Typical Built-Up Flat Roof Construction
Built-Up Flat Roofs have been used on industrial and commercial buildings since the 1870s,
and although emerging technologies have been used to help improve the longevity and
efficiency of these roof types, the general design and construction has remained the same. For
the purpose of this report we are going to be looking at a more modern BUR application that
would be common with big box stores such as Wal-Mart. See Figure-1 below.
Figure 1 shows the various layers that
make up the BUR. The deck surface, in
this type of application, would be a ribbed
steel deck that sits on and is attached to the
OWSJs by either welds or bolts. Then
Rigid Fiberglass Insulation would be
placed over the steel decking, followed by
a thin layer of hot asphalt or bitumen oil to
help adhere the gypsum cover board. There would finally be 4 layers of hot asphalt oil and ply
sheets, and in most cases this is all covered in gravel, which the figure does not depict.
This sums up the BUR dead loads that the OWSJ would have to support, however there are
still additional dead loads applied to the joist. These additional loads consist of various


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Figure 2 - Typical Structural Steel Layout
Table 1 - Average Open Web Steel Joist Span and Spacing
mechanical applications such as ductwork, piping, and electrical fixtures as well as the self-
weight of the OWSJ. Also, as most of these big box stores are built in North America, snow
loads are an additional live load calculation associated with the design of BURs. For the
purpose of this report, the snow load calculation will be based on a large commercial building
in Newmarket Ontario.
2.2 Determining Common Lengths & Spacings of OWSJs used in Big Box Stores
Several Big-Box stores were studied throughout Newmarket Ontario on January 10, 2013 to
help determine common OWSJ spans and spacings. See Figure 2 for a schematic drawing of
an OWSJ system to help clarify the
arrangement of a typical roof system.
Figure 2 illustrates the OWSJs spanning
between the supporting beams and the
spacing between each joist.
See Table 1 below for the results.
After examining multiple stores that
utilize BUR systems supported by OWSJ
systems, the resulting average span is
NAME ADDRESS OWSJ SPAN OWSJ SPACING
Super Store
18120 Yonge Street
Newmarket, ON
14.0m 2.0m
Home Depot 17850 Yonge Street
Newmarket, ON
13.0m 1.8m
The Brick
17940 Yonge Street
Newmarket, ON
12.0m 1.8m
Stitches
18170 Yonge
Newmarket, ON
12.0m 1.6m
Costco
18182 Yonge Street
East Gwillimbury, ON
14.0m 1.8m


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Table 2 - Typical Dead Loads
13.0m with an average spacing of 1.8m. This data will be used to determine the total factor
load imposed on the theoretical existing OWSJ.
2.3 Determining the Total Factored and Service Loads Imposed on the OWSJ
In order to determine the total factored load acting on an OWSJ we must first add up all of the
dead loads that the joist supports. Typical dead loads can be found in the Handbook of Steel
Construction – Tenth Edition, Part 7 – Mass and Forces for Materials. Then the snow load
must be calculated following the formula provided in the Ontario Building Code, Part 4;
section 4.1.6.2 using ground snow and rain loads for a specific location as tabulated in
Appendix C of the 1995 NBCC. We are using the 1995 NBCC climatic data because we are
assuming that the theoretical existing building was built between 1995 and 2005. Therefore
we will be using less stringent climatic data for a 1 in 30 year storm. Since we are going to be
doing a structure analysis of this theoretically existing building later on, we will then have to
follow the current 2010 NBCC using the more stringent climatic data for a 1 in 50 year storm.
Finally the live load and dead loads are factored according to the Ontario Building Code, Part
4; Table 4.1.3.2 in order to provide a safety margin.
For the various dead loads that a typical OWSJ system supports see Table 2 below.
DEAD LOADS
MATERIAL FORCE (kN/m2
)
4 Ply Asphalt & Gravel 0.32
Rigid Fibre Glass Insulation 0.28
Corrugated Steel Deck 0.10
Mechanical (Ducts/ pipes/ wiring) 0.30
Open Web Steel Joist and Steel Components 0.25
TOTAL 1.25
The specified snow load (or live load) is calculated using the following formula as tabulated in
the Ontario Building Code, Part 4; section 4.1.6.2,
S = Is [Ss(CbCwCsCa) + Sr]


