More • Graphic: Roofs, wind and hurricane straps explained • Code Minimum: A Globe series • Reader callout: Share your extreme-weather stories
Inside a black, hangar-sized dome, the roar of 106 massive fans, some as wide as monster-truck tires, is deafening. White smoke is blown in pillars out of two flues, spun faster and faster by the fans into a familiar, menacing shape – a tornado.
This is the world’s largest twister simulator.
Located in the rural outskirts of London, Ont., The Wind Engineering, Energy and Environment dome, or WindEEE for short, is a research facility of Western University. The work being done here advances our understanding of complex wind systems and is important because Canada ranks second globally, behind the U.S., for the most tornadoes recorded per year.
Destructive twisters usually strike southern Ontario, southern Quebec, and the southern Prairies – and it’s a problem that’s getting worse. As the Earth warms, tornadoes, as well as other extreme weather events, are increasing in frequency and severity in Canada and around the world. These natural disasters can be deadly and can cost millions, if not billions, in insured property damage.
WindEEE is used to assess how buildings and other infrastructure will perform under extreme wind conditions, supporting the work of scientists with the university’s Northern Tornadoes Project. Since the dome opened in 2011, engineers have looked at the impact of high winds and tornadoes on transmission lines and low-rise buildings, as well as roof-to-foundation connections in light-frame wood houses and the performance of structural sheathing panels that cover a building’s frame.
Tornado events investigated by Northern Tornadoes Project in Ontario, by Enhanced Fujita scale rating, 2017–2022
Data as of Jan. 18, 2023
ONTARIO
Thunder Bay
Ottawa
Enhanced Fujita rating
EF0: 105–137 km/h
EF1: 138–177 km/h
Toronto
EF2: 178–217 km/h
EF3: 218–266 km/h
BREAKDOWN BY YEAR
80
67
70
66
60
51
50
40
32
30
17
20
10
6
0
2017
2018
2019
2020
2021
2022
MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: NORTHERN TORNADOES PROJECT, WESTERN UNIVERSITY
Tornado events investigated by Northern Tornadoes Project in Ontario, by Enhanced Fujita scale rating, 2017–2022
Data as of Jan. 18, 2023
ONTARIO
Thunder Bay
Ottawa
Enhanced Fujita rating
EF0: 105–137 km/h
Peterborough
Sarnia
EF1: 138–177 km/h
EF2: 178–217 km/h
Toronto
EF3: 218–266 km/h
BREAKDOWN BY YEAR
80
67
70
66
60
51
50
40
32
30
17
20
10
6
0
2017
2018
2019
2020
2021
2022
MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: NORTHERN TORNADOES PROJECT, WESTERN UNIVERSITY
Tornado events investigated by Northern Tornadoes Project in Ontario, by Enhanced Fujita scale rating, 2017–2022
Data as of Jan. 18, 2023
BREAKDOWN BY YEAR
80
67
70
66
60
ONTARIO
51
50
40
32
30
Thunder Bay
Ottawa
17
20
Enhanced Fujita rating
EF0: 105–137 km/h
10
Peterborough
6
Sarnia
EF1: 138–177 km/h
EF2: 178–217 km/h
0
Toronto
EF3: 218–266 km/h
2017
2018
2019
2020
2021
2022
MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: NORTHERN TORNADOES PROJECT, WESTERN UNIVERSITY
A home struck by a tornado in Barrie, Ont., lies in ruins in July of 2021.Northern Tornadoes Project, Western University
Gregory Kopp of Western University studied the aftermath of the Barrie storm.Melissa Tait/The Globe and Mail
The researchers also head out into the field, visiting tornado-stricken places to make observations and survey the damage. Prof. Gregory Kopp was among those who travelled to Barrie, Ont., in the wake of the 2021 tornado that caused an estimated $100-million in insured damages across dozens of homes.
Prof. Kopp and his team counted at least 22 houses that lost their roofs. “When it comes to wind storms, the weakest thing in a house is the toe nails,” he said, referring to the three-inch nails that typically attach a roof to the walls. “Homeowners don’t understand their risk.”
Toe nails are required under Canada’s national building code, but there’s a move afoot to use stronger fasteners to better connect roofs to walls, and walls to the foundation.
The national code is a model code only, meaning it has no legal status until it’s adopted in full, or with amendments, by the provinces and territories. A Globe and Mail analysis of building codes across the country found that regulations governing homes and small buildings are inadequate to withstand the uptick in natural disasters fuelled by climate change.
Across Canada, a patchwork of codes are in effect, with some jurisdictions working off of decades-old national code editions. There are deficiencies in the climate data that dictate how a structure should be built. And, even in its most recent iteration, the national code doesn’t contain any provisions related to wildfires, permafrost loss, flooding or overheating.