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where,
Is = importance factor for snow load as provided in Table 4.1.6.2. ,
Ss = 1-in-30-year ground snow load, in kPa, determined in accordance with Subsection 1.1.2. ,
Cb= basic roof snow load factor in Sentences (2),
Cw= wind exposure factor in Sentences (3) and (4),
Cs= slope factor in Sentences (5), (6) and (7),
Ca= shape factor in Sentence (8), and
Sr= 1-in-30-year associated rain load, in kPa, determined in accordance with Subsection 1.1.2.
, but not greater than Ss(CbCwCsCa).
The resulting specified snow load using the 1995 NBCC ground snow and rain loads (lets call
this S1) is 2.1kN/m2
. Further details of all calculations can be observed in Appendix ‘A’.
The live load, L, and dead load, D, can now be factored. According to the Ontario Building
Code, Part 4; Table 4.1.3.2. , Load Combinations for Ultimate Limit States, Case 2, Principle
Loads,
Wf = (1.25D) + (1.5L)
Wf = (1.25 x 1.25kN/m2
) + (1.5 x 2.1kN/m2
)
Wf = 4.7kN/m2
Finally the resulting Wf of 4.7kN/m2
can be converted into a load per meter (kN/m) along the
span of the OWSJ resulting in ultimate limit states (ULS) design criteria. The ULS design is
used to consider the safety of the building. This is calculated by multiplying the tributary
width, which is simply the spacing between each joist, by the Wf. As found in Section 2.2 of
this report, the spacing is 1.8m. Therefore,
WULS = 1.8m x 4.7kN/m2
= 8.5kN/m


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Figure 3 - Joist and Joist Girder Catalogue – Joist depth selection tables
Before selecting an appropriate OWSJ, we also must calculate the loads for serviceability limit
states (SLS) to ensure that the deflection based on the criteria of L/360 under live load (or
snow load) and L/240 under total load (or snow load + dead load) will be satisfied. For the
purpose of this report, we are going to label the criteria of L/360 under live load as SLS1.1 and
criteria of L/240 under total load as SLS2.1. SLS is used for designing the building for only its
intended purpose, which in this case is simply supporting the dead loads and live load (or
snow load), and does not take any fatigue or safety in to consideration. This means that the
loads acting on the OWSJ are not factored, which will provide us with accurate and unaltered
deflection estimations.
WSLS1.1 = Tributary width x Unfactored Snow Load
WSLS1.1 = 1.8m x 2.1kN/m2
= 3.8kN/m
WSLS2.1 = Tributary width x Total Unfactored Load
WSLS2.1 = 1.8m x (2.1kN/m2
+ 1.25kN/m2
) = 6.0kN/m
Now that the WULS1, WSLS1.1 and WSLS2.1 have been calculated, we can select our theoretical
existing OWSJ.
2.4 OWSJ Selection and Checks
Canam has specialized in fabricating OWSJ’s, girders and steel decks for over 50 years, and is
a primary supplier to many large-scale construction projects. For this reason we will be
selecting the OWSJ used in our theoretical existing building from the Canam Catalogue.


8

Figure 3 has been taken out of the Canam – Joist and Joist Girder Catalogue – Joist depth
selection tables. This table is used to select an appropriate OWSJ depth based on the span,
factored load (or WULS1) and service loads (or WSLS1.1 and WSLS2.1). Since the span of the
OWSJ being designed is 13.0m, the appropriate table has been obtained from the catalogue as
seen on the far left column of the table.
As previously acquired in section 2.3, the factored load (or WULS1) and service loads (WSLS1.1
& WSLS2.1) being imposed on the theoretical OWSJ are 8.5kN/m, 3.8kN/m and 6.0kN/m
respectively. Along the top row of figure 3 is a series of factored loads that the OWSJ can
support, and below each column is a list of each OWSJs mass (top number) in kg/m and the
percent of service load to produce a deflection of L/360 (bottom number).
The joist depth is selected by first finding a factored load on the table greater than the design-
factored load (or WULS1). On figure 3 highlighted in green is a factored load of 9.0kN/m,
which is greater than 8.5kN/m, and a service load of 6.0kN/m. The next step is to follow the
column down and select the lightest OWSJ. Highlighted in orange is the lightest OWSJ at
17.4kg/m with the ability to support 70% of the service load to produce a deflection of L/360.
Therefore the OWSJ can support (70/100) x 6.0kN/m = 4.2kN/m of the maximum service
load, which is greater than 3.8kN/m. We can conclude that the deflection based on the criteria
of L/360 under live load (or WSLS1.1) is satisfied since the live load (or snow load) on the roof
is 3.8kN/m and thus the actual deflection under the load of 3.8kN/m is less than L/360. We
will prove this in section 2.5.
Next we have to determine if the OWSJ will meet the criteria of L/240 under total load (or
WSLS2.1) before selecting the appropriate depth. Since the tables are based on the criteria of
L/360 under live load, we must use a ratio to convert the criteria to reflect L/240 under total
load. Therefore, the OWSJ can support (360/240) x (70/100) x 6.0kN/m = 6.3kN/m of the
maximum service load, which is greater than 6.0kN/m. We can conclude that the deflection
based on the criteria of L/240 under total load (or WSLS2.1) is satisfied since the total load (or
live load + dead load) on the roof is 6.0kN/m and thus the actual deflection under the load of
6.0kN/m is less than L/240. We will prove this in section 2.5.


9

Finally follow the row over to the left and determine the OWSJ depth. Highlighted in red is
the OWSJ depth selection of 800mm.
2.5 OWSJ Deflection and Checks
The final step in the OWSJ selection is to determine the deflection. Deflection is determined
using only the service loads (or WSLS1.1 and WSLS2.1) of 3.8kN/m and 6.0kN/m respectively.
The deflection, D, of the OWSJ for the criteria of L/360 under live load is calculated using the
following formula,
D = (LL/SL) x (L/360)
where,
LL = live load (or snow load) in kN/m,
SL = % of service load to produce a deflection of L/360 (kN/m),
L = length of OWSJ (mm).
Therefore,
D = (3.8kN/m / 4.2kN/m) x (13000 / 360)
D = 33mm
The resulting deflection of the theoretically existing OWSJ for a typical BUR system based on
the deflection criteria of L/360 is 33mm. We can prove that the deflection based on the criteria
of L/360 under live load is satisfied since the deflection of the OWSJ is 33mm, which is less
than L/360,
13000mm/360 = 36mm
33mm < 36mm


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The deflection, D, of the OWSJ for the criteria of L/240 under total load is,
D = (6.0kN/m / 6.3kN/m) x (13000 / 240)
D = 52mm
The resulting deflection of the theoretically existing OWSJ for a typical BUR system based on
the deflection criteria of L/240 is 52mm. We can prove that the deflection based on the criteria
of L/240 under total load is satisfied since the deflection of the OWSJ is 52mm, which is less
than L/240,
13000mm/240 = 54mm
52mm < 54mm
This concludes the design and selection of the theoretically existing OWSJ roof structure that
would typically be used in a large commercial or industrial flat BUR system.
3.0 PV Solar Panel and Ballast Mounting System Weight Review
3.1 HB Solar Ballast Mounting System and Solar Array
HB Solar is an experienced solar panel installation company with over 200 projects under their
belt. They have installed on all major roof types including, traditional built up roofs, which
makes them a good resource of information for this report.
On January 12, 2013, a phone interview was conducted with Eric Stephenson, the Director of
Engineering and Technology for HB Solar Canada. The scope of this report was conveyed to
him followed by a series of questions. The main source of data requested from Eric was the
total unfactored ballast and solar panel loading. He explained that they could supply solar
panel ballast systems in inclinations from 5 to 30 degrees in 5 degree intervals, and that the
various inclinations will be slightly different in loading from 3-4psf (0.14 - 0.20kN/m2
). He
further explained that the higher the inclination, for example 25-30 degrees, the tighter or
closer together each row of solar panels can be placed together, therefore increasing the total
weight.