WindEEE director Girma Bitsuamlak explains the sensor arrays and models used in this experiment.Melissa Tait/The Globe and Mail
To address what they describe as gaps in the Ontario building code related to increasing wind impact, Prof. Kopp and others – including the City of Barrie, the Canadian Wood Council and the insurance-industry-backed Institute for Catastrophic Loss Reduction (ICRL) – are pushing for the use of hurricane straps or stronger types of screws.
The group submitted a code-change request to the Ontario Ministry of Housing and Municipal Affairs last year proposing the inclusion of stronger fasteners, among other measures, in the section of the provincial code dealing with homes and small buildings.
Hurricane straps, also known as tornado clips, are metal brackets that can fit in the palm of a hand. They’re typically about six-inches long and fasten the roof to the walls.
They’re more expensive than toe nails, but are still relatively cheap, costing only a few hundred dollars per home to purchase and install.
Other measures in the proposal include requiring structural sheathing on all exterior walls in order to increase building stability, and specifying the placement and resistance requirements for anchor bolts, which are used to connect structural elements to concrete. Taken together, the recommendations tie the whole house down, from the roof through to the foundation.
The ICLR estimates that all of the measures in the wind-impact proposal would collectively cost about $1.40 per square foot, or $3,500 for a 2,500-square-foot house. The institute believes the code-change request would reduce the severity of damages by 90 per cent, producing a long-term average benefit of $14,000.
Prof. Kopp holds a hurricane strap as he explains their importance in securing roofs.Melissa Tait/The Globe and Mail
No provincial or territorial building code currently requires hurricane straps. South of the border, the hurricane-prone state of Florida has, since 2002, mandated that new homes have those metal clips. It’s easiest to install them in a new build, though it’s possible to retrofit existing homes via the attic.
“When we looked at structures built in the more modern era after being impacted by the winds of Hurricane Ian, they looked great,” said Dr. Anne Cope, chief engineer with the South Carolina-based Insurance Institute for Business & Home Safety, referring to the category-four hurricane that made landfall last September. “Modern building codes work.”
Hurricane straps, she said, should be used beyond the U.S. coastline because they’re also effective in keeping roofs secure during other types of destructive wind events. And it’s not just about preventing damage to the roof for the sake of the roof alone: An airborne roof could cause injuries or other property damage, and a building’s walls are more likely to collapse when the roof is gone.
But some in the construction industry say the building code isn’t the best tool to improve the durability of homes and other small residential structures. A key argument is that extreme weather events, although more frequent and intense, are still outliers. Constructing to a higher standard, then, is viewed by some to be unnecessary, overly complex and unduly costly.
There’s also the matter of the sometimes-competing goals of climate mitigation and adaptation. For example, when it comes to wind-impact and stability, wood sheathing on the exterior of a home is better than insulated foam sheathing. But insulated foam sheathing is better for energy efficiency. The best approach, then, would be to attach the insulated foam sheathing on top of the wood sheathing.
“You can have it both ways, if cost isn’t an object,” said Mike Memme, operations manager with Mountainview Building Group and a vice-president of the Ontario Home Builders’ Association. He said the association hasn’t yet adopted a position on the Ontario wind-impact proposal, but is supportive of science-based, affordable resilience measures. Speaking in his capacity as a builder, Mr. Memme said it’s inevitable that resilience measures will eventually make their way into the code. “From our perspective,” he said, “we want to go step by step and do it properly.”
Barrie on July 15, 2021, shows several homes with their roofs sheared off by the tornado.Northern Tornadoes Project, Western University
This Barrie house, belonging to Jon Hunwicks, now has hurricane straps. In 2021, the roof came off completely.Melissa Tait/The Globe and Mail
Due to the time it takes to ensure code changes are necessary, effective at addressing the issue at hand, and not overly burdensome, the code-change process tends to be slow and cumbersome. Proposals can take years to weave through the national, provincial or territorial systems.
In a May 18, 2022, letter to a director within the Ontario Ministry of Municipal Affairs and Housing, Barrie’s chief building official at the time outlined the case for changing the way homes are constructed. Michael Janotta, who recently retired from his role with the city, wrote that the damage wrought by the 2021 tornado provided an opportunity to see the weaknesses in how houses are currently built.
“It is quite likely that most of the structural damage, which occurred because of the EF2 tornado, can be significantly reduced or eliminated,” he wrote, referring to the Enhanced Fujita scale, which ranks tornadoes from zero to five based on wind speed. “Paying attention to specific construction details would significantly reduce repair costs, disruption to life and potential loss of life for affected homeowners.”