11

For the purpose of this report, the loading from the solar and ballast array will be selected
using the steeper inclination of 30 degree, therefore resulting in a load of 4psf or 0.20kN/m2
.
This will consider the worst-case loading scenario and result in the highest yield of energy
from the PV solar panels.
4.0 Review of Superimposed PV Solar Panels and Increased Snow Load
4.1 Adjusting the Total Factored and Service Loads to reflect the Increased Loading
With the addition of the PV solar panels and ballast system on the theoretically existing roof,
the dead load must be adjusted to reflect the loading that the existing OWSJ must support.
Also, bear in mind that we have design the theoretically existing roof system in Section 2 using
ground snow and rain loads as provided in Appendix C of the 1995 NBCC. Since we are doing
a structural analysis of this theoretically existing building in 2014, we must abide by the
current 2010 NBCC ground snow and rain loads. The same steps will be followed as in section
2.3 of this report.
The adjusted total dead load is the previously determined total dead load as provided in table 2,
plus the additional loading of the PV solar panels. Therefore,
1.25kN/m2
+ 0.20kN/m2
= 1.45kN/m2
.
The specified snow load (live load) is calculated using the following formula,
where,


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The resulting specified snow load using the 2010 NBCC ground snow and rain loads (lets call
this S2) is 2.3kN/m2
. Further details of all calculations can be observed in Appendix ‘B’.
The resulting total factored load is,
Wf = (1.25D) + (1.5L)
Wf = (1.25 x 1.45kN/m2
) + (1.5 x 2.3kN/m2
)
Wf = 5.3kN/m2
Note that the factored load has increased from 4.7kN/m2
(as determined in section 2.3) to
5.3kN/m2
.
Next the WULS2, WSLS1.2 and WSLS2.2 can be calculated using the same tributary width of 1.8m
as determined in section 2.2. Note that the initial snow load of 2.1kN/m2
(or S1) has increased
to 2.3kN/m2
(or S2)
WULS2 = 1.8m x 5.3kN/m2
= 9.5kN/m
WSLS1.2 = 1.8m x 2.30kN/m2
= 4.1kN/m
WSLS2.2 = 1.8m x (1.45kN/m2
+ 2.30kN/m2
)= 6.8kN/m
Note that the WULS2, WSLS1.2 and WSLS2.2 have increased from 8.5kN/m to 9.5kN/m, 3.8kN/m
to 4.1kN/m, and 6.0kN/m to 6.8kN/m respectively as determined in section 2.3.


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5.0 Design Checks
5.1 OWSJ Checks
The joist depth as selected in Section 2.4 of this report, required a maximum factored load of
9.0kN/m before being considered insufficient to support the roof. However, the design-
factored load (or WULS2) is 9.5kN/m. On figure 3 highlighted in green is a factored load of
9.0kN/m, which is less than 9.5kN/m, therefore the theoretically existing OWSJ is insufficient
to support the additional snow load, S2, (using the 2010 NBCC ground snow and rain loads) as
well as the additional load produced by the PV solar panels.
As determined in Section 2.4 of this report, the OWSJ can support (70/100) x 6.0kN/m =
4.2kN/m of the maximum service load, which is greater than 4.1kN/m. We can conclude that
the deflection based on the criteria of L/360 under live load (or WSLS1.2) is satisfied since the
live load (or snow load) on the roof is 4.1kN/m and thus the actual deflection under the load of
As determine in Section 2.4 of this report, the OWSJ can support (360/240) x (70/100) x
6.0kN/m = 6.3kN/m of the maximum service load, which is less than 6.8kN/m. We can
conclude that the deflection based on the criteria of L/240 under total load (or WSLS2.2) is not
satisfied since the total load (or live load + dead load) on the roof is 6.8kN/m and thus the
actual deflection under the load of 6.8kN/m is greater than L/240. We will prove this in
section 5.2.
As mentioned in Section 2.5 of this report, deflection is determined using only the service
loads. The adjusted service loads as determined in Section 4.1 of this report, WSLS1.2 and
WSLS2.2, are 4.1kN/m and 6.8kN/m respectively. The deflection, D, of the OWSJ for the
criteria of L/360 under live load is calculated using the following formula,
D = (LL/SL) x (L/360)


14

where,
Therefore,
D = (4.1kN/m / 4.2kN/m) x (13000 / 360)
D = 35mm
After the loading has been adjusted to reflect the superimposed PV solar panels and increase
snow load, the resulting deflection of the theoretically existing OWSJ for a typical BUR
system based on the deflection criteria of L/360 is 35mm. We can prove that the deflection
based on the criteria of L/360 under live load is satisfied since the deflection of the OWSJ is
35mm, which is less than L/360,
13000mm/360 = 36mm
35mm < 36mm
D = (6.8kN/m / 6.3kN/m) x (13000 / 240)
D = 59mm
After the loading has been adjusted to reflect the superimposed PV solar panels and increase
snow load, the resulting deflection of the theoretically existing OWSJ for a typical BUR
system based on the deflection criteria of L/240 is 59mm. We can prove that the deflection
based on the criteria of L/240 under total load is not satisfied since the deflection of the OWSJ
is 59mm, which is greater than L/240,
13000mm/240 = 54mm


15

59mm > 54mm
6.0 Conclusion
We can conclude that the theoretically existing OWSJ within a building built between 1995
and 2005 supporting a typical BUR system in Newmarket Ontario abiding by the 1995 NBCC
standards would be insufficient to support the additional load produced by both the instillation
of PV solar panels and increase snow load of a 1 in 50 year storm as presented in the 2010
NBCC apposed to a 1in 30 year storm as presented in the 1995 NBCC.
7.0 Recommendation
7.1 Substitution from a BUR system to an Icopal Universal Single Ply Membrane
Icopal is a roofing and waterproofing company based out of Manchester UK and is a world
leader in building protection with 160 years of experience. They have 35 productions sites
throughout Europe and the US that develop and produce a wide range of roofing and
waterproofing construction solutions.
One of the products that Icopal has developed is a single ply roofing membrane. These
membranes are lightweight, flexible, UV resistant, and much easier to install, which makes
them a safer, cheaper, and quicker then traditional BUR systems. Single ply roof membranes
are excellent alternatives that provide tremendous thermal insulation and airtight construction,
thus reducing a building carbon footprint. Also, these membranes can be recycled after
reaching their potential 30-year lifespan, which also contributes to a buildings sustainability.
Single ply roof membranes can be used on all types of buildings including commercial, retail,
residential, and refurbishment projects.
Icopal has developed 4 types of single ply membrane products, however, this report is going
to specifically consider the Icopal Universal Polyolefin Copolymerisate Binder (POCB) single
ply membrane as a potential alternative. The Icopal Universal POCB single ply roof system
can be quickly applied to various materials such as insulation, timber, concrete, and existing
bitumen roofing systems.