The proposal has gone out for public consultation and is under consideration for the next edition of the provincial code, slated to be in effect in 2024. A spokesperson for the ministry said in an e-mail that the province has also shared the proposal with the National Research Council (NRC), the federal agency involved in the national code-making process, for consideration to be added to the national code.
As far back as 2013, the ICLR submitted a proposal to national code-makers regarding wind. The code-change request stated that toe nails aren’t enough to hold down roofs under high wind loads and there is a need for “connectors that will resist” – in other words, hurricane straps.
The Standing Committee on Housing and Small Buildings, which reported to the independent Canadian Commission on Fire and Building Codes, rejected the ICLR’s proposal in 2014. The committee, which was comprised of regulatory, industry and expert stakeholders, was not convinced that tornadoes were a threat. “In the absence of examples of failures in the field, the [working group] does not see the need to investigate this further,” the summary of the decision says.
Prof. Kopp has long sought building-code measures that would allow for better storm-proofing measures such as hurricane straps.Melissa Tait/The Globe and Mail
Prof. Kopp said he and others have been pushing for hurricane straps and other wind-impact measures for years. He thinks the 2021 Barrie tornado may be the event that tips the scales toward greater resiliency measures in the code. “It’s starting to change the narrative,” he said.
The provinces and territories have committed to harmonizing their codes with the national code to reduce trade barriers across jurisdictions. If national code-makers decide to require hurricane straps, it’s likely that the fasteners will eventually make it into codes across the country.
Frank Lohmann, the director of building science with the Canadian Home Builders’ Association, noted that the Canadian Standards Association (CSA) last year published a new wind-impact standard for low-rise, wood-framed houses.
The standard contains design and construction guidance to withstand EF2 tornado-level wind speeds. It’s voluntary and hasn’t been incorporated into the national code or any provincial or territorial regulations. The design target of EF2 tornadoes was chosen because it’s estimated that over 90 per cent of tornadoes in Canada fall in that range. The standard contains provisions related to fasteners, sheathing and the anchorage of buildings to the foundation.
Mr. Lohmann said he would like to see the CSA guidance applied in the field, for both new builds and major renovations, as he has questions around the cost of implementing the standard and the capacity of local officials to inspect buildings for compliance.
He encourages builders to go ahead and install better protections if they are able and wish to do so. “Should places voluntarily try it out? Yes,” he said. “Nothing is preventing people from doing certain things right now.”
Reader callout: Share your stories of extreme weather at home
Has your home been affected by extreme weather in Canada? The Globe wants to hear from you. Share your story in the box below or e-mail audience@globeandmail.com.
Graphic: Roof design, wind and hurricane straps explained
1
2
4
5
3
1
HIP ROOFS
A hip roof, which is sloped on all sides, is more resistant to wind damage than a gable-style roof.
Wind
GABLE-ENDED ROOFS
Gable roofs present large obstacles to the full force of the wind and are subjected to high uplift forces.
Gable roofs can be reinforced with bracing which often consist of two-by-fours placed in an ‘X’ pattern at both ends of the attic.
Side-view
2
BUILDING CONSTRUCTION
A
B
C
D
A
HURRICANE STRAPS
Regardless of roof type, these galvanized steel straps help keep the roof fastened to the walls.
B
STRUCTURAL SHEATHING
Installing them on exterior walls can increase building stability.
C
IMPACT-RESISTANT GLASS
Using it can prevent wind-blown debris from breaking windows and entering the building.
D
ANCHOR BOLTS
They are used to connect structural elements to concrete.
3
ANCHORING OUTBUILDINGS
Anchoring storage sheds and other outbuildlings helps prevent them from becoming flying debris.
4
TREES AROUND THE PROPERTY
The distance between the building and any tree should be greater than the height of the tree when it reaches full growth.
5
IMPACT-RESISTANT GLASS
Using it can prevent wind-blown debris from breaking windows and entering the building.
MURAT YÜKSELIR / THE GLOBE AND MAIL,
SOURCE: FEMA; AMERICAN EARTH ANCHORS
1
2
4
5
3
1
HIP ROOFS
A hip roof, which is sloped on all sides, is more resistant to wind damage than a gable-style roof.
Wind
GABLE-ENDED ROOFS
Gable roofs present large obstacles to the full force of the wind and are subjected to high uplift forces.
Gable roofs can be reinforced with bracing, which often consists of two-by-fours placed in an ‘X’ pattern at both ends of the attic.
Side-view
2
BUILDING CONSTRUCTION
A
B
C
D
A
HURRICANE STRAPS
Regardless of roof type, these galvanized steel straps help keep the roof fastened to the walls.