16
Figure 4 - Icopal Universal POCB
Single Ply Membrane Cross Section
I propose removing the existing 4 ply asphalt and gravel down to the insulation, and replacing
with the Icopal Universal POCB single ply membrane. This would significantly reduce the
total dead load, which could theoretically offset the weight from the additional solar panels
and increase snow load. Therefore the total factored load and service loads could potentially
remain within the capacity of the OWSJ.
7.2 Icopal Universal POCB Single Ply Membrane Load
The Icopal website does not provide any specific loads for their Universal POCB single ply
membrane, however, they do provide a table illustrating the roll size and weight for this
specific product. This means that we can interpolate the necessary load.
Table 3 illustrate the Icopal Universal POCB single ply membrane product roll size and
weight. Each role weighs 32kg and covers 1m x 10m = 10m2
. Therefore the membrane weighs
32kg / 10m2
= 3.2kg/m2
. Now we need to convert this load into kN/m2
by using the
conversion factor of 0.009807kN/m2
per 1kg/m2
, therefore 0.009807kN/m2
x 3.2kg/m2
=
0.03kN/m2
. Now we have the loading for the Icopal Universal POCB single ply membrane
based on table 3, however, when the membrane is applied onto the roof insulation there is an
overlap as depicted in figure 3 below.
1. Icopal Universal®.
2. Icopal Membrane Tubular Washer.
3. Icopal Insulation Tubular Washer.
4. Thermazone insulation board.
5. Vapour Control Layer.
6. Structural deck.
Product
Code
Description Roll Size Roll
Weight
3007125 Universal (POCB) 10m x 1m 32kg
3007124 Universal SA
(Heat Activated Detail Sheet)
10m x 1m 32kg
3007146 Universal WS
(Anti Root - FLL Approved)
10m x 1m 35kg
Table 3 - Icopal Universal POCB Single Ply Membrane Roll Size and Weight


17

In order to consider the worst-case scenario, we will assume that the membrane will have an
overlap of half its produced 1.0m width and thus resulting in the membrane being 2 layers
thick. Therefore the loading from the Icopal Universal POCB single ply membrane would be
0.03kN/m2
x 2 = 0.06kN/m2
.
7.3 Adjusting the Total Factored and Service Loads to reflect the Substituted Loading
The adjusted total dead load is the previously determined total dead load as provided in table 2,
plus the additional loading of the PV solar panels, subtract the 4 ply asphalt and gravel, plus
the Icopal Universal SOCB single ply membrane.
Therefore,
1.25kN/m2
+ 0.20kN/m2 - 0.32kN/m2
+ 0.06kN/m2
= 1.19kN/m2
.
The specified snow load (live load) will remain the same as determined in section 4.1
following the current 2010 NBCC standard at 2.3kN/m2
.
The resulting total factored load is,
Wf = (1.25D) + (1.5L)
Wf = (1.25 x 1.19kN/m2
) + (1.5 x 2.3kN/m2
)
Wf = 4.9kN/m2
Note that the factored load has decreased from 5.3kN/m2
(as determined in section 4.1) to
4.9kN/m2
.
Next the WULS3, WSLS1.3 and WSLS2.3 can be calculated using the same tributary width of 1.8m
as determined in section 2.2.
WULS3 = 1.8m x 4.9kN/m2
= 8.8kN/m
WSLS1.3 = 1.8m x 2.30kN/m2
= 4.1kN/m
WSLS2.3 = 1.8m x (1.19kN/m2
+ 2.30kN/m2
)= 6.3kN/m


18

Note that the WULS3 and WSLS2.3 have decreased from 9.5kN/m to 8.8kN/m, and 6.8kN/m to
6.3kN/m respectively as determined in section 4.1. The WSLS1.3 has remained the same at
4.1kN/m.
7.4 Design Checks
The joist depth as selected in Section 2.4 of this report, required a maximum factored load of
9.0kN/m before being considered insufficient to support the roof. After substituting the 4-ply
asphalt and gravel load with the Icopal Universal POCB single ply membrane, the new design-
factored load (or WULS3) is 8.8kN/m. On figure 3 highlighted in green is a factored load of
9.0kN/m, which is greater than 8.8kN/m, therefore the theoretically existing OWSJ is
sufficient to support the additional snow load, S2, (using the 2010 NBCC ground snow and rain
loads) as well as the additional load produced by the PV solar panels.
As determined in Section 2.4 of this report, the OWSJ can support (70/100) x 6.0kN/m =
4.2kN/m of the maximum service load, which is greater than 4.1kN/m. We can conclude that
the deflection based on the criteria of L/360 under live load (or WSLS1.3) is satisfied since the
live load (or snow load) on the roof is 4.1kN/m and thus the actual deflection under the load of
As determine in Section 2.4 of this report, the OWSJ can support (360/240) x (70/100) x
6.0kN/m = 6.3kN/m of the maximum service load, which is equal to the WSLS2.3 of 6.3kN/m.
We can conclude that the deflection based on the criteria of L/240 under total load (or WSLS2.3)
is satisfied since the total load (or live load + dead load) on the roof is 6.3kN/m and thus the
actual deflection under the load of 6.3kN/m is equal to L/240. We will prove this in section
7.5.
As mentioned in Section 2.5 of this report, deflection is determined using only the service
loads. The adjusted service loads as determined in Section 7.3 of this report, WSLS1.3 and
WSLS2.3, are 4.1kN/m and 6.3kN/m respectively. The deflection, D, of the OWSJ for the
criteria of L/360 under live load is calculated using the following formula,


19

D = (LL/SL) x (L/360)
where,
Therefore,
D = (4.1kN/m / 4.2kN/m) x (13000 / 360)
D = 35mm
After the loading has been adjusted to reflect the superimposed PV solar panels, increase snow
load, and substituted 4ply asphalt and gravel with the Icopal Universal SOCB single ply
membrane, the resulting deflection of the theoretically existing OWSJ based on the deflection
criteria of L/360 is 35mm. We can prove that the deflection based on the criteria of L/360
under live load is satisfied since the deflection of the OWSJ is 35mm, which is less than
L/360,
13000mm/360 = 36mm
35mm < 36mm
D = (6.3kN/m / 6.3kN/m) x (13000 / 240)
D = 54mm
After the loading has been adjusted to reflect the superimposed PV solar panels, increase snow
load, and substituted 4ply asphalt and gravel with the Icopal Universal SOCB single ply
membrane, the resulting deflection of the theoretically existing OWSJ based on the deflection
criteria of L/240 is 54mm. We can prove that the deflection based on the criteria of L/240


20

under total load is satisfied since the deflection of the OWSJ is 54mm, which is equal to
L/240,
13000mm/240 = 54mm
54mm = 54mm
7.6 Conclusion
We can conclude that by substituting a BUR system to an Icopal Universal POCB single ply
membrane system that the theoretically existing OWSJ within a building built between 1995
and 2005 in Newmarket Ontario abiding by the 1995 NBCC standards would be sufficient to
support the additional load produced by both the instillation of PV solar panels and increase
snow load of a 1 in 50 year storm as presented in the 2010 NBCC apposed to a 1in 30 year
storm as presented in the 1995 NBCC.


21

REFERENCES
Canadian Institute of Steel Construction. Handbook of Steel Construction.10th
ed. 14th
Ave,
Markham, Ontario, Canada: 2010. Print
CANAM Group. Joist and Joist Girder Catalogue. Drew Road, Mississauga, Ontario, Canada.
Icopal Limited. Icopal Universal Product Information Sheet. Barton Dock Road, Stretford,
Manchester, UK: Retrieved March 1, 2014, from
http://www.icopal.co.uk/Products/Single_Ply_Roofing/universal.aspx.
Kyle E Field, Seneca College Student, Toronto, Ontario, in conversation with Maura Lecce, Steel
Design Professor Seneca College of Applied Arts & Technology, Toronto, Ontario, March 2,
2014.
Kyle E Field, Seneca College Student, Toronto, Ontario, in conversation with Eric Stephenson,
Director of Engineering and Technology from HB Solar Canada, Woodbridge, Ontario. January
12, 2013.
National Building Code of Canada. Canadian Commission on Building and Fire Codes National
Research Concil of Canada, Ottawa , Ontario, Canada: 1995. Print
National Building Code of Canada. Canadian Commission on Building and Fire Codes National
Research Concil of Canada, Ottawa , Ontario, Canada: 2010. Print
Ontario Building Code. Building and Development Branch of the Ministry of Municipal Affairs
and Housing, Toronto, Ontario, Canada: 1997. Print
Ontario Building Code. Building and Development Branch of the Ministry of Municipal Affairs
and Housing, Toronto, Ontario, Canada: 2006. Print