B
STRUCTURAL SHEATHING
Installing them on exterior walls can increase building stability.
C
IMPACT-RESISTANT GLASS
Using it can prevent wind-blown debris from breaking windows and entering the building.
D
ANCHOR BOLTS
They are used to connect structural elements to concrete.
3
ANCHORING OUTBUILDINGS
Anchoring storage sheds and other outbuildlings helps prevent them from becoming flying debris.
4
TREES AROUND THE PROPERTY
The distance between the building and any tree should br greater than the height of the tree when it reaches full growth.
5
IMPACT-RESISTANT GLASS
Using it can prevent wind-blown debris from breaking windows and entering the building.
MURAT YÜKSELIR / THE GLOBE AND MAIL,
SOURCE: FEMA; AMERICAN EARTH ANCHORS
GABLE-ENDED ROOFS
HIP ROOFS
Wind
Side-view
A hip roof, which is sloped on all sides, is more resistant to wind damage than a gable-style roof.
Gable roofs present large obstacles to the full force of the wind and are subjected to high uplift forces.
Gable roofs can be reinforced with bracing, which often consists of two-by-fours placed in an ‘X’
pattern at both ends of the attic.
TREES AROUND THE PROPERTY
The distance between the building and any tree should be greater than the height of the tree when it reaches full growth.
A
HURRICANE STRAPS
Regardless of roof type, these galvanized steel straps help keep the roof fastened to the walls.
A
STRUCTURAL SHEATHING
B
Installing them on exterior walls can increase building stability.
B
C
C
IMPACT-RESISTANT GLASS
Using it can prevent wind-blown debris from breaking windows and entering the building.
ANCHORING
OUTBUILDINGS
Anchoring storage sheds and other outbuildlings helps prevent them from becoming flying debris.
ANCHOR BOLTS
D
They are used to connect structural elements to concrete.
D
MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: FEMA; AMERICAN EARTH ANCHORS
GABLE-ENDED ROOFS
HIP ROOFS
Wind
Side-view
A hip roof, which is sloped on all sides, is more resistant to wind damage than a gable-style roof.
Gable roofs present large obstacles to the full force of the wind and are subjected to high uplift forces.
Gable roofs can be reinforced with bracing, which often consists of two-by-fours placed in an ‘X’
pattern at both ends of the attic.
TREES AROUND THE PROPERTY
The distance between the building and any tree should be greater than the height of the tree when it reaches full growth.
A
HURRICANE STRAPS
Regardless of roof type, these galvanized steel straps help keep the roof fastened to the walls.
A
STRUCTURAL SHEATHING
B
Installing them on exterior walls can increase building stability.
B
C
C
IMPACT-RESISTANT GLASS
Using it can prevent wind-blown debris from breaking windows and entering the building.
ANCHORING
OUTBUILDINGS
Anchoring storage sheds and other outbuildlings helps prevent them from becoming flying debris.
ANCHOR BOLTS
D
They are used to connect structural elements to concrete.
D
MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: FEMA; AMERICAN EARTH ANCHORS
GABLE-ENDED ROOFS
HIP ROOFS
Wind
Side-view
A hip roof, which is sloped on all sides, is more resistant to wind damage than a gable-style roof.
Gable roofs present large obstacles to the full force of the wind and are subjected to high uplift forces.
Gable roofs can be reinforced with bracing, which often consists of two-by-fours placed in an ‘X’ pattern at both ends of the attic.
TREES AROUND THE PROPERTY
The distance between the building and any tree should be greater than the height of the tree when it reaches full growth.
A
HURRICANE STRAPS
Regardless of roof type, these galvanized steel straps help keep the roof fastened to the walls.
A
STRUCTURAL SHEATHING
B
Installing them on exterior walls can increase building stability.
B
C
IMPACT-RESISTANT GLASS
Using it can prevent wind-blown debris from breaking windows and entering the building.
C
ANCHOR BOLTS
D
They are used to connect structural elements to concrete.
ANCHORING
OUTBUILDINGS
MURAT YÜKSELIR /
THE GLOBE AND MAIL,
SOURCE: FEMA; AMERICAN
EARTH ANCHORS
Anchoring storage sheds and other outbuildlings helps prevent them from becoming flying debris.
D
Extreme weather: More from The Globe and Mail
The Decibel podcast
Storms are changing across Canada, but not in the ways you might expect. The Decibel learns more from David Sills, executive director of the Northern Tornadoes Project at Western University. Subscribe for more episodes.
In depth
Canada’s disaster aid system is overwhelmed, leaving victims to rebuild on their own
In Canada’s biggest cities, vulnerability to rising temperatures may depend on your neighbourhood