22

GLOSSARY
Axial Load – Refers to the vertical force applied to a structural framing system.
Dead Load – Refers to the axial force that a specific material imposes on a structural framing
system.
Deflection – Refers to the distance in millimeters that a structural steel member bends from its
original unloaded position to its fully applied axial load position.
Depth – Refers to the distance in millimeters from the top chord of an open web steel joist to its
bottom chord.
Existing – Refers to the existence of something at the time of consideration.
Ground Snow – Refers to the climatic data for a 1 in 30 or 1 in 50 year storm snow load.
Live Load – Refers to the axial force applied to a structural faming system that is variable and in a
constant state of change.
Open Web Steel Joist – Refers to a structural component of a building that generally supports
floors or roof systems.
Proposed – Refers to the suggested consideration or acceptance of an action.
Rain Load – Refers to the climatic data for a 1 in 30 or 1 in 50 year storm rain load.
Serviceability Limit States – Refers to conditions of a structure under which the structure ceases
to fulfill the function for which it was designed and that restrict the intended use and occupancy of
the structure.
Snow Load Accumulation – Refers to the accumulation of snow on roof caused by snowdrifts.
Spacing – Refers to the distance between the centerline of two open web steel joists.
Span – Refers to the length from shoe to shoe of an open web steel joist.
Specified Snow Load – Refers to the snow and associated rain accumulation on a roof or and
other building surface.
Steel Deck – Refers to structural floor or roof element spanning between adjacent joists.
Superimposed – Refers to a load that is in addition to the existing dead load of a structure.
Total Factored Load – Refers to the product of a specified load and its load factor.
Tributary Width – Refers to the width that a structural member must support. For uniformly
distributed system, the tributary width is equal to the spacing of the structural member.
Ultimate Limit States – Refers to conditions that concern the safety of a structure under which
the structure ceases to fulfill the function for which it was designed.


23

APPENDIX ‘A’
SPECIFIED SNOW LOAD S1
The specified snow load (or live load) is calculated using the following formula,
where,
We are assuming a large commercial or industrial building of 140,000 square feet (or
13,832m2
) with the dimensions of 91m by 152m.
Therefore,
Is = 1.0
Ss = 1.8kN/m2
(as tabulated in Appendix C of the 1995 NBCC)
Cb= 1.0 – (30/Lc)2
Lc = (2W) – (W2
/ L)
Where,
W = the width of the building in meters.
L = the length of the building in meters,
Therefore,
Lc = (2 x 91m) – (91m2
/ 152m)


24

Lc = 128 > 70
Therefore,
Cb= 1.0 – (30/128)2
Cb= 0.95
Cw= 1.0
Cs= 1.0
Ca= 1.0
Sr= 0.4kN/m2
(as tabulated in Appendix C of the 1995 NBCC)
Therefore,
S = 1.0 [1.8kN/m2
(0.95 x 1.0 x 1.0 x 1.0) + 0.4kN/m2
]
S = 2.1kN/m2


25

APPENDIX ‘B’
SPECIFIED SNOW LOAD S2
The specified snow load (or live load) is calculated using the following formula,
where,
We are assuming a large commercial or industrial building of 140,000 square feet (or
13,832m2
) with the dimensions of 91m by 152m.
Therefore,
Is = 1.0
Ss = 2.0kN/m2
(as tabulated the 2010 NBCC)
Cb= 1.0 – (30/Lc)2
Lc = (2W) – (W2
/ L)
Where,
W = the width of the building in meters.
L = the length of the building in meters,
Therefore,
Lc = (2 x 91m) – (91m2
/ 152m)


26

Lc = 128 > 70
Therefore,
Cb= 1.0 – (30/128)2
Cb= 0.95
Cw= 1.0
Cs= 1.0
Ca= 1.0
Sr= 0.4kN/m2
(as tabulated in the 2010 NBCC)
Therefore,
S = 1.0 [2.0kN/m2
(0.95 x 1.0 x 1.0 x 1.0) + 0.4kN/m2
]
S = 2.3kN/m2

